Urine cytological examination: an appropriate method that can be used to detect a wide range of urinary abnormalities

Introduction

Urine cytology is a safe and inexpensive method to diagnose urinary tract abnormalities. It is similarly used for the detection of primary and recurrent urothelial carcinoma^1,2; as well as in many other diseases related to the urinary system such as urinary schistosomiasis³ and bacterial infections⁴. Urine cytology has variable sensitivity and specificity depending on the sample collection method and tumor grade in the case of malignancy^5–7. Although the determination of cell morphology through microscopy remains the gold standard⁸, false positive and negative results have been reported. The false-positive results from urine cytology may be attributed to the presence of viral infections, such as polyomavirus. False negative results have been linked to the sampling method used, the number of the samples obtained from the patient and the volume of the urine being processed^1,6–10. Urothelial carcinoma is one of the most commonly reported cancers¹¹. The major clinical concern for the management of bladder cancer patients is that most of the patients relapse^12,13. Therefore, regular follow-up is required for patients who are at risk of urothelial carcinoma¹⁴. Despite many attempts to develop tests with higher sensitivity and specificity, cytology remains one of the best ways to diagnose a variety of bladder lesions¹⁵.

Hematuria is one of the common indications for urine cytology examination. It is also known to be caused by an underlying malignancy in 5% to 10% of patients¹⁶. Urine cytology is also used for the detection of abnormalities related to diseases like schistosomiasis³, candidiasis¹⁷, polyomavirus (BK virus (BKV)) infection^18,19, Human Papillomavirus (HPV)^20,21 and cryptococcosis²². In this study, we aimed at investigating the frequency of urine abnormalities among Sudanese patients attending the outpatient clinic at Omdurman Teaching Hospital, Khartoum, Sudan using urine cytology.

Methods

A descriptive cross-sectional study conducted from November 2016 to April 2017, an organized mass screening programme for urine cytology was introduced during the study period. The target screening population consists of the entire patients attending the outpatient’s clinic and agreed to participate in the study. A total of 1238 Patients were recruited from the outpatient clinic at Omdurman Teaching Hospital in Khartoum state, Sudan. All the patients attending the outpatients clinic were assessed by our research team and we discussed with all the patients the objective of our research. After obtaining written informed consent from the patients whom were willing to participate our research team gathered the patients information and demographic data including name, age, and any clinical signs or symptoms using a questionnaire, the process of filling and collecting the patients clinical data were conducted by our research team and it took place in the patients waiting area in the clinic, focusing on patients with HIV, diabetes mellitus and transplant recipients, and any patients with other conditions mentioned in the questionnaire.

Results

Analysis of urine cytology results based on patients’ age group

Regarding the relationship between age and cytological findings, our study showed that candida infection, Schistosomiasis, Polyoma virus and HPV were highest among the age group 41 – 60 years; while Cryptococcus infection was highest among 21 – 40 years old patients.

A representative microscopic result of urine cytology diagnosis is shown in Figure 1, and the distribution of gender, presence of hematuria, medical condition and urine cytology diagnosis based on age groups is described in Table 2.

Figure 1.

A: Cytopathic effect of human papilloma virus (HPV) with the eosinophilic intranuclear inclusion and a perinuclear halo and koilocytosis. B: Cryptococcus infection showed the organism with double contours. C: Polyomavirus cytopathic effect, the presence of decoy cells and pseudo hyphae and cells exhibit threads and small, round clumps of degenerating chromatin. D: Papillary cluster and single urothelial cells from low-grade urothelial cells. E: Cytological smears showed a monolayer sheet of cells with hyperchromasia and irregular distribution of chromatin and prominent nucleoli features of high-grade urothelial carcinoma. F: Schistosoma haematobium egg. G: Candida infection with bacterial. H and I: The counterpart diagnosis of D and E for the detected low-grade urothelial neoplasm and high-grade urothelial carcinoma using Hematoxylin and Eosin (H&E) histopathology staining (x40). H: Atypical urothelial cells. I: High-grade urothelial carcinoma showing very large, irregular and hyperchromatic nuclei. A–G: Staining using Papanicolaou stain (x100).

Table 2. Urine cytology diagnosis based on age groups of patients.

	Age group of Patients				Total	P value
	0–20 years	21–40 years	41–60 years	More than 60 years
Gender of Patients
Male	46 (5.5%)	365 (43.9%)	333 (40.0%)	88 (10.6%)	832 (67.2%)	0.00001
Female	0 (0.0%)	174 (42.9%)	189 (46.6%)	43 (10.6%)	406 (32.8%)
Presence of hematuria
Yes	3 (2.1%)	59 (40.7%)	58 (40.0%)	25 (17.2%)	145 (11.7%)	0.036
No	43 (3.9%)	480 (43.9%)	464 (42.5%)	106 (9.7%)	1093 (88.3%)
Medical condition
AIDS	1 (7.7%)	6 (46.2%)	3 (23.1%)	3 (23.2%)	13 (1.1%)	0.0001
Diabetic	0 (0.0%)	25 (36.2%)	37 (53.6%)	7 (10.1%)	69 (5.6%)
Renal transplant	1 (1.5%)	12 (18.5%)	40 (61.5%)	12 (18.5%)	65 (5.3%)
No Condition	44 (4.0%)	496 (45.5%)	442 (40.5%)	109 (10.0%)	1091 (88.1%)
Urine cytology diagnosis
Candidiasis	3 (7.0%)	16 (37.2%)	19 (44.2%)	5 (11.6%)	43 (3.5%)	0.0001
Cryptococcosis	0 (0.0%)	6 (54.5%)	5 (45.5%)	0 (0.0%)	11 (0.9%)
Human papilloma virus	0 (0.0%)	0 (0.0%)	8 (88.8%)	1 (11.1%)	9 (0.7%)
Schistosomiasis	0 (0.0%)	1 (16.6%)	5 (83.3%)	0 (0.0%)	6 (0.5%)
Polyomavirus	0 (0.0%)	3 (37.5%)	5 (62.5%)	0 (0.0%)	8 (0.6%)
Urothelial carcinoma	0 (0.0%)	0 (0.0%)	4 (44.4%)	5 (55.6%)	9 (0.7%)
Reactive Urothelial cells	0 (0.0%)	17 (47.2%)	13 (36.1%)	6 (16.7%)	36 (2.9%)
Low grade urothelial cells	0 (0.0%)	1 (33.3%)	0 (0.0%)	2 (66.7%)	3 (0.2%)
Normal	43 (3.9%)	495 (44.5%)	463 (41.6%)	112 (10.1%)	1113 (89.0%)

Discussion

Urine cytology is considered a noninvasive, cost effective technique that is able to diagnose a wide range of abnormalities including infections, atypical cellular changes and malignancy^26,27. However, in this study, we investigated a varied array of urine abnormalities among Sudanese patients attending the outpatient clinic at Omdurman Teaching Hospital, Khartoum-Sudan using urine cytology.

In this study, we observed that urine cytology could easily differentiate benign from malignant cells showing high specificity for detecting HGUC; this result agrees with previous reports^8,28–30. HGUC are aneuploid and are detected with high sensitivity, as compared to atypical urothelial cells^29–31. The cytological features of HGUC identified in this study showed that the smears exhibited high cellularity and dehiscence cellular pattern. Malignant cells were larger than normal cells and showed pleomorphic nuclei with prominent nucleoli. Also, the cytoplasm ranged from homogenous to scant vacuolated one. Depending on these features, previous studies have indicated that detection of malignant cells using urine cytology is the gold-standard method for diagnosing urothelial cancer.^2,29,32.

In this report we are also able to identify Candida spp with great confidence by the presence of the budding yeast and pseudohyphae which is considered as the cytomorphological characteristic of this fungus, however if the organism was not identified, cytological changes such as stain anomaly, nuclear degeneration and bacterial background may pinpoint the presence of candida.

Cryptococcus infection was detected in 2 out of 13 HIV patients; 0 out of 69 DM2 patients and 2 out of 65 renal transplant recipients. The organism was correctly identified by the presence of a semitransparent fungal organism with double contours in an inflammatory background^22,31,33.

Polyoma virus (BKV) was detected in 0 out of 13 (0%) HIV positive patients; 2 out of 69 (2.89%) DM2 patients and 6 out of 65 (9.2%) renal transplant recipients. The key feature for the existence of polyomavirus is depending on the presence of the unique cytomorphological features, i.e., presence of the typical decoy cells, the nuclei of this cell appeared as uniform with washed chromatin^34–42. The results obtained by this study demonstrated that urine cytology can be used as a simple monitoring test for the renal transplant recipient for the presence of polyoma virus, since polyoma virus infection in renal transplant recipient is considered as one of the factors that can lead to graft rejection^42–48. Our results are in concordance to that conducted by Kapila and his associates; they investigated the diagnostic efficacy of urine cytology in detecting Polyoma virus among renal transplant recipients comparing urine cytology with molecular diagnosis and their results showed that urine cytology can be used as an easy tool for monitoring the patients⁴⁹. Furthermore, our results showed that no polyoma virus was been detected among HIV patients, which is in contrast to the findings of Boldorini and his associates as they screened 78 patients with HIV for the presence of polyoma virus using urine cytological examination and molecular and immunohistochemistry, there results demonstrated that out of 78 patients, only 17 patients were positive for Polyoma virus using cytology⁵⁰.

Furthermore, Human papilloma virus was been detected among 9 out of 1238 (0.7%) of whom 8 were females and one was a male; the results obtained here should be evaluated with care especially in the settings of female individuals as it is very difficult if not impossible to differentiate whether these koilocytic cells originated from the urinary tract or they belong to the uterine cervix and therefore in such circumstances we highly recommend that these females should go for pap smear to locate the exact site of HPV infections.

Conclusion

Urine cytology is a safe, noninvasive, and reliable diagnostic tool for identifying viral cytopathic effects in urothelial cells, and deserves more widespread use in the monitoring of patients, especially those with renal transplants. It now seems that urine cytology needs to be implemented in clinical settings for the benefit of patients and urologists. Polyoma virus infection detection among transplant patients helps urologists to identify and manage renal graft rejection early which is of invaluable benefit to patients, physicians and economically. Due to the risk of the presence of polyoma virus among renal transplant recipient and based on the fact that 50% of the cases with Polyoma virus was associated with the graft rejection we highly recommended to use urine cytology as an early screening tool for routine checks among renal transplant patients. Furthermore, Pap staining was considered as an excellent cytological stain that provided excellent morphological quality for the visualization of the nuclear changes.

Ethics approval and consent to participate

The study was approved by the Faculty of Medical Laboratory Sciences Research Ethics Committee – University of Khartoum, Sudan (Nov/2016/102). Written informed consent was obtained from each participant prior to participation.

Data availability