PRIMARY MALIGNANT-MELANOMA OF THE BLADDER - IMMUNOHISTOCHEMICAL STUDY OF A NEW CASE AND REVIEW OF THE LITERATURE

Primary malignant melanoma of the genitourinary tract is an extremely rare lesion, comprising only 0.2% of all melanomas.(1) The urethra and penis are the most frequent sites of origin. Although melanoma metastatic to the bladder is quite common,(2) only 11 cases of primary malignant melanoma of the bladder have been reported to date.(3-11) We report a new case of primary malignant bladder melanoma in which immunohistochemical and autopsy studies were performed. The criteria introduced by Ainsworth to establish the bladder as the primary site were clearly observed in our case.(5) Immunohistochemical studies were done for vimentin, cytokeratin, HMB-45, neuron-specific enolase, S-100 protein, Leu-7, HLA-DR and proliferating cell nuclear antigen. We discuss histogenesis as well as the pathological criteria for and the use of immunohistochemical markers in the diagnosis of bladder melanoma as the primary site.