Urine cytology of nonurothelial malignancies-a 10-year experience in a large multihospital healthcare system.

BACKGROUND: Urine cytology is the most frequently utilized test to detect urothelial cancer. Secondary bladder neoplasms need to be recognized as this impacts patient management. We report our experience on nonurothelial malignancies (NUM) detected in urine cytology over a 10-year period. METHODS: A 10-year retrospective search for patients with biopsy-proven NUM to the urothelial tract yielded 25 urine samples from 14 patients. Two cytopathologists blinded to the original cytology diagnosis reviewed the cytology and histology slides. The incidence, cytomorphologic features, diagnostic accuracy, factors influencing the diagnostic accuracy, and clinical impact of the cytology result were studied. RESULTS: The incidence of NUM was <1%. The male:female ratio was 1.3. An abnormality was detected in 60% of the cases; however, in only 4% of the cases, a primary site was identified accurately. Of the false negatives, 96% was deemed as sampling errors and 4% was interpretational. Patient management was not impacted in any of the false-negative cases due to concurrent or past tissue diagnosis. CONCLUSION: Colon cancer was the most frequent secondary tumor. Sampling error attributed to the false-negative results. Necrosis and dirty background was often associated with metastatic lesions from colon. Obtaining history of a primary tumor elsewhere was a key factor in diagnosis of a metastatic lesion. Hematopoietic malignancies remain to be a diagnostic challenge. Cytospin preparations were superior for evaluating nuclear detail and background material as opposed to monolayer (Thinprep) technology. Diagnostic accuracy was improved by obtaining immunohistochemistry. Diagn. Cytopathol. 2016. © 2016 Wiley Periodicals, Inc. Diagn. Cytopathol. 2017;45:22-28. © 2016 Wiley Periodicals, Inc.