[Report of a new case of small cell carcinoma of the oat-cell type in the bladder and review of the literature].

We report an additional case of small cell carcinoma of the bladder with oat cell features in a 67-year-old male patient. This tumor, recently described at this site, has clinico-pathological features that make it distinct from other bladder tumors. Histologically, it closely resembles its pulmonary counterpart with positive results for epithelial markers and neuroendocrine differentiation. The latter has been confirmed by the observation of the typical neurosecretory granules at ultrastructural level. It generally presents in the elderly male patients. It is extremely aggressive and responds poorly to the commonly used treatment. The histogenesis of this rare tumor of the bladder has, as yet, not been elucidated. The different hypotheses that have been put forward are discussed.