Undifferentiated small-cell carcinoma of the urinary bladder: report of two cases with a primary urinary cytodiagnosis.

Two undifferentiated small-cell carcinomas of the urinary bladder are reported. The patients, 68- and 55-yr-old men, respectively, presented with painless hematuria. In the first case, numerous small, lymphocyte-like cells with coarse chromatin, sometimes with small nucleoli, and high nuclear/cytoplasmatic ratios were found in cytologic urine specimens. A cytodiagnosis of undifferentiated small-cell cancer was made. In the second case, urine samples showed rare aggregates of small, undifferentiated cells in association with malignant urothelial cells. The cytodiagnosis of mixed tumor composed of undifferentiated small cell and transitional carcinoma was confirmed by histologic examination. The presence of focal reactivity with anti-chromogranin antibody and neurosecretory granules via electron microscopy supports a neuroendocrine differentiation for the small neoplastic cells. The patients died 13 and 8 mo after diagnosis, respectively.