[Anaplastic tumor of the bladder with neurosecretory granules and benign courses]

We report on a 59-year-old female patient with a bladder tumor that was initially classified as anaplastic (undifferentiated) tumor. Posteriorly, electron microscopic and immunohistochemical analyses of the specimen revealed a neuroendocrine tumor distinct from a paraganglioma. The origin and prognosis of bladder carcinoids and small cell undifferentiated carcinomas are discussed. The authors indicate that the level of bladder wall infiltration is the most important prognostic parameter in these type of tumors.