An unusual urinary transitional tumor: the nested cell carcinoma. A case report with review of the literature

We report a case of nested cell carcinoma, an uncommon transitional tumor. These tumors are composed of regular cuboidal transitional cells forming sm all nests with minimal cytologic atypia. Despite the benign course, this tu mor resembling proliferation of Brunn's nests or inverted papilloma, must b e considered as an aggressive transitional tumor. Thus, morphologic criteri a are needed to make the diagnosis. Because of its aggressive behaviour, th e surgical therapy depends on the tumor's infiltration. (C) 2000 Editions s cientifiques et medicales Elsevier SAS.