Small cell carcinoma of the urinary bladder. Presentation of 23 cases and review of 134 published cases.

OBJECTIVE: To investigate the morphological diagnostic criteria and biology of the urinary bladder small cell carcinoma (SCC).

METHODS: Study of 23 cases of bladder SCC, looking for the clinical presentation, pathological features and evolution, and review of 134 previously published cases.

RESULTS: The SCC is infrequent (0.48-1%), 50% of them have areas of transitional cell carcinoma, supporting the metaplastic theory. The classic small cell morphology is the best diagnostic criterion. The neurone-specific enolase and chromogranin A are good markers, but not indispensable. An early metastatic incidence (56%) with a high mortality rate (68.7%), mostly before 2 years after the diagnosis, is the typical evolution. Only the patients with additional cis-platinum-based chemotherapy have better prognosis.

CONCLUSION: The pathologist should watch out for the presence of SCC and the urologist should consider the possibility of combined treatment for these cases.