ANALYSIS OF URINE CYTOLOGY AT A COMMUNITY HOSPITAL

Ibrahim Mansoor

Department of Pathology, St. John Hospital and Medical Center, Detroit.

Background: To review the pattern of urine cytology in our setting of a community hospital with age and gender distribution. Also to discuss the importance of this safe and inexpensive tool for diagnosing and screening urothelial cancers. We desire to encourage more wider and confident use of urine cytology in the routine practice. Method:  We reviewed all the consecutive urine cytology specimens received at our institution during time frame of one year. The cytological diagnosis were grouped in four categories; 1: negative, benign or reactive cases; 2: cases showing acute inflammatory changes; 3: inconclusive cases and 4: malignant cases. Only the positive malignant cases were followed histologically to determine the accuracy and efficiency of urine cytological examination for positive cases. Results: A total of 1957 consecutive urine cytology specimens were reviewed. Majority of the cases were negative for tumour (67.19%). The most common diagnostic category was acute inflammatory case (17.3%) while inconclusive cases constituted 11.39% of total. There were 23 (1.18%) positive cases that were diagnosed malignant on urine cytology. These 23 malignant cases were followed histologically and 22 (95.6%) cases turned out to be malignant. Conclusion: Urine cytological examination is an efficient tool that has a good diagnostic yield in detecting malignant urothelial lesions. It should be used routinely for diagnosing, screening and for follow-up of all malignant urothelial lesions.

Keywords: Urine cytology, urothelial neoplasm.

INTRODUCTION

The urinary tract is lined by transitional epithelium and historically this epithelium was so named by Friedrich Henle, a 19th century German pathologist, because he thought that the urinary epithelium was ‘transitional’ between squamous and glandular^1,2. It is now recognized as a specific type in its own right. Therefore, it is also called as ‘urothelium’. However, it is interesting that some tumours of the transitional epithelium do indeed express the ability to differentiate along squamous or glandular lines and that patches of squamous and glandular mucosa are commonly interspersed in benign transitional epithelium. Urine cytology is useful in diagnosing diseases that involve this mucosal surface and the urinary collecting system lined by transitional epithelium. There are three basic types of exfoliated urinary tract specimens: (1) voided urine, (2) catheterized urine, and (3) brushing/washing specimens. These specimens should be processed immediately or refrigerated and processed as soon as possible. If a delay is anticipated, immediate fixation with 50% ethanol may preserve the specimen for several days. In the cytology laboratory the ‘urinary fluid’ is treated as other body fluids and is centrifuged. The processed specimen is used to prepare smears.

Cytologic examination of a urine specimen is a simple, safe, and inexpensive method that may uncover a hidden urothelial cancer^1,2. Tumours of the urinary tract are relatively inaccessible to direct biopsy, and the tumours are often multifocal. Since the entire mucosal surface, including the farthest reaches of the urinary tract, is bathed in this easily obtained fluid, in theory, urine is the perfect specimen to examine for evidence of tumour. The well known indications for urine cytology examination are 1: for tumour detection and diagnosis of aggressive neoplasms or their follow-up, carcinoma in situ, small or inaccessible lesion as in ureters, pelvis, diverticuli etc.; 2: for screening of high-risk asymptomatic patients, as with industrial chemical or metal exposure, those with schistosomiasis or smokers etc.; 3: monitor tumours and therapy, for example low-grade non-invasive tumours, carcinoma in-situ². Cytology may become positive long before the cystoscopy or biopsy. But lesions cannot be anatomically localized with urine cytology alone.

This study is an attempt to review the practice of urine cytology examination in our setting of community hospital. The importance of urine cytology as a simple, safe, and inexpensive method for diagnosing and screening malignant lesions is also discussed.

MATERIAL AND METHODS

Our study sample consisted of 1957 consecutive urine cytology specimens examined at Department of Pathology at St. John Hospital and Medical Centre, Detroit. Cases during the time frame of one year from August 2001 to September 2002 were retrieved from laboratory archives. The cytological diagnosis were grouped in four categories according to WHO/ISUP (International Society of Uropathology 99)³; 1: negative, benign or reactive cases; 2: cases showing acute inflammatory changes; 3: inconclusive cases and 4: malignant cases. Only the positive malignant cases were followed with histological biopsy to determine the accuracy and efficiency of urine cytological examination for positive cases.

RESULTS

Majority of the cases were negative for tumour (67.19%). There were 35 cases (1.7%) that showed presence of RBCs, which could point to many lesions in the urinary tract. Twenty cases (1%) showed reactive urothelial cells only. The most common diagnostic category was acute inflammatory case (17.3%). Majority of the inflammatory cases showed acute inflammation with some reactive degenerated cells due to inflammation. Thirty-six cases showed candida hyphae with acute inflammation suggesting candida infection on cytology examination. Three cases showed trichomonas, 10 cases showed polyomavirus changes and 27 cases showed crystals with acute inflammation. Inconclusive cases constituted 11.39% of total. Majority of the cases were reported as atypical cells with significance unknown.

There were 23 (1.18%) positive cases that were diagnosed malignant on urine cytology. These 23 malignant cases were compared with histological biopsy and 22 (95.6% true-positive) cases turned out to be malignant and 1 case (false-positive) showed polyomavirus change on biopsy. Tables 1 to 4 summarize the four cytological categories with their age and gender distribution.

Table-1: Summary of benign urine cytological lesions with their gender and age distribution.

Cytological Diagnosis	Sex		Total	Age Range				Total	% of Total
	Male	Female		1-39	40-59	60-89	>90
Benign
No evidence of tumour	870	445	1315	139	492	675	9	1315	67.19
Blood in specimen	31	4	35	1	8	25	1	35	1.79
Reactive urothelial cells presents	18	2	20	—	5	15	—	20	1.02
Spermatozoa present	1	—	1	—	—	1	—	1	0.05
Subtotal Benign	920	451	1371	140	505	716	10	1371	70.06

Table-2: Summary of inflammatory urine cytological lesions with their gender and age distribution.

Cytological Diagnosis	Sex		Total	Age Range				Total	% of Total
	Male	Female		1-39	40-59	60-89	>90
Acute inflammation	109	60	169	7	43	113	6	169	8.64
Acute inflammation with reactive degenerated cells with bacteria	43	28	71	1	14	46	10	71	3.63
Acute inflammation with bacteria	13	11	24	3	7	14	—	24	1.23
Acute inflammation with bacteria and candida	3	2	5	—	2	3	—	5	0.26
Acute inflammation with candida	16	15	31	4	14	13	—	31	1.58
Acute inflammation with trichomonas	1	2	3	2	1	—	—	3	0.15
Atypical cells of Polyomavirus	7	3	10		3	7	—	10	0.51
Acute inflammation with Crystals	19	8	27	2	11	13	1	27	1.38
Subtotal Inflammation	211	129	340	19	95	209	17	340	17.37

Table-3: Summary of inconclusive urine cytological lesions with their gender and age distribution.

Cytological Diagnosis	Sex		Total	Age Range				Total	% of Total
	Male	Female		1-39	40-59	60-89	>90
Atypical cells favour reactive Inflammation	27	11	38	1	7	30	—	38	1.94
Atypical suspicious papillary low grade Carcinoma	7	5	12	1	4	7	—	12	0.61
Instrument reactive vs. low grade	20	3	23	3	4	16	—	23	1.18
Atypical squamous cells	3	3	6	1	3	2	—	6	0.31
Atypical significance unknown	97	12	109	4	20	83	2	109	5.57
Atypical cells suspicious for Carcinoma	29	6	35	1	6	28	—	35	1.79
Subtotal Inconclusive	183	40	223	11