Small cell carcinoma arising from the proximal urethra.

Primary neuroendocrine carcinomas of the lower urinary tract are distinctly rare, locally aggressive neoplasms with a high rate of metastasis. We present a case of primary small cell carcinoma of the urethra occurring in a 64-year-old man. The clinical, histological and immunohistochemical features of urethral small cell carcinoma are highlighted with respect to the differential diagnosis of neuroendocrine and other urethral tumors. The possible histogenesis of urethral small cell carcinoma, reported at this location in only a small number of cases, is briefly discussed. We favor an origin from pluripotent epithelial stem cells as one of the possible histogenic pathways.