Case Report: Leathery black plaque on the temple and scalp

Background Epidermal nevus sebaceous, commonly known as the nevus sebaceous of Jadassohn, is a congenital sebaceous hamartoma. It typically manifests as a single yellowish plaque across the head and neck and is composed of sebaceous glands. It commonly occurs during infancy and grows during puberty. Usually, it follows a benign course; however, in a few cases, it can be malignant. This is the case of a 13-year-old child with verrucous plaques on the temple and scalp. Case report We report the case of a 13-year-old boy with a steadily developing hyperpigmented verrucous plaque on the scalp and ipsilateral side of his face. A dermoscopic examination revealed ridges and fissures in a cerebriform pattern with yellowish-gray globules and a papillary appearance. Physical examination and laboratory tests revealed no abnormalities. Biopsies were taken from the scalp and temple area, and the findings were consistent with the diagnosis of nevus sebaceous. The patient was referred to a plastic surgeon for a staged excision. Conclusions We describe a unique example of a sebaceous nevus that affected the scalp and ipsilateral side of the face. As this hamartomatous growth carries the risk of cancer development, a dermatologist must identify the condition and begin treatment before malignant transformation occurs. This example of multiple verrucous plaques is an exception.

We report the case of a 13-year-old boy with a steadily developing hyperpigmented verrucous plaque on the scalp and ipsilateral side of his face.A dermoscopic examination revealed ridges and fissures in a cerebriform pattern with yellowish-gray globules and a papillary appearance.Physical examination and laboratory tests revealed no abnormalities.Biopsies were taken from the scalp and temple area, and the findings were consistent with the diagnosis of nevus sebaceous.The patient was referred to a plastic surgeon for a staged excision.

Conclusions
We describe a unique example of a sebaceous nevus that affected the scalp and ipsilateral side of the face.As this hamartomatous growth carries the risk of cancer development, a dermatologist must identify the condition and begin treatment before malignant transformation occurs.This example of multiple verrucous plaques is an exception.
Any reports and responses or comments on the article can be found at the end of the article.

Introduction
Nevus sebaceous (NS), initially described by Jadassohn, is a complicated hamartoma that typically develops on the face or scalp and has an epithelial or adnexal origin. 1 It can appear at birth or develop in infancy and increases during puberty, suggesting a hormonal influence.It can occasionally be found in other locations, such as the trunk or the oral or vaginal mucosa, although it mostly affects the scalp.Less frequently, it affects the preauricular area and neck. 2 Nevus sebaceous of Jadassohn (NSJ) develops in three stages.It manifests as isolated, well-circumscribed, smooth, yellowish plaques without hair during the infantile period.It becomes more noticeable with a verrucous or mamillated appearance during puberty.The last stage is characterised by peripheral telangiectasias and a nodular or tumoral appearance. 3gure 1.Verrucous plaque on frontal, temporal and preauricular area.(Written informed consent for publication of their clinical details and clinical images was obtained from the relatives of the patient).

REVISED Amendments from Version 1
We have added the differentiating points between the close differential diagnosis of Nevus Sebaceous, how to clinically identify the malignant transformation in the case of Nevus Sebaceous, and various non-invasive investigations for the same with genetics.
Any further responses from the reviewers can be found at the end of the article Many neoplasms develop alongside NS as proliferative growth begins.Both benign and malignant tumors have been reported to grow in NS.NS can be a site of basal cell cancer, syringocystadenoma papilliferum, trichoblastoma, and hidradenoma. 4se report A 13-year-old boy visited the dermatology outpatient department on 8 th September 2023 with a raised lesion on his scalp since birth and a lesion that had spread to the left side of the face over ten years.The ophthalmological, neurological, or cutaneous systems did not exhibit any abnormalities during physical examination.These skin lesions had not previously occurred in the family.The results of all laboratory tests, including the kidney function test, liver function test, urine examination, and complete blood count were within normal ranges.The patient had no other complaints.
On cutaneous examination, a well-demarcated hyperpigmented verrucous plaque with a size of 8 Â 4 cm was present on the frontal area of the scalp extending down to involve the forehead and a 7 Â 3 cm plaque was present on the temporoparietal area and left preauricular area [Figure 1].Based on the patient's medical history and physical examination, the possible differential diagnoses were identified as congenital melanocytic nevus, giant seborrhoeic keratoses, and verrucous epidermal nevus.However, a thorough examination through dermoscopy and histology conclusively ruled out these possibilities.In seborrheic keratosis, other than ridges and fissures multiple milia and comedone-like openings will be there.In acanthosis nigricans, there will be papillary projections with hyperpigmented dots and perifollicular pigmentation.We confirmed on clinical grounds that there were no clinical signs in the lesion to undergo a malignant transformation like ulceration, bleeding from the lesion or sudden increase in the size of the lesion.On dermoscopic examination, ridges and fissures were present in a cerebriform pattern with yellowish-grey globules and a papillary appearance [Figure 2].Histopathological examination revealed acanthosis, papillomatosis, and mild hyperkeratosis.There were immature and mature sebaceous glands with sebaceous hyperplasia and primitive hair follicles [Figure 3].The diagnosis of nevus sebaceous was established based on clinical presentation, dermoscopic findings, and histological analysis.The patient was referred to a plastic surgeon on 8 th September 2023 for a staged surgical excision of the nevus sebaceous.Our dermatology department does not offer plastic surgery services, hence the referral.Unfortunately, the patient was lost to follow-up after the referral, and we do not have any further information available.

Discussion
Nevus sebaceous is a condition that appears at birth and increases in size with age.The exact cause of this condition is still uncertain, but recent studies have shown that it may be linked to women who have tested positive for the human papillomavirus or carry mutations in the PTCH gene. 5,6vus sebaceous can present as one of the manifestations of Epidermal Nevus Syndrome.7 There are some hereditary syndromes, including didymosis aplasticosebacea and SCALP (sebaceous nevus, central nervous system malformations, aplasia cutis congenita, limbal dermoid, and pigmented nevus) syndrome, that may present nevus sebaceous as a symptom.This condition typically appears as a smooth, yellowish-orange, round, oval, or linear plaque, mostly on the scalp, leading to alopecia.5 A previous study found that nevus sebaceous can occur in multiple locations, similar to verrucous epidermal nevi. 8Nevus sebaceous is rarely reported in the literature to affect the scalp and ipsilateral side of the face.9 In our case, the scalp and the ipsilateral side of the face were affected.
Several discussions have taken place regarding the emergence of secondary benign and malignant tumors inside the nevus sebaceous.While basal cell carcinoma development has been documented by multiple authors in adults, recent reports have also identified atypical malignant neoplasms such as eccrine porocarcinoma, sebaceous carcinoma, apocrine carcinoma, and squamous cell carcinoma developing inside the NS. 10,11ere is a risk of developing malignant tumors in the Nevus Sebaceous.To detect these tumors accurately, non-invasive techniques like High-frequency Ultrasound and Reflectance Confocal Microscopy are used.These techniques help in visualizing the skin and skin appendages for accurate depth and lateral border detection.Reflectance Confocal Microscopy is particularly useful as it allows for in vivo evaluation of lesions and shows both anatomical features and individual cells. 12,13The presence of PTCH deletion, HRAS, and KRAS mutation can lead to malignant transformation in the nevus sebaceous. 14Although the timing of resection for nevus sebaceous therapy is debatable, most researchers feel that surgical excision is the preferred course of action.However, surgical excision to remove nevus sebaceous creates a linear scar.There are various therapeutic options, such as CO 2 laser therapy, to reduce scarring.However, CO 2 laser vaporization completely eradicates the sebaceous section of the nevus, which is located in the epidermis or papillary dermis. 15

Conclusions
The primary take-away lesson from our case is as follows: We describe a unique example of a sebaceous nevus that affected the scalp and ipsilateral side of the face.As this hamartomatous growth carries the risk of cancer development, a dermatologist must identify the condition and begin treatment before malignant transformation occurs.This example of multiple verrucous plaques is an exception.

Consent
Written informed consent for publication of their clinical details and clinical images was obtained from the relatives of the patient.
1. "As this hamartomatous growth carries the risk of cancer development, a dermatologist must identify the condition and begin treatment before malignant transformation occurs" Q: a) as the lesion is bigger, how did you confirmed that malignant transformation had not occurred in the lesion.what was the measures taken to identify malignancy change in the entire lesion.b) Was dermoscopy performed over the entire lesion!Was biopsy done on any suspicious part!Reviewer Expertise: Cell biology and therapeutic strategies of Large /giant congenital nevi and neurocutaneous melanocytosis.
I confirm that I have read this submission and believe that I have an appropriate level of expertise to confirm that it is of an acceptable scientific standard.

Figure 2 .
Figure 2. Ridges and fissures in a cerebriform pattern with yellowish grey globules and papillary appearance.

Figure 3 .
Figure 3.There are immature and mature sebaceous gland with sebaceous hyperplasia along with primitive hair follicles with acanthosis, acanthosis, papillomatosis and mild hyperkeratosis of epidermis.

4 ."
Several discussions have taken place regarding the emergence of secondary benign and malignant tumors inside the nevus sebaceous" Q: kindly mention for the readers, what are the possible clinical features that alerts the malignant change and its relevant investigations for early detection of local and systemic invasion with their likely management 5." As this hamartomatous growth carries the risk of cancer development, a dermatologist must identify the condition and begin treatment before malignant transformation occurs".Q: Malignant transformation was repeatedly emphasized in the article.So Mention the role of latest non-invasive skin imaging technique such as high-frequency ultrasound, multispectral imaging, optical coherence tomography, reflectance confocal microscopy etc. also mention a word on molecular/genetic study if reported earlier for early diagnosis of malignancy.Is the background of the case's history and progression described in sufficient detail?YesAre enough details provided of any physical examination and diagnostic tests, treatment given and outcomes?PartlyIs sufficient discussion included of the importance of the findings and their relevance to future understanding of disease processes, diagnosis or treatment?given and outcomes?Yes Is sufficient discussion included of the importance of the findings and their relevance to future understanding of disease processes, diagnosis or treatment?Partly Is the case presented with sufficient detail to be useful for other practitioners?Yes Competing Interests: No competing interests were disclosed.

On dermoscopic examination, ridges and fissures were present in a cerebriform pattern with yellowish-grey globules and a papillary appearance
" Q: a) several dermoscopic features were missed out.Dermoscopy is the key factor in this case.As the biopsy cant be done over the entire lesion, dermoscopy can bridge the gap between clinical and histopathological findings.b) ridges and fissures seen in several other conditions like seborrheic keratosis, acanthosis nigricans, nevus.So What was the classical features in this case.c) mention about the clods/globules of different sizes and shapes d) several clods are black (indicates keratinous plug), bright black dots/globules indicates that it communicate with surface, whereas the dull black are intraepidermal one.e) was the biopsy performed on the same dermoscopic site.d) mention other close dermoscopic differential diagnosis and one or two points on its differentiation.