Small cell carcinoma of the urinary bladder and prostate: Cytological analyses of four cases with emphasis on the usefulness of cytological examination

The occurrence of small cell carcinoma in the urinary bladder and prostate is rare. Only a few reports on the cytological features of small cell carcinoma of the urinary bladder in the urine specimen have been documented and, moreover, the urinary cytological features of prostate small cell carcinoma have been rarely reported. In this study, we analyzed the cytological features of four cases of small cell carcinoma of the urinary bladder and prostate, and discussed the usefulness of cytological examination of urine specimen for this type of tumor. This study included two urinary bladder and two prostate small cell carcinoma cases. Analyses of the cytological features of these cases revealed the following: i) the background was mostly inflammatory and necrotic material was also occasionally observed; ii) numerous tumor cells were present in two cases, whereas only a few neoplastic cells were observed in the remaining cases; iii) the neoplastic cells were small in size, had scant cytoplasm and a high nuclear/cytoplasmic ratio, and were arranged in small clusters or occasionally as single cells; iv) the tumor cell clusters showed prominent nuclear moldings; and v) the nuclei of the neoplastic cells were round to oval in shape with finely granular chromatin containing inconspicuous nucleoli. The cytological features of small cell carcinoma in the urine specimen are characteristic. Therefore, careful observation of the urine specimen may lead to a correct diagnosis of small cell carcinoma of the urinary bladder and, moreover, cytodiagnosis of prostate small cell carcinoma may also be possible.