Melanoma of the Urinary Bladder: A Review of the Literature

Background. Melanomas of the urinary bladder and urethra are rare. Aims. To review the literature on the disease. Methods. Various Internet databases were used to identify reported cases of the disease. Results. Less than 30 cases of primary melanoma of the urinary bladder and urethra have been reported in the literature and they have been associated with melanosis and commonly with metastases. The lesions may be primary or metastatic with no gender preference. The diagnostic features include pigmented raised lesions which histologically exhibit spindled or epitheliod cells, necrosis, mitotic figures, and atypical melanocytes. Immunohistochemically they stain positively with S100; HMB45; and other melanocyte markers, but negatively with Keratin and Vimentin. The treatment involves excision and possibly IL-2. The prognostic factors include size and depth of invasion as well as metastatic lesions. Conclusions. Less than 30 cases (about 24 cases) of the disease have been reported. There are also reports of metastatic melanomas of the urinary bladder emanating from primary melanomas originating elsewhere. Diagnosis of the primary disease is based upon the histological appearance of the lesion, positive staining with S100 and HMB45, and evidence of absence of melanoma elsewhere. Primary melanoma of the bladder is usually a fatal lesion.