Microcystic transitional cell carcinoma: a rare tumor of the urinary bladder.

Microcystic urothelial carcinoma is a rare variant of invasive transitional cell carcinoma recognized by the WHO classification. It is characterized by its deceptively benign appearance. The clinical course of this uncommon variety of carcinoma is not well known and their histological and immunohistological features are not well defined. We report a case of a 37-year-old man with a microcystic transitional cell carcinoma of the urinary bladder. He was diagnosed 4 years ago with cystitis glandularis lesions and nephrogenic adenoma. Through this observation we will try to define the clinical and pathological features of this uncommon tumor which must be differentiated from a number of proliferative lesions of the urothelium. The poor prognosis and aggressiveness of this tumor seems to be related to a higher stage and grade at diagnosis.