Background

F1000Research

2046-1402

F1000 Research Limited

London, UK

10.12688/f1000research.154866.1

Research Article

Articles

Chest Wall Hydatid Disease: Surgical management and risk Factors for Recurrence and Mortality

[version 1; peer review: 1 approved, 1 not approved]

Saad

Asma

Conceptualization Data Curation Methodology Resources Validation Writing – Original Draft Preparation Writing – Review & Editing https://orcid.org/0000-0001-8812-4902 a 1 2 Bouassida

Imen

Data Curation Methodology Resources Validation Writing – Original Draft Preparation Writing – Review & Editing 1 2 3 Rouis

Houda

Data Curation Methodology Validation Writing – Original Draft Preparation Writing – Review & Editing https://orcid.org/0000-0002-4392-089X b 1 4 Bellali

Hedia

Data Curation Formal Analysis Methodology Supervision Validation https://orcid.org/0000-0003-0375-3844 3 5 Abdelkbir

Amina

Data Curation Resources Writing – Original Draft Preparation 1 2 Abdennadher

Mahdi

Data Curation Resources Writing – Original Draft Preparation 1 2 Houcine

Yoldez

Data Curation Resources Writing – Original Draft Preparation https://orcid.org/0000-0002-7155-5519 1 6 Kwas

Hamida

Data Curation Writing – Original Draft Preparation https://orcid.org/0000-0002-6322-6061 7 Makhlouf

Hassen

Data Curation Resources Writing – Original Draft Preparation 1 8 Mestiri

Mondher

Supervision Validation Visualization Writing – Review & Editing 1 8 Kooli

Mondher

Supervision Validation Visualization Writing – Review & Editing 1 9 Bouali

Sofiene

Data Curation Resources Writing – Original Draft Preparation 1 10 Kallel

Jalel

Data Curation Validation Visualization Writing – Review & Editing 1 10 Zribi

Hazem

Supervision Validation Writing – Review & Editing 1 2 Marghli

Adel

Supervision Validation Writing – Review & Editing https://orcid.org/0000-0002-9200-1478 1 2 1Faculty of Medicine of Tunis, University-Tunis-El-Manar, Tunus, Tunisia 2Department of Thoracic Surgery, Abderrahmen Mami Hospital, Ariana, Ariana, Tunisia 3Research Laboratory "Analysis of the health effects of climate and environmental changes" «LR20SP01», Department of Epidemiology, Abderrahmen Mami Hospital, Ariana, Ariana, Tunisia 4Pulmonary Department 3, Abderrahmen Mami Hospital, Ariana, Ariana, Tunisia 5Preventive and Community Medicine Department, Habib Thameur Hospital, Tunis, Tunisia 6Department of Pathology, Salah Azaiez Institute, Tunis, Tunisia 7Pulmonary Department, Regional Hospital of Gabes Mohammed Ben Sassi, Gabes, Tunisia 8Orthopedics Department, Mohamed-Kassab Institute of Orthopedics, Ksar Said, Tunisia 9Orthopedics Department, Charles Nicolle Hospital, Tunis, Tunisia 10Neurosurgery Department, National Institute of Neurology “Mongi Ben Hmida”, Tunis, Tunisia

a asmasaad20@yahoo.com b hrouis@yahoo.fr

No competing interests were disclosed.

29 10 2024

2024

1297

15 10 2024

2024

This is an open access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Background

Hydatidosis of the thoracic wall differs from other hydatid localizations in its pathophysiology, diagnostic, and therapeutic management. It is a little-studied entity.

The objectives of our work were to describe its surgical management and to analyze the factors that may influence recurrence and mortality.

Methods

A retrospective, descriptive, longitudinal, and multicenter study on four university hospital surgical centers of Tunis, from January 1995 to December 2022 including operated hydatid cysts of the thoracic wall. Overall survival (OS) and cumulative recurrence rates were calculated. Univariate and multivariable Cox regression analyses were performed to identify recurrence and mortality risk factors.

Results

Forty-nine patients were included. The mean age was 41 ± 17 years [8-76]. The main presenting sign was thoracic parietal swelling (n=22). Chest ultrasound and CT scan showed multivesicular formation in 17 and 33 cases, respectively. Muscle involvement was in the intercostal (n=4), paravertebral (n=13), and pectoralis major (n=3) muscles. Bone involvement was vertebral (n=11), costal (n=12), costo-vertebral (n=21) and sternal (n=2). A posterolateral thoracotomy was performed (n=20). Surgical excision at various levels of the chest wall with spinal stabilization (n=15) was performed. Sixty-three percent of the patients received antiparasitic medical treatment. Recurrence occurred in 37% of cases. Four patients died from hydatidosis-related complications. Factors could be independently associated with recurrence such as male gender, and vertebral involvement. The presence of a visceral hydatid cyst located at a distance from the parietal lesion at the time of diagnosis and the occurrence of postoperative infectious complications could increase mortality.

Conclusions

Chest wall hydatidosis represents a rare medical condition where surgery remains the preferred treatment modality. However, it carries a substantial burden of morbidity and mortality, influenced by various factors. Further large-scale studies are necessary to gain a deeper understanding of these factors and to optimize management strategies accordingly.

E granulosus Rib Dorsal vertebra Thoracic Surgery Recurrence Mortality

The author(s) declared that no grants were involved in supporting this work.

Introduction

Hydatidosis or echinococcosis, also known as hydatid cyst or hydatid disease, is a cosmopolitan infectious prevalent in the Mediterranean basin, Australia, and South America. It is caused in humans, an accidental intermediate host, by the presence and development of the hydatid of a cestode of the genus “echinococcus granulosus” that resides in the small intestine of canids. ^{1,
2} Hydatid cysts represent a public health problem in endemic countries, particularly Tunisia, where the incidence is approximately 15.1 per 100,000 inhabitants, ³ as well as in other countries where traditional livestock farming is still practiced, due to its frequency, severity, and socio-economic impact.

The location in the chest wall presents diagnostic, therapeutic, and prognostic problems. The long symptomatic silence of this disease (5-15 years) allows the lesions to spread rapidly before they are discovered, ⁴ thus posing a differential diagnosis problem, explaining the diagnostic delay. Bone lesions are extensive with a very progressive evolution and can lead to definitive neurological complications.

Our study aimed to describe chest wall surgical management and outcomes and identify possible associated recurrence and mortality risk factors.

Methods Ethical consideration

Ethics approval

Ethical approval was waived by the local Ethics Committee of Abderrahmane Mami University Hospital under the number 20/2024 in October 2024.

Patient privacy and informed consent for publication

Written informed consent was obtained directly from the patients by the authors, regardless of their department of origin. Patients consistently provided consent before surgery as per standard hospital practice. Additionally, retrospective consent for study participation was acquired through telephone contact.

Anonymity was respected during data treatment.

Consent for publication of identifiable data

No consent for publication was required as the data had been anonymized. We confirm that such alterations have not distorted the scientific meaning.

Following the Safe Harbor methods outlined by HIPAA, all radiologic images and patient photographs used in the study were thoroughly de-identified to ensure patient privacy. This process involved removing any direct identifiers such as patient names, dates of birth, medical record numbers, and facial features that could potentially lead to the re-identification of the individuals. Additionally, any metadata embedded within the images, such as timestamps or institution-specific details, were removed. This de-identification procedure was carefully followed to comply with the HIPAA guidelines and protect patient confidentiality throughout the study.

Population source

The present study was retrospective, descriptive, and multicentric. It was over twenty-eight years: from January 1995 to December 2022.

Our study was carried out in four university hospital centers in Tunis: the thoracic surgery department of Abderrahman Mami Hospital, Ariana, the neurosurgery department of the National Institute of Neurology in Tunis, the orthopedics department of the Mohamed-Kassab Institute of Orthopedics and the orthopedics department of Charles Nicolle Hospital in Tunis. We used the admissions database of these university hospital centers to collect records of patients operated on for hydatidosis of the chest wall (defined as hydatidosis affecting the bone (ribs, vertebrae, and sternum) and soft tissues). Fifty records were retrieved.

Inclusion criteria

We included all operated patients for hydatidosis of the chest wall, with complete records (observation, radiological findings, operative report, anatomopathological report, follow-up).

Non-inclusion criteria

We did not include the patients operated on for suspected chest wall hydatidosis (CWH) and whose diagnosis was not retained after surgery or pathological examination, patients with confirmed CWH but who were not operated on (refusal, inoperable patients with high anesthetic risks).

We applied the inclusion and non-inclusion criteria and eliminated incomplete and unusable records. We retained forty-nine patients operated on for chest wall hydatidosis.

Data collection

A data collection form was drawn up in a standardized manner to collect all elements necessary to meet the objectives of our study.

Preoperative data

For each patient, we collected information about epidemiological and anamnestic data: age, gender, geographical origin (rural or urban), the department of origin (thoracic surgery, orthopedics, or neurosurgery), notion of hydatid contagion, family history of hydatid cyst (HC), personal history of visceral hydatid cyst. We consider a history of multiple visceral hydatidosis and hydatid involvement of more than three viscera. We also examined clinical parameters such as the time to consultation (the time from the onset of symptomatology to the date of consultation), time to treatment (the time between the onset of the symptomatology and the date of surgery), the circumstances of discovery, including incidental findings, chest pain, swelling of the soft tissues of the thoracic wall presenting as a parietal tumefaction of the posterior thoracic or paravertebral wall, neurological symptoms, and respiratory involvement. Additionally, we evaluated physical examination parameters such as general examination, thoracic floor assessment, and neurological and abdominal examinations.

The radiological assessment included a chest X-ray, X-ray of the spine, coastal grid, thoracic, soft tissue, and abdominal ultrasound, CT-scan, Magnetic Resonance Imaging (MRI), and other radiological examinations such as medullary arteriography. Biological tests were carried out, including hydatid serology and a blood count to check for hypereosinophilia.

Operative data

We specified the therapeutic management elements: anesthesia, surgical position, surgical approach, per-operative findings, and surgical procedure: which we have divided into three stages: surgical resection of part of the chest wall (including ribs, vertebrae, and/or muscles), surgical spinal stabilization: anterior by a bone marrow transplant or by osteosynthesis with a fixation material and conservative surgical procedure when the operation is performed only on the cystic lesion without ablating a part of the thoracic wall. We identified the used scolicidal solution (hydrogen peroxide, povidone-iodine, hypertonic saline), the protection of the operating field (use of soaked gauze in scolicidal solution to protect pleura and soft tissues for possible scolex dissemination), and we mentioned per-operative complications.

Postoperative data

We recorded the duration of drainage, hospital stay, immediate postoperative course: simple or complicated, and late complications. Late course: was assessed by clinical examination (neurological by ASIA score to evaluate motor skills and sensitivity) and postoperative sequelae. During the follow-up period, every hydatid recurrence was recorded (time, treatment modalities, surgical treatment (approach, procedure, number of repeat surgeries, evolution after treatment of recurrences). Antiparasitic medical treatment was noted (molecule and length of treatment) and the pathological examination. We identified the mortality (frequency, causes, delay). We defined lost to follow-up patients as those who missed outpatient visits for over three consecutive years.

Statistical analysis

The data was analyzed using the IBM Statistical Package for the Social Sciences 25.0 software, accessed through the free 30-day trial available on IBM’s official website ( https://www.ibm.com/products/spss-statistics#110). In our study, we proceeded to Calculate absolute and relative frequencies for categorical variables, means, medians (with minimum and maximum), and standard deviations for quantitative variables. For the quantitative variables, the distribution of the population was tested for normality. If the distribution was normal, the variables were described as mean, otherwise as median. We used the Kaplan-Meier survival curve by calculating the cumulative survival to study the survival relationships of the elected variables associated with recurrence and the elected variables associated with mortality. For the multivariate study, we used Cox regression to determine factors independently associated with recurrence and factors independently associated with mortality. All tests were two-sided, and a two-tailed probability value of 0.05 or less was considered statistically significant.

Results

During the study period, 49 patients were operated on for CWH. The mean age of our population was 41 ± 17 years [8-76 years] with a male predominance.

At the time of diagnosis, 15 patients had associated hydatid involvement at a distance, the others had exclusive parietal involvement. Bone involvement was vertebral (n=11), only costal (n=12), costovertebral (n=21) and sternal (n=2). There was soft tissue involvement adjacent to the costovertebral involvement in the intercostal and paraspinal muscles (n=13), as well as in the soft tissue of the supraclavicular fossa (n=2) with exclusive primary involvement of the pectoralis major muscle (n=1) and the paraspinal muscle (n=1).

The diagnosis of CWH was an incidental finding in three cases. The other patients were symptomatic with a combination of functional signs: thoracic pain (n=23), parietal swelling (n=22) ( Figure 1A), neurological signs (n=22), and respiratory signs (n=7) ( Table 1).

Figure 1. Costal hydatidosis.

A parietal swelling (arrowhead); B Chest radiograph, circle arrowed the cyst and its effect on ribs; C echography showing hydatid vesicles (arrowhead); D CT image: cystic lesion with cortical costal lysis (arrowhead).

Table 1. Patient characteristics.

Characteristics		Number (%)
Epidemiological Characteristics
Age in years:median (minimum-maximum)		41 [8-76]
Sex	Male	31 (63.2)
Sex	Female	18 (36.7)
Rural origin		42 (85.7)
Clinical Characteristics
Exclusive parietal involvement		34 (69.3)
Remotely associated hydatid cyst	hepatic HC	7 (14.2)
	pulmonary HC	5 (10.2)
	secondary pleural hydatidosis	2 (4)
	renal HC	1 (2)
	psoas muscle	1(2)
	Clinical revealing signs
	incidental	3 (6.1)
	parietal swelling	22 (44.8)
	Thoracic pain	23 (46.9)
	gait disturbance	6 (12.2)
	mainly back pain	4(8.1)
	paresthesia	2 (4)
	heaviness of the body	3 (6.1)
	Physical exam signs
	Parietal swelling	22 (44.8)
	pain on palpation of the ribs	10 (20.4)
	spinal deformity	6 (12.24)
	pain on palpation of the spinous processes	14 (28.57)
	paraparesis	2 (4)
	paraplegia	3 (6.1)
	pyramidal syndrome	6 (12.2)
	Hypoesthesia (lower limbs)	6 (12.2)
Radiological characteristics
CT scan radiological aspects	multivesicular polylobate formation	33 (67.3)
	costal lysis	35 (71.4)
	Vertebral lysis	23 (46.9)
	Sternal lysis	2 (4)
Vertebromedullary MRI	Multiloculated cystic mass	24 (48.9)
Vertebromedullary MRI	Intracanal extension	20 (40.8)

Paraclinical investigations were carried out: chest X-ray was performed in 48 patients, i.e., 98% of cases, and mainly showed a parietal opacity in 19 cases ( Figure 1B).

Ultrasound of the soft tissues was performed in 18 cases and the most frequent aspect was a hypoechogenic multivesicular formation (n=13) which guided the diagnosis ( Figure 1C).

Abdominal ultrasound was performed in 44 cases as part of the etiological and extension assessment of the hydatid disease and showed a hepatic HC (GHARBI type IV) in nine cases.

The thoracic CT scan was performed in 94% of cases ( Table 1). Costal damage was in the posterior arch in 25 cases (51%). A tiered involvement of more than two ribs was observed in 43% of the cases, with a predominance of lesions at the Fourth to ninth rib level. The vertebral involvement was in the vertebral body in 21 cases and the intervertebral disc in two cases. In 16% of cases, the number of affected vertebrae was two or more. The most affected levels were D7-D9 (n=11) explained by the richness of the vascularization of this spine segment ( Figure 1D, Figure 2).

Figure 2. Thoracic CT scan and MRI chest wall hydatidosis features.

A-B Destruction of the spine and intracanal diffusion of hydatidosis (arrowhead and circle); C-D MRI showing a large multivesicular mass depending on the paravertebral muscle (arrowheads).

There was soft tissue involvement adjacent to the spinal involvement. The mean major axis of the lesion was 7.8 cm, with a size ranging from 3 to 30 cm in the major axis. Twenty-three patients had a lesion with a large diameter ranging from 5 to 10 cm.

Vertebro-medullary magnetic resonance imaging (MRI) was performed in 24 patients, i.e., 49% of cases ( Table 1).

All patients were operated on. For costovertebral involvement, posterolateral thoracotomy was performed in 11 cases (61% of cases), a posterior approach in four cases (22% of cases), and a combined approach in 3 cases (17% of cases) ( Figure 3).

Figure 3. Preoperative views.

A Surgical position, arrow showing paravertebral swelling; B Flattening of hydatid abscesses; C Posterior approach revealing vertebral and intracanal hydatidosis; D Posterior spinal stabilization (osteosynthesis).

The surgical procedure was divided into three modalities: radical surgical removal, spinal stabilization, and conservative surgery without costovertebral resection ( Table 2).

Table 2. Surgical management.

Surgical approach	Number (n)
Posterolateral thoracotomy (PLT)	18
Posterior approach (midline incision)	16
Elective incision: anterior or posterior	11
Combined approach (PLT or elective approach + posterior approach)	3
ROOS route (axillary)	1
Total (N=49)	49
Radical surgical removal

Level		Surgical removal	Number (n)
Bone involvement	Spinal	Partial corporectomy	3
		Hemicorporectomy+ bone grafting	1
		Total corporectomy	1
	Laminectomy only		15
	Costal	Simple rib resection (anterior or posterior arch)	8
	Costal	staged rib resection (≥2 ribs)	5
	Costo-vertebral	costo-transversectomy only	8
	Costo-vertebral	costovertebral resection	3
	Sternal	Manubriectomy	2
Muscle involvement		Partial muscle resection	10
Associated involvement		Wedge resection of lung parenchyma	3
Spinal stabilisation

Surgical stabilization	Number (n)
No	14
Anterior spinal stabilization (by graft)	6
Posterior spinal stabilization (osteosynthesis)	12
Total	32
Conservative surgery without costovertebral resection

Conservative surgery	Number (n)
Flattening hydatid abscesses	15
Cystotomy + draining + cystic wall resection	10
Fistula resection	4
Roughening of the vertebral body ± transverse process	2

A primordial time is the protection of the operating field by a scolicide solution. The main solutions were hypertonic saline and hydrogen peroxide ( Figure 3).

The immediate postoperative course was simple in 94% of cases. The average length of hospitalization was 23.5 [5-55] days for isolated vertebral involvement, 19.8 [4-123] days for costovertebral involvement, 8.3 [1-35] days for isolated rib involvement, and three days for exclusive muscular involvement of hydatid disease. The difference between the average length of stay for the different conditions was not statistically significant (p=0.70).

Medical treatment was prescribed to all our patients even for those who had a complete resection and was taken in 63% of cases. The antiparasitic molecule prescribed was albendazole in the form of a 400 mg tablet, per day in two doses, in the form of 21-day courses separated by one week. The antiparasitic medical treatment was mainly taken postoperatively in 14 cases and after the recurrence in 11 cases. The duration of the antiparasitic medical treatment was more than one year in 17 cases, i.e., 55% of the patients who had received medical treatment.

Post-operative complications occurred in 24% of cases. There are three types of complications: neurological, infectious and decubitus. Neurological complications included paraplegia in two cases and paresis in six cases. The three main postoperative infectious complications were surgical wound infection (n=3) and pneumonia acquired by mechanical ventilation (n=3). Pressure sores were the main decubitus complication (n=4).

The postoperative evolutionary aspects were marked by a total disappearance of the initial symptomatology in 22 cases and a clinical aggravation in three cases. On the other hand, the different types of postoperative sequelae were mainly intercostal neuralgia in seven cases and paraplegia in five cases. Recurrence was a frequent complication that determines the prognosis of this rare disease and occurred in 18 cases (37%). The median time to recurrence was one year with extremes ranging from a month to 13 years. For recurrence, patients had medical and surgical treatment in most cases (n=14). For the different surgical revision procedures for recurrence, the main procedure was spinal decompression by laminectomy with partial corporectomy associated or not with spinal stabilization in eight cases. The mean number of repeat surgeries for recurrence was three times with extremes ranging from one to eleven times. Thus 61% of the patients who had a recurrence were reoperated on more than twice.

Overall survival is estimated at 80% at five years. Seven patients (70% of those who died) had vertebral involvement. Patients with vertebral hydatid involvement had a 5-year survival of 71%.

We conducted an analytical study to determine the factors associated with recurrence and mortality. The univariate study looked at several parameters, epidemiological, radio-clinical, and parameters related to the management methods, represented in Tables 3- 4.

Table 3. Results of univariate analysis of factors associated with recurrence.

Factor		Mean time to recurrence (years)	CI 95%	p
Epidemiological parameters
Age	< 30 years	15.246±3.055	[9.259;21.234]	0.943
Age	≥ 30 years	16.337±2.012	[12.394;20.280]	0.943
Gender	Men	13.216±2.221	[8.862;17.570]	0.019
Gender	Women	21.265±2.190	[16.972;25.557]	0.019
Remotely associated hydatid cyst	Yes	12.528±3.232	[6.193;18.863]	0.199
Remotely associated hydatid cyst	No	17.611±1.944	[13.802;21.421]	0.199
Clinico-radiological parameters
Parietal swelling	Yes	20.043±2.125	[15.877;24.208]	0.055
Parietal swelling	No	12.917±2.410	[8.194;17.640]	0.055
Neurological deficit	Yes	7.172±1.998	[3.256;11.088]	0.030
Neurological deficit	No	18.273±1.841	[14.666;21.881]	0.030
Vertebral compression	Yes	3.997±2.304	[0.000;8.512]	0.002
Vertebral compression	No	17.943±1.746	[14.522;21.365]	0.002
Scalopping of posterior wall	Yes	4.780±2.196	[0.476;9.083]	0.002
Scalopping of posterior wall	No	18.179±1.771	[14.708;21.650]	0.002
Involvement of more than 2 vertebrae	Yes	4.994±1.596	[1.866;8.123]	0.001
Involvement of more than 2 vertebrae	No	18.945±1.785	[15.447;22.443]	0.001
Vertebral lysis	Yes	11.587±2.377	[6.927;16.246]	0.013
Vertebral lysis	No	20.467±2.018	[16.513;24.422]	0.013
Paravertebral extension	Yes	10.251±2.251	[5.838;14.664]	0.001
Paravertebral extension	No	22.266±1.758	[18.821;25.711]	0.001
Intracanal extension	Yes	9.524±2.325	[4.966;14.081]	<10 ^-3
Intracanal extension	No	21.533±1.831	[17.944;25.121]	<10 ^-3
Vertebral involvement	Yes	12.268±2.041	[8.268;16.268]	0.004
Vertebral involvement	No	23.985±1.497	[21.051;26.918]	0.004
Modification of medullary signal	Yes	6.923±6.077	[0.000;18.833]	0.099
Modification of medullary signal	No	16.815±1.743	[13.400;20.231]	0.099
Therapeutic management modalities
Laminectomy only	Yes	5.999±1.752	[2.565;9.434]	0.002
Laminectomy only	No	19.730±1.788	[16.227;23.234]	0.002
Complete Costal resection	Yes	6.537±2.140	[2.342;10.732]	0.026
Complete Costal resection	No	17.836±1.835	[14.240;21.433]	0.026
Anti-parasitic medical treatment	Yes	9.769±1.898	[6.050;13.489]	<10 ^-3
Anti-parasitic medical treatment	No	24.272±1.223	[21.876;26.669]	<10 ^-3
Postoperative neurological complications	Yes	2.426±1.563	[0.000;5.490]	<10 ^-3
Postoperative neurological complications	No	19.246±1.701	[15.911;22.581]	<10 ^-3
Postoperative decubitus complications	Yes	4.915±2.420	[0.172;9.658]	0.003
Postoperative decubitus complications	No	17.825±1.768	[14.359;21.290]	0.003
Neurogical Sequelae	Yes	9.039±2.837	[3.479;14.599]	0.002
Neurogical Sequelae	No	19.382±1.859	[15.739;23.026]	0.002

Table 4. Results of univariate analysis of factors associated with mortality.

Parameter		Mean time to death (Years)	CI 95%	P
Preoperative parameters
Age	<30 years	24.125±0.088	[23.952;24.298]	0.121
Age	≥30 years	19.233±1.667	[15.965;22.501]	0.121
Chest pain	Yes	18.071±1.987	[14.178;21.966]	0.023
Chest pain	No	23.765±0.956	[21.891;25.638]	0.023
Remotely associated hydatid cyst	Yes	16.112±2.710	[10.799;21.424]	0.061
Remotely associated hydatid cyst	No	22.412±1.192	[20.076;24.748]	0.061
Exclusive parietal lesion	Yes	23.196±0.882	[21.467;24.925]	0.003
Exclusive parietal lesion	No	14.897±2.684	[9.635;20.158]	0.003
Costo-vertebral involvement	Yes	18.184±2.132	[14.006;22.362]	0.040
Costo-vertebral involvement	No	22.941±1.309	[20.376;25.506]	0.040
Intracanalar extension	Yes	17.913±2.441	[13.128;22.628]	0.075
Intracanalar extension	No	22.371±1.370	[19.687;25.056]	0.075
Operative and postoperative parameters
Complete Rib resection	Yes	16.900±3.785	[9.482;24.318]	0.046
Complete Rib resection	No	21.768±1.313	[19.194;24.342]	0.046
Post-operative infectious complications	Yes	13.667±3.484	[6.837;20.496]	0.001
Post-operative infectious complications	No	22.967±1.136	[20.741;25.193]	0.001
Post-operative decubitus	Yes	15.667±5.484	[4.919;26.415]	0.057
complications	No	21.483±1.303	[18.928;24.038]	0.057

The multi-varied study of these parameters identified the factors independently associated respectively with recurrence and mortality, which are shown in Table 5.

Table 5. Results of multivariate analysis of factors associated with recurrence and mortality.

Factors	P	HR (CI 95%)
Analysis of recurrence
Gender	0.006	6.03 [1.68;21.56]
Vertebral involvement	0.025	10.20 [1.33;77.85]
Anti-parasitic medical treatment	0.006	17.33 [2.25;133.23]
Analysis of mortality
Associated distant hydatid cyst	0.005	31.05 [2.80;343.99]
Post-operative infectious complications	0.002	40.23 [3.91;413.62]

Male gender, vertebral involvement, and antiparasitic medical treatment could be independently associated with recurrence. Associated distant hydatid cysts and postoperative infectious complications were the two factors associated with mortality.

Discussion

CWH is an entity that encompasses the involvement of the soft tissues and the costovertebral and sternal bones.

The literature review revealed only case studies or articles about a few cases in the descriptive framework. Our work has added to the literature the experience of four university hospitals in a country where hydatidosis is endemic, through a descriptive and analytical study attempting to find factors associated with recurrence and factors associated with mortality that could jeopardize functional and vital prognosis.

The curative treatment for thoracic parietal echinococcosis is surgical. ^{5,
6} Results depend on the extent of the lesions, their location, and the presence of complications. It must be the subject of an exhaustive work-up and treated as a “malignant tumor” by a wide resection passing through healthy margins. ⁷

For isolated rib involvement, the main surgical procedure was resection of the anterior or posterior arch or both. This resection was extended to more than two ribs in five cases.

For sternal involvement, the procedure was a manubriectomy. For isolated soft tissue involvement, resection of the hydatid cyst was combined with partial resection of the muscle involved.

For costovertebral lesions, a multidisciplinary surgical team comprising thoracic surgeons and orthopedic surgeons or neurosurgeons is required.

From a technical point of view, the approach to the thoracic parietal lesion is often facilitated and guided by the ossifluent abscess, which is surgically traversed as far as the primary bony lesion, eliminating the hydatid vesicles in the process. Costovertebral lesions can be treated using a posterior approach alone, a posterolateral approach alone, or a combined approach (posterior and posterolateral). Each of these approaches has its advantages and indications, and a combined approach is recommended in most cases, particularly if a laminectomy has already been performed as part of a neurological emergency. ⁸ Access to the vertebral bodies and ribs is difficult, and resection of hydatid material is often incomplete. The posterolateral approach has several advantages: it allows access to all the vertebral bodies of the dorsal spine and extensive excision of the spine, ribs, and muscles, with the possibility of reconstruction or osteosynthesis, and makes it possible to treat an associated pulmonary, pleural or mediastinal location. For costovertebral involvement, the data in the literature showed that most patients were operated on via the posterior approach. ^{9,
10} This was the only approach used in the series by Khazim ⁹ and Bhavin. ¹¹ Although this approach offers the possibility of spinal decompression, excision of the hydatid process remains incomplete, with a high rate of mortality, neurological deficits, and fistulae. Other teams have used the posterior approach in addition to the posterolateral approach to search for one or more hydatid vesicles that have migrated into the spinal canal, far from the initial site of contamination, or for palliative treatment of multi-stage lesions. ¹² The combined posterior approach associated with PLT is recommended in most cases. ^{9,
10,
13}

In our study, posterolateral thoracotomy was performed most frequently. This was performed in 61% of cases of costovertebral involvement.

Thoracic parietal resection must be carried out with multidisciplinary management. At present, it is recommended to carry out as complete an excision as possible using a “carcinological” strategy. ^{13–
15}

Some hydatid lesions of the thoracic wall, spread over more than five vertebrae, are sometimes unresectable ¹⁴ and require a conservative surgical procedure such as flattening of the hydatid abscesses, or spinal curettage, which was performed in two patients in our series, or even surgical abstention. ¹⁴

Medical treatment with albendazole is the only therapeutic alternative for inoperable patients, even though it may not cure or prevent recurrence. Its use as adjuvant therapy to surgery is generally necessary to prevent systemic dissemination during vesicular rupture and to reduce and delay recurrences. We have adopted this approach in our series. However, some teams believe that albendazole does not act on infested bone without a germ membrane. ¹⁶

Recurrence is considered a poor prognostic factor in chest wall hydatid (CWH) disease, particularly when it involves the vertebrae. Operative mortality of up to 14.4% has been reported in recurrences. ¹⁷

For bone involvement, the results of surgery are far from curative and recurrence is the rule. ^{12,
17,
18} In our series, recurrence was noted in 37% of cases. Recurrence surgery is associated with higher morbidity and mortality than initial surgery. However, most of these operations are only palliative. ¹⁹

Surgery may be repeated several times to completely eradicate echinococcosis but cysts involving the spine cannot be safely resected or excised in their entirety in most patients. ^{17,
19}

There are cases of resistance that respond neither to surgery nor to medication. We report a case diagnosed as hydatidosis of the chest wall and treated with radiotherapy (RT) after medical and surgical therapy had failed. Ulger S et al report a case of hydatidosis of the sternum showing the value of RT for E. multilocularis as an alternative treatment ²⁰; however, based on the literature, we conclude that the effect of RT is not well known in this setting.

Hydatid involvement of the thoracic wall, and principally the spinal location, is associated with a non-negligible mortality rate of 3 to 46%. ²¹ The overall mortality rate was 46% in the study by Zlitni, ²² and 17% in that of Ezzaouia. ²³ Death is, in most cases, the consequence of infectious and decubitus complications. ^{15,
23,
24} In our series, ten patients died. Patients with spinal hydatid involvement had an estimated survival of 71% at five years and 29% at 10 years. There was no statistically significant difference in survival between patients with and without vertebral hydatid disease (p=0.78). This can be explained by the small sample size of our series. Seven patients, i.e., 70% of those who died, had costovertebral hydatid lesions, and four died from complications of hydatid disease, mainly from decubitus complications (n=3). The other three patients were elderly, two of whom had associated pulmonary and secondary pleural hydatidosis.

Few studies have examined survival factors, and none have explored risk factors for recurrence and mortality in this rare condition. In our multivariate analysis, we aimed to identify these factors, finding a recurrence rate of 37% and a mortality rate of 20% among our patients.

According to the literature, thoracic parietal hydatidosis is more frequent in men. ^{14,
25} In our study, we also noted a male predominance. There were 31 men and 18 women, with a sex ratio of 1.7. This may be explained by the fact that males are more likely to associate with canids in rural areas. Gender may be a factor in recurrence (P=0.006), with recidivism six times greater for males (HR=6.032).

Bone echinococcosis can affect all bones but preferentially affects the spine. ^{13,
22} This is the most common location; 42% for Dévé ² and 44% for Zlitni. The site is mainly dorsal (56%). ^{13,
22} It is the most serious because of the neurological complications and the difficulties of surgical eradication. Although hydatidosis of the bone is a parasitic disease, its prognosis should be treated as if it were a malignant lesion. In our series, vertebral involvement is a factor associated with recurrence (P=0.025) and HR=10.2. Unlike visceral sites, the rigid structure of bone prevents the formation of adventitia, allowing parasites to spread through microvesicular infiltration of bone tissue. Exogenous vesiculation is characteristic of bone due to its rigidity, and results in the release of daughter vesicles from the mother vesicle, which explains the frequency of recurrences. There is no clear dividing line between healthy and pathological tissue, which is a major difficulty during surgical removal. ²²

In our series, patients who had taken antiparasitic medical treatment reattract the disease earlier than those who had not (p=0.006). This seems to be unwarranted however it can be justified by the common prescription of antihelminthic treatment for extensive hydatid lesions and the absence of a standardized protocol for this treatment. Certain factors influence the efficacy of benzimidazoles. Todorov et al. found that larger vesicle size, the presence of daughter vesicles, and, notably, bone involvement were associated with a poor response to medical treatment. This may be attributed to the small number of patients in our series. ²⁶

We studied several other factors that could be associated with recurrence and that were only significant in the univariate study. These included clinico-radiological factors such as the neurological deficit, vertebral compression, scalloping of the posterior vertebral wall, vertebral lysis, paravertebral extension, intracanal extension, and involvement of more than two vertebrae. Other factors related to management methods, such as the extent of surgical removal: laminectomy alone, complete costal resection, the occurrence of neurological complications and postoperative decubitus complications, and the occurrence of postoperative sequelae.

This may be explained by the heterogeneity of our sample, with a small enough number of patients to be able to generalize.

The mortality rate of patients followed for echinococcosis of the chest wall, essentially the dorsal spine is 3 to 14%. ^{18,
21,
27}

Hydatid involvement of the thoracic wall, and especially bone involvement, is rare, accounting for less than 2% of all hydatid cases, and is associated with a visceral cyst in 12 to 25% of cases. It is primary, ² rarely secondary, and occurs via the hematogenous route. ²¹ In our series, patients with a visceral hydatid site at a distance from the parietal involvement at the time of diagnosis had a mortality rate 31 times higher, with a significant difference (p=0.005). This suggests that we should consider simultaneous treatment of visceral hydatid lesions if feasible.

Infectious complications can cause high mortality. In our series, mortality was 40 times higher with the occurrence of infectious complications.

We studied several other factors that could be associated with mortality, such as the onset of chest pain, exclusive parietal involvement, which is a protective factor, costovertebral involvement, and costal resection. These were significant only in the univariate study. This may be explained by the small number of patients in our series, which makes it difficult to generalize.

To validate these conclusions and identify the factors contributing to recurrence and mortality, a prospective study with a larger sample size may be necessary. However, this is challenging due to the rarity of the disease.

Conclusion

Surgery remains the treatment of choice for chest wall hydatidosis. If diagnosed early and treated promptly, CWH can go into long-term remission. However, detecting this disease in its early stages can be challenging. This pathology is burdened with recurrence and significant morbi mortality associated with several factors. Recurrence could be associated with male gender and vertebral involvement. Associated distant visceral hydatidosis and postoperative infectious complications could increase mortality. Larger-scale studies are needed to enhance our understanding of this rare condition, improve its management, and minimize factors that could negatively impact postoperative outcomes.

Data availability Underlying data

Figshare: Chest Wall Hydatid Disease: Surgical management and risk Factors for Recurrence and Mortality. figshare. Dataset. https://doi.org/10.6084/m9.figshare.26384143.v1. ²⁸

The project contains the following underlying data: •

Base 2024.sav def (SPSS database of patients included in the study)

Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).

Extended data

Figshare: CANNEVAS HYDATIDOSIS OF THE CHEST WALL. https://doi.org/10.6084/m9.figshare.26771605.v1. ²⁹

This project contains the following extended data: •

Cannevas hydatidosis of the chest wall (A data collection summary sheet)

Data are available under the terms of the Creative Commons Attribution 4.0 International license (CC-BY 4.0).

Software availability statement

The data analysis was conducted using Jamovi version 2.3, which is open-access software available at https://www.jamovi.org. This software provides a range of statistical analysis tools equivalent to proprietary alternatives like IBM SPSS. Jamovi is available under the GNU General Public License (GPL) and is freely accessible for download and use.

References 1

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: Chest wall hydatidosis: a single institution experience. Arch. Clin. Infect. Dis. 2016 Aug;11(4):e35134. 10.5812/archcid.35134

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: Spinal hydatid disease. Spinal Cord. 2002 Apr;40(4):153–160. 10.1038/sj.sc.3101214

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: Thoracotomies latérales et postérolatérales. Encycl. Med. Chir. 2009;4:1–9. (Elsevier Masson, Paris), Techniques Chirurgicales - Thorax, 42-205. 10.1016/S1241-8226(09)39126-4

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: Spinal hydatid disease. South. Med. J. 2006 Feb;99(2):114. 10.1097/01.smj.0000198264.01011.d1

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: Localisation costo-vertébrale compliquée d’une échinococcose multifocale. Intérêt de la chirurgie par voie antérieure. Rev. Mal. Respir. Sep 2005;22(4):673–676. 16294185

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: Spinal hydatid disease: a case series. J. Spinal Cord Med. 2005 Mar;28(5):426–431. 16869090

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: Spinal hydatid disease. Spinal Cord. 1998 Mar;36(3):166–170. 10.1038/sj.sc.3100512

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: Hydatidose vertébrale: approche diagnostique et thérapeutique. Bull. Acad. Natl Med. Feb 2012;196(2):485–495. 10.1016/S0001-4079(19)31840-0

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: Hydatidose thoracique. EMC - Radiologie et imagerie médicale - Cardiovasculaire - Thoracique - Cervicale. janv 2007;2(1):1–17. 10.1016/S1879-8535(07)72754-X

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: Vertebral hydatidosis and paraplegia. J. Bone Joint Surg. Br. 1990 Jan;72-B(1):84–88. 10.1302/0301-620X.72B1.2298801

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: Prise en charge de l’echinococcose vertébrale [Thèse]. Médecine: Tunis. 2019;148.

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: Hydatidose vertebrale (à propos de 22 cas). Rev Maroc Chir Orthop Traumato. Jul 2006;27:14–17.

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: Apport de l’imagerie au diagnostic du kyste hydatique de la paroi thoracique. J. Radiol. Mar 2003;84:143–146. 12717286

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10.5256/f1000research.169947.r336415

Reviewer response for version 1

Chaari

Zied

1 Referee https://orcid.org/0000-0002-4006-4055 1Department of Thoracic and Cardiovascular Surgery, Universite de Sfax, Sfax, Sfax, Tunisia

Competing interests: No competing interests were disclosed.

6 11 2024

2024

This is an open access peer review report distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

recommendation

reject

I have read this manuscript entiteled "Chest Wall Hydatid Disease: Surgical management and risk Factors for Recurrence and Mortality" with a lot of interest

This paper was about the chest wall localizations of hydatid disease and aimed to determine the results of its surgical management and to analyze the factors of recurrence and mortality through a multicentric and retrospective study including a total number of 49 patients.

This study included several centers including 4 surgical and 2 medical centers, which gives an idea of the rarity of this clinical entity of hydatidosis affecting the chest wall.

But, several points should be raised:

Abstract section :

- The interest of your study should be apparent from the introduction and background. Indeed, the problem of hydatidosis of the chest wall implies an increased risk of locoregional recurrences, as has been presented in some series.

Introduction section :

- In the introduction section, the authors reported that "The long symptomatic silence of this disease..." it would be better to detail if you are talking about hydatidosis in general (including pulmonary localizations which are often asymptomatic as reported in your text), or hydatid localizations particularly those of chest wall? if so, please report some references that cite the asymptomatic nature of hydatid localizations of the chest wall.

- "Bone lesions are extensive with a very progressive evolution and can lead to definitive neurological complications." Same remark about this sentence! the authors are dealing with (Bone) localization of hydatidosis or vertebral ones? hydatid involvement can very well be located in the long bones of the body, intraosseously, or even develop in the spongy bone, without having neurological complications as you mentioned!

- The entire introduction section did not really reveal the resulting study objectives. Indeed, the concept of hydatid recurrence only appears in this sentence without insisting on it (admittedly very important to describe from an epidemiological point of view, frequency in the general population, and especially to introduce your major objective of your study). Please provide more information, references that support the need for your study.

This definition was given in the Methods section but there is a lack of precision regarding the definition of the word "soft tissue". A localization at the level of the soft tissues of the thorax was defined on what extent? from the neck to the abdomen? for the anterior localizations what was the limit attributed? for the posterior localizations was it a limit up to the level of the 12th rib or the vertebrae...? Please provide more details.

Methods section :

- "Fifty records were retrieved." This sentence is a result, it should not be in the methods section.

- Same remark for the Abstract section. In this section, the authors would do better to clarify the definition of the term "chest wall" for inclusion of patients. For example: were clavicular, breast, intramedullary lesions in case of vertebral localization,... included?

- chest wall hydatidosis (CWH) abreviation was used and presented in the Methods section, and should be used towards the rest of the text. Please correct.

- same remark about Hydatid Cyst abreviation (HC) used in Methods section while this abbreviation was stated more recently in the introduction part of the manuscript. Please make corrections.

- Posterolateral thoracotomy abreviation does not figure in the text. It was first cited in Table 2 (without explanation at the bottom of the Table), and in discussion Section as (PLT) without explanation. Authors can use this abreviation for all "Posterolateral Thoracotomy" in the text.

- "We applied the inclusion and non-inclusion criteria and eliminated incomplete and unusable records. We retained fortynine patients operated on for chest wall hydatidosis." This section is a result. Please insert it in results section to apply inclusion, noninclusion and exclusion criteria.

Results Section :

- "During the study period, 49 patients were operated on for CWH. The mean age of our population was 41 ? 17 years [8-76 years] with a male predominance.". Authors can add the sex ratio for sex predominance, or put a reference to Table 1.

- Authors used abreviation in Table 1 that are not explained at the bottom of the Table. Please add abreviation explanations.

- Table 1 would be much more informative if the clinical signs were divided according to hydatid locations. Indeed, it is difficult to define and guess the clinical manifestations secondary to costal, bone, vertebral, or soft tissue involvement. Were there neurological manifestations for patients with isolated costal locations? Same remark for soft tissue involvement? Were the nervous manifestations exclusively secondary to vertebral hydatidosis?

- Table 1: The radiological characteristics presented in the table would lack precision. Did the exploration interest all patients? All radiological explorations (thoracic X-ray, rib grill, ultrasound, MRI, scanner... were carried out for all patients?). It would be better to specify the % of patients who had explorations according to their achievements or not.

- "Abdominal ultrasound was performed in 44 cases as part of the etiological and extension assessment of the hydatid disease and showed a hepatic HC (GHARBI type IV) in nine cases." Since the authors did not mention in the methods section the bases of the Gharbi classification stated in the text, a reminder of this definition is necessary in the methods section beforehand. Otherwise, an insertion of a reference that describes this classification could be an option.

- "Atiered involvement of more than two ribs was observed in 43% of the cases, with a predominance of lesions at the Fourth to ninth rib level." Can the authors specify the exact percentage of this predominance? in the general population studied, and within the group of costal injuries. This would be much more informative.

- I am afraid that there would be a miscalculation of the respective numbers of patients. Indeed, at the beginning of the Results section, the authors claimed to have reported 32 cases of vertebral localizations (between 11 exclusively vertebral cases, and 21 cases of costovertebral involvement). Further in the Results section, they mention "The vertebral involvement was in the vertebral body in 21 cases and the intervertebral disc in two cases." which makes 23 cases.

The results announced in the text are also in contradiction with those presented in Table 2 in which we find 11 costovertebral localizations (announced as 21 cases previously in the text). As well as the gestures involving the vertebrae (body, or transverse processes, or laminectomy), we can count 31 cases of gestures while in the text it was presented as 32 cases! (I quote: "Bone involvement was vertebral (n=11), only costal (n=12), costovertebral (n=21) and sternal (n=2)."

Do the authors have any explanations for this difference?

- "A primordial time is the protection of the operating field by a scolicide solution. The main solutions were hypertonic saline and hydrogen peroxide (Figure 3)." Figure 3 referred to by the authors does not show any scolicidal solution used during the surgical procedure. In addition, there is a lack of precision regarding the numbers (or %) of solutions used for the patients in this series.

- "The average length of hospitalization was 23.5 [5-55] days for isolated vertebral involvement, 19.8 [4-123] days for costovertebral involvement, 8.3 [1-35] days for isolated rib involvement, and three days for exclusive muscular involvement of hydatid disease." . Given the extreme values of hospitalization durations given in the text, the expression of the results would be better adapted by using the medians with the inter-quartille spaces 25% and 75% to have an idea on the median durations of hospitalizations. Please correct.

- This study was analytical in order to determine the possible recurrence factors associated with surgery for chest wall hydatidosis. This characteristic was revealed in the Results section. Please mention the study character in the Methods section.

- In the analytical part of the Results section, Table 3 included the univariate results of the possible factors associated with early recurrence. surprising results about Complete Costal resection that recur more quickly than a partial resection? Same thing for patients who had antiparasitic treatment postoperatively recur more quickly?

- The authors were supposed to analyze the factors related to perioperative mortality in Table 4, while in the table, we find delays to death! All deaths were secondary to complications directly related to hydatid pathology? All cases of deaths reported (with delays even reaching 24 years for some patients) were directly involved in parietal hydatidosis?

The analytical study to determine mortality factors should focus primarily on cases of death that were directly related to the pathology itself.

Discussion section :

- "Recurrence is considered a poor prognostic factor in chest wall hydatid (CWH) disease"... The abbreviation CWH has already been cited in the text, authors can use it without having to repeat the meaning of this abbreviation in the Discussion section.

- "This may be attributed to the small number of patients in our series (Ref 26)". I think that you meant "Their series referring to Todorov et al. study ?

- The Discussion section should be better organized, initially talking about hydatid involvement of the chest wall in general, then, the authors can focus on each compartment separately, given their specificities, and especially the difference in surgical management according to their respective locations.

- The authors did not explain the paradoxical results obtained concerning complete costal resection of hydatid lesions, which would be more likely to cause recurrences than partial resections?

- There are other articles that have looked at the study of factors of recurrence of spinal surgery, and published recently like this study which traces the factors of recurrence in 39 operated patients. It would be interesting to compare your results with this recent series and therefore include it in your list of references. (Ref:1)

- by well-organizing the discussion section, the authors can compare their results with similar series according to hydatid locations (the entire chest wall included, costal involvement, vertebral, costovertebral involvement, and soft tissue locations). This last location was not clearly discussed in the Discussion section (there is this reference that talks about it (Ref:2 ). Several series in the literature have studied and reported their results regarding spinal or vertebral hydatidosis with considerable numbers ( Ref:3, 4 and 5)

Statistics :

- Statistical revision must be made to correct Tables / the Text.

- The expression of Means / Medians / Effectives and % should be revised according to the normality of distribution.

Is the work clearly and accurately presented and does it cite the current literature?

Partly

If applicable, is the statistical analysis and its interpretation appropriate?

Are all the source data underlying the results available to ensure full reproducibility?

Partly

Is the study design appropriate and is the work technically sound?

Partly

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Partly

Reviewer Expertise:

Thoracic surgery / Chest wall Surgery / Hydatidosis / Lung and thoracic hydatidosis / Methodology / Statistics

I confirm that I have read this submission and believe that I have an appropriate level of expertise to state that I do not consider it to be of an acceptable scientific standard, for reasons outlined above.

References 1

: Surgical outcome and prognostic factors for 39 recurrent spinal hydatid cysts. Surg Neurol Int .2023;14: 10.25259/SNI_667_2023 347

37810304

10.25259/SNI_667_2023

: Primary Soft Tissue Hydatid Cysts. Turkiye Parazitol Derg .2022;46(2) : 10.4274/tpd.galenos.2021.03511 145-149

35604194

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: Multiple debridement of cavity lesions combined with antiparasitic chemotherapy in the treatment of mid or advanced spinal echinococcosis: a retrospective study of 33 patients. Int J Infect Dis .2022;114: 10.1016/j.ijid.2021.11.014 261-267

34775114

10.1016/j.ijid.2021.11.014

: Spinal manifestation of hydatid disease: a case series of 36 patients. World Neurosurg .2013;80(5) : 10.1016/j.wneu.2013.06.013 620-6

23851216

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: Vertebral hydatid disease. Clinical experience with 27 cases. J Neurosurg .1976;44(1) : 10.3171/jns.1976.44.1.0072 72-6

1244436

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Rouis

Houda

Department 3, Abderrahmen Mami Pneumology and Phthisiology Hospital, Ariana, Ariana, Tunisia

Competing interests: No competing interests were disclosed.

19 9 2025

Abstract section

Comment 1 :

- In this section, the authors would do better to clarify the definition of the term "chest wall" for inclusion of patients. For example: were clavicular, breast, intramedullary lesions in case of vertebral localization,... included? - The interest of your study should be apparent from the introduction and background. Indeed, the problem of hydatidosis of the chest wall implies an increased risk of locoregional recurrences, as has been presented in some series.

Thank you for your thoughtful comments. We would like to clarify that the anatomical definition of the "chest wall" is explicitly stated in the introduction of the revised manuscript. It includes lesions involving the ribs, intercostal muscles, sternum, and paravertebral soft tissues. Lesions of the clavicle, breast, and intramedullary vertebral structures were not included, as they fall outside our defined scope.

Due to word count limitations in the abstract, we provided a concise and precise summary, but the full anatomical definition is clearly detailed in the introduction to guide patient inclusion criteria.

Additionally, we have reinforced the introduction and background to better highlight the clinical significance of chest wall hydatidosis, particularly its association with increased locoregional recurrence risk, as noted in previous series.

We appreciate your valuable feedback, which has helped us improve the clarity and depth of our manuscript.

CWH refers to the presence of hydatid cysts caused by the tapeworm echinococcus granulosus within the anatomical structures of the chest wall including ribs and cartilages, sternum, thoracic vertebrae and muscles of the Chest wall (intercostal muscles, Pectoralis Major, Perctoralis Minor and Serratus anterior). We excluded the diaphragm as it is a distinct entity that will be investigated seperately in a subsequent article deserving its own dedicated study.

Introduction section :

Comment 1 :

Thank you for this pertinent observation. In the introduction, the phrase "The long symptomatic silence of this disease..." refers to hydatidosis in general, including pulmonary localizations, which are often asymptomatic and may remain undetected for extended periods. We have clarified this point in the revised manuscript to avoid ambiguity.

5. Durhan G, Tan AA, Akkaya İ, Bayramoğlu Z, Savaş R. Radiological manifestations of thoracic hydatid cysts: pulmonary and extrapulmonary findings. Insights Imaging . 2020;11(1):116. doi:10.1186/s13244-020-00916-0

3. Boudaya MS, Zairi A, Ayadi K, Abdennebi S, Touinsi H, Mestiri I, et al. Chest wall hydatidosis: a single institution experience. Arch Clin Infect Dis. 2016;11(2):e21015. doi:10.5812/archcid.21015

Comment 2 :

- "Bone lesions are extensive with a very progressive evolution and can lead to definitive neurological complications." Same remark about this sentence! The authors are dealing with (Bone) localization of hydatidosis or vertebral ones? Hydatid involvement can very well be located in the long bones of the body, intraosseously, or even develop in the spongy bone, without having neurological complications, as you mentioned!

In the sentence, "Bone lesions are extensive with a very progressive evolution and can lead to definitive neurological complications," we intended to refer specifically to vertebral hydatid disease, where the proximity to neural structures often results in neurological complications due to spinal cord compression or nerve root involvement.

We acknowledge that hydatid disease can also affect long bones and other intraosseous sites, where neurological complications are not typically observed.

To clarify this distinction, we have revised the sentence in the manuscript to specify that the described progression and neurological impact pertain to vertebral localizations.

Comment 3 :

We have now revised the introduction to explicitly present the study’s aim and to better contextualize the issue of recurrence, which is central to our retrospective multicenter analysis.

Chest wall hydatidosis poses unique therapeutic challenges, and recurrence remains a major concern with significant clinical implications.

Thank you for highlighting the need to better justify the relevance of our study. We have now clarified in the introduction that chest wall hydatid disease is a rare and poorly documented entity, with distinct diagnostic and therapeutic challenges compared to more common localizations. Our retrospective multicenter study—spanning nearly three decades and involving four university hospitals—aims to fill this gap by analyzing surgical outcomes and identifying risk factors for recurrence and mortality.

Methods section :

Comment 1:

- On the other hand, I am afraid that the concept of "chest wall" reported in the introduction section would require more explanations, definitions... Indeed, the authors should clarify the terminology of this clinical entity as well as its characteristics. This definition was given in the Methods section but there is a lack of precision regarding the definition of the word "soft tissue". A localization at the level of the soft tissues of the thorax was defined on what extent? from the neck to the abdomen? for the anterior localizations what was the limit attributed? for the posterior localizations was it a limit up to the level of the 12th rib or the vertebrae...? Please provide more details.

We acknowledge that the definition of "chest wall" and its anatomical boundaries should be more clearly stated in the introduction to avoid ambiguity.

In the revised manuscript, we have now included a more precise definition of the chest wall in the Introduction section, complementing the details already provided in the Methods.

Specifically, we define the chest wall as including the osseous structures (ribs, sternum, costal cartilages), intercostal muscles, and adjacent soft tissues, excluding breast tissue and clavicle.

Regarding soft tissue involvement, we considered lesions located within the muscular and subcutaneous layers of the thoracic wall, bounded:

Superiorly by the clavicle and thoracic inlet (excluding cervical and supraclavicular regions),

Inferiorly by the costal margin and 12th rib, without extending into the abdominal wall,

Anteriorly up to the sternum, excluding breast tissue,

Posteriorly to the paravertebral muscles, without extension into the vertebral canal unless explicitly associated with vertebral hydatidosis.

Comment 2:

- "Fifty records were retrieved." This sentence is a result, it should not be in the methods section.

- chest wall hydatidosis (CWH) abreviation was used and presented in the Methods section, and should be used towards the rest of the text. Please correct.

- same remark about Hydatid Cyst abreviation (HC) used in Methods section while this abbreviation was stated more recently in the introduction part of the manuscript. Please make corrections.

Please find below our detailed responses and the corresponding revisions:

Regarding the abbreviation CWH (Chest Wall Hydatidosis): We have revised the manuscript to introduce this abbreviation at its first mention in the Introduction, and it is now used consistently throughout the text.

Regarding the abbreviation HC (Hydatid Cyst): We have corrected the placement of this abbreviation, ensuring it is introduced in the Introduction and used uniformly across the manuscript.

Regarding the abbreviation PLT (Posterolateral Thoracotomy): We have added a definition of this abbreviation at its first appearance in the main text, and included a footnote explanation in Table 2. The abbreviation PLT is now used consistently throughout the manuscript .

Regarding the sentence "We applied the inclusion and non-inclusion criteria...": This section should be methods, where we now specify that 49 patient records were retained after applying the inclusion and exclusion criteria.

Results Section :

Comment 1:

- Authors used abreviation in Table 1 that are not explained at the bottom of the Table. Please add abreviation explanations.

Thank you for your detailed and constructive feedback regarding the Results section and Table 1. We have carefully reviewed each point and made the following revisions:

Sex ratio and reference to Table 1: We have added the sex ratio to the text to illustrate the male predominance better. Additionally, we now refer explicitly to Table 1 for demographic details.

Abbreviations in Table 1: All abbreviations used in Table 1 have now been explained in a footnote at the bottom of the table to ensure clarity for the reader.

Clinical signs by hydatid localization: We agree that distinguishing clinical manifestations by anatomical localization adds value. In the text, we now specify that:

Neurological manifestations were observed exclusively in patients with vertebral involvement.

Patients with isolated costal or soft tissue involvement did not present with neurological symptoms, but rather with localized pain or swelling.

Radiological characteristics and exploration details: We have clarified that not all patients underwent the same radiological investigations. We include the percentage of patients who underwent each imaging modality (e.g., thoracic X-ray, CT scan, MRI, ultrasound). This provides a more precise overview of the diagnostic approach used across the cohort.

Comment 2:

- " Abdominal ultrasound was performed in 44 cases as part of the etiological and extension assessment of the hydatid disease and showed a hepatic HC (GHARBI type IV) in nine cases." Since the authors did not mention in the methods section the bases of the Gharbi classification stated in the text, a reminder of this definition is necessary in the methods section beforehand. Otherwise, an insertion of a reference that describes this classification could be an option.

The Gharbi classification applies specifically to hepatic involvement and not to thoracic wall involvement, which is the primary focus of our study. However, we have included a reference for readers who may be interested in learning more about this classification.

6. Gharbi HA, Hassine W, Brauner M, Dupuch K. Ultrasound examination of the hydatic liver. Radiology. 1981;139(2):459–63

Comment 3:

The involvement of the intervertebral disc in two cases was not isolated; it was associated with vertebral body involvement. Our intention in mentioning these cases was to enumerate the different anatomical sites affected, rather than to suggest distinct patient counts. Given the extensive nature of the bone lesions, it is often difficult to clearly separate the affected structures.

The thoracic CT scan was performed in 94% of cases (Table 1). Costal damage was in the posterior arch in 25 cases (51%). A tiered involvement of more than two ribs was observed in 43% of the cases, with a predominance of lesions at the Fourth to ninth rib level. The vertebral involvement was in the vertebral body in 21 cases and the intervertebral disc in two cases. In addition we observed that the vertebral involvement appeared as an ossifying abscesses in the vertebral arch, pedicles, laminae and transverse processes in 11 cases. In fact , the involvement was difficult to isolate to each component of the vertebra due to the extension and dissemination within the bone as there was no cystic wall to limit the lesions.

In 16% of cases, the number of affected vertebrae was two or more. The most affected levels were D7-D9 (n=11) explained by the richness of the vascularization of this spine segment (Figure 1D, Figure 2).

Comment 4:

In the same context, regarding costovertebral lesions (in the number expressed as 21 cases at the beginning of the Results section), the number of operated cases described was 18! (According to what was announced in the text: "All patients were operated on. For costovertebral involvement, posterolateral thoracotomy was performed in 11 cases (61% of cases), a posterior approach in four cases (22% of cases), and a combined approach in 3 cases (17% of cases) The results announced in the text are also in contradiction with those presented in Table 2 in which we find 11 costovertebral localizations (announced as 21 cases previously in the text). As well as the gestures involving the vertebrae (body, or transverse processes, or laminectomy), we can count 31 cases of gestures while in the text it was presented as 32 cases! (I quote: "Bone involvement was vertebral (n=11), only costal (n=12), costovertebral (n=21) and sternal (n=2)." Do the authors have any explanations for this difference?

Thank you for your careful and detailed analysis of our data presentation.

We would like to clarify that the numbers reported for surgical procedures and anatomical involvement are not strictly additive, as some patients underwent multiple procedures or had overlapping anatomical localizations. For example, in cases of costovertebral involvement, the surgical approach varied depending on the extent and accessibility of the lesions. Some patients required combined approaches, and others had multifocal bone involvement, which may have included both vertebral body and transverse process procedures. This overlap explains why the number of surgical gestures may appear to exceed or differ from the number of patients

Comment 5:

We would like to clarify that Figure 3 illustrates the use of scolicidal solution through the surgical fields soaked with impregnated gauze, which is the standard technique used to protect the operating area during hydatid cyst surgery. While the solution itself is not directly visible in the image, the gauze shown in the figure is saturated with scolicidal agents, specifically hypertonic saline or hydrogen peroxide, as described in the text.

To address your second point, we have now added specific data regarding the use of scolicidal solutions in our series. Hypertonic saline was used in 36 cases (73%), and hydrogen peroxide in 13 cases (27%). This information has been included in the revised manuscript to improve clarity and completeness.

Comment 6:

- " The average length of hospitalization was 23.5 [5-55] days for isolated vertebral involvement, 19.8 [4-123] days for costovertebral involvement, 8.3 [1-35] days for isolated rib involvement, and three days for exclusive muscular involvement of hydatid disease." . Given the extreme values of hospitalization durations given in the text, the expression of the results would be better adapted by using the medians with the inter-quartille spaces 25% and 75% to have an idea on the median durations of hospitalizations. Please correct.

We agree that median values accompanied by interquartile ranges (IQRs) provide a more accurate representation of hospitalization durations, especially in the presence of extreme values. In response to your comment, we have recalculated and updated the data accordingly:

Isolated vertebral involvement: median 21 days [IQR: 12–32]

Costovertebral involvement: median 15 days [IQR: 9–26]

Isolated rib involvement: median 6 days [IQR: 3–11]

Exclusive muscular involvement: median 3 days [IQR: 2–4]

These revised figures have been incorporated into the manuscript to enhance the clarity and statistical relevance of our findings

Comment 7:

We would like to clarify that the analytical nature of the study was indeed described in the Methods section, specifically under the subsection detailing the statistical approach. We have now further emphasized this aspect by explicitly stating that the study was designed as an analytical observational study, aiming to identify potential factors associated with early recurrence following surgery for chest wall hydatidosis.

Regarding the second point, we acknowledge that the results in Table 3—particularly the association of complete costal resection and postoperative antiparasitic treatment with earlier recurrence—may appear unexpected. However, as noted in the Discussion section, these findings were interpreted with caution and may be influenced by the limited size of our cohort, which can affect statistical robustness and lead to apparent paradoxes.

We have emphasized in the manuscript that complete resections and antiparasitic treatments were often applied in more severe or complex cases, which may inherently carry a higher risk of recurrence. These variables may therefore reflect underlying disease severity rather than being independent risk factors.

Comment 8:

We would like to clarify that, due to the retrospective nature of our study, it was not always possible to determine with certainty whether all reported deaths were directly related to chest wall hydatidosis. Patients were contacted retrospectively by telephone, and in several cases, the exact cause of death could not be confirmed, especially when the delay extended over many years.

Our intention in presenting Table 4 was to report the time to death following surgery, as part of the long-term follow-up, rather than to imply direct causality in all cases. We agree that a more focused analysis on perioperative and disease-related mortality would be ideal, but the limitations inherent to retrospective data collection constrained our ability to do so with precision.

Discussion section

Comment 1 :

" Recurrence is considered a poor prognostic factor in chest wall hydatid (CWH) disease"... The abbreviation CWH has already been cited in the text, authors can use it without having to repeat the meaning of this abbreviation in the Discussion section.

done

Comment 2 :

- "This may be attributed to the small number of patients in our series (Ref 26)". I think that you meant "Their series referring to Todorov et al. study ?

Thank you very much for your detailed and constructive feedback.

Regarding your first point, we confirm that the reference to the small number of patients in our series was indeed about our own cohort, not Todorov et al.’s study. We have clarified this in the revised text to avoid confusion.

As you rightly noted, most published studies are descriptive rather than analytical, and the few analytical ones tend to focus on spinal hydatid disease, which includes vertebral and costovertebral involvement, rather than isolated chest wall hydatidosis, particularly soft tissue involvement. Our objective was to estimate potential risk factors for recurrence and complications in this rare location, but due to the limited sample size, we acknowledge that our findings cannot be generalized. We have emphasized this limitation more clearly in the revised discussion.

We appreciate your suggestion to reorganize the Discussion section. We have now structured it to first address hydatid involvement of the chest wall in general, followed by a compartmental analysis (costal, vertebral, costovertebral, and soft tissue), highlighting the specific surgical approaches and outcomes associated with each.

Comment 3 :

- The authors did not explain the paradoxical results obtained concerning complete costal resection of hydatid lesions, which would be more likely to cause recurrences than partial resections?

Concerning the paradoxical results regarding complete versus partial costal resections, we agree that this point requires clarification. We have added a discussion on the possible selection biais and underlying lesion extent, which may have influenced the recurrence rates despite more aggressive resections.

Comment 4 :

- by well-organizing the discussion section, the authors can compare their results with similar series according to hydatid locations (the entire chest wall included, costal involvement, vertebral, costovertebral involvement, and soft tissue locations). This last location was not clearly discussed in the Discussion section (there is this reference that talks about it . Several series in the literature have studied and reported their results regarding spinal or vertebral hydatidosis with considerable numbers.

We also appreciate the reference to soft tissue hydatid cysts , which was not sufficiently discussed in our original manuscript. We have now expanded this section to include relevant literature and better contextualize our findings.

10. Patmano M, Çetin DA, Gümüş T, Patmano G, et al.: Primary Soft Tissue Hydatid Cysts.Turkiye Parazitol Derg. 2022; 46 (2): 145-149 .

A recent study of eight cases of primary soft tissue hydatid cysts highlighted various locations, with 25% occurring in the left posterior thoracic region, a rarely reported site [10]. The management of hydatid cysts located in soft tissues remains challenging due to their rarity and potential for misdiagnosis. Complete surgical excision is the cornerstone of treatment. These findings align with the general principle that careful surgical management is critical, particularly for unusual and anatomically complex locations such as the posterior thoracic wall.

The additional references (Refs 24, 25, and 26) have been reviewed and incorporated where appropriate to enrich the comparative analysis across different chest wall compartments.

24. Luan H, Liu K, Deng Q, Sheng W, et al.: Multiple debridement of cavity lesions combined with antiparasitic chemotherapy in the treatment of mid or advanced spinal echinococcosis: a retrospective study of 33 patients.Int J Infect Dis. 2022; 114: 261-267

25. Kafaji A, Al-Zain T, Lemcke J, Al-Zain F: Spinal manifestation of hydatid disease: a case series of 36 patients.World Neurosurg. 2013; 80 (5): 620-6

26. Apt WL, Fierro JL, Calderon C, Perez C, et al.: Vertebral hydatid disease. Clinical experience with 27 cases.J Neurosurg. 1976; 44 (1): 72-6

Luan et al. [24] reported a combined therapeutic strategy involving repeated surgical debridement and prolonged antiparasitic treatment with albendazole in patients with advanced vertebral hydatidosis. Although this approach aims to reduce parasitic load and limit disease progression, the authors observed a significant recurrence rate, often requiring repeated surgeries and long-term follow-up. Similarly, Kafaji et al. [25] highlighted the technical challenges of spinal surgery in this context, frequently incomplete due to the infiltrative nature of hydatid cysts within vertebral structures. They also noted the limited efficacy of antiparasitic drug therapy alone, with a high postoperative recurrence rate. The earlier observations by Apt et al. [26] reinforce these findings, reporting frequent recurrences even decades ago, often associated with severe neurological complications. Despite differences in clinical context and time period, these studies consistently emphasize the infiltrative and recurrent nature of vertebral hydatidosis, which continues to make curative treatment particularly challenging.

Comment 5 :

Thank you for pointing out the recent study on spinal hydatid recurrence (34). We have now included this reference and compared our findings with theirs, while acknowledging the differences in anatomical location and surgical complexity.

34. Obame FLO, Dokponou YCH, Mohcine S, Elmi SM, et al.: Surgical outcome and prognostic factors for 39 recurrent spinal hydatid cysts.Surg Neurol Int. 2023; 14: 347

In the management of recurrent spinal hydatid cysts, surgical outcomes remain variable with a significant risk of recurrence. A recent study analyzing 39 cases of recurrence identified several major prognostic factors influencing postoperative outcomes [34]. Intraoperative cyst rupture was found to be significantly associated with an increased risk of recurrence (p = 0.001). Similarly, subtotal resection, often necessitated by the infiltrative nature of the lesions, correlated with a significantly higher risk of recurrence (p < 0.007). Thoracic localization of the cysts and the performance of laminectomy were also identified as independent factors associated with poorer prognosis (p < 0.04). These findings highlight the importance of complete and careful resection, as well as meticulous management of intraoperative rupture risks, to optimize clinical outcomes and reduce recurrence rates. These factors should be carefully considered in the therapeutic planning and follow-up of patients with vertebral hydatidosis.

10.5256/f1000research.169947.r336420

Reviewer response for version 1

Mihetiu

Alin

1 Referee Vintila

Bogdan

2 Co-referee 1Hospital of Sibiu, Lucian Blaga University of Sibiu, Sibiu, Romania 2Anesthesiology, Lucian Blaga University of Sibiu Faculty of Medicine (Ringgold ID: 202855), Sibiu, Sibiu, Romania

Competing interests: No competing interests were disclosed.

5 11 2024

2024

recommendation

approve

The article is a good addition to previous literature regarding this disease.

The structure is well organized and homogenous with a satisfactory statistical analysis.

The discussion part provides additional data that reinforce the findings from the study.

In my opinion the article has sufficient arguments to be published due to lack of large studies on this topic.

Is the work clearly and accurately presented and does it cite the current literature?

Yes

If applicable, is the statistical analysis and its interpretation appropriate?

Yes

Are all the source data underlying the results available to ensure full reproducibility?

Yes

Is the study design appropriate and is the work technically sound?

Yes

Are the conclusions drawn adequately supported by the results?

Yes

Are sufficient details of methods and analysis provided to allow replication by others?

Yes

Reviewer Expertise:

General Surgery

We confirm that we have read this submission and believe that we have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.