Primary malignant melanoma of the urethra - A clinicopathologic analysis of 15 cases

The clinical and pathologic features of 15 primary urethral melanomas occur ring in patients (nine women and six men) age 44 to 96 years (mean age, 73 yrs) are described. In the men the tumor involved the distal urethra. In ei ght women it involved the distal urethra, usually the meatus; both the dist al and proximal urethra were involved in one woman. The tumors were typical ly polypoid and ranged from 0.8 to 6 cm (mean, 2.6 cm) in maximum dimension . A vertical growth phase was present in all tumors, with a prominent nodul ar component in seven of them. A radial growth phase was seen in nine tumor s. The depth of invasion ranged from 2 to 17 mm. The tumors had diffuse, ne sted, storiform, or mixed growth patterns. The neoplastic cells typically h ad abundant eosinophilic cytoplasm, large nuclei with prominent nucleoli, a nd brisk mitotic activity. Melanin pigment was seen in 12 tumors but was co nspicuous in only six. At the time of diagnosis, 13 tumors were confined to the urethra and two patients had lymph node metastasis. Nine patients died of disease 13 to 56 months after initial diagnosis and treatment, and one patient had a local recurrence at 4 years and subsequently died of sepsis 1 year later. Three patients were alive and well at 11 months, 23 months, an d 7 years. One patient died at the time of the initial operation, and one d ied of a ruptured aortic aneurysm at 3 years without evidence of melanoma a t autopsy. Primary malignant melanomas of the urethra, one fifth of which a re amelanotic, must he included in the differential diagnosis of a number o f primary neoplasms that involve the urethra, including transitional cell c arcinoma, sarcomatoid carcinoma, and sarcomas. Conventional prognostic fact ors, such as depth of invasion or tumor stage, do not seem to play as impor tant a role in predicting survival as the mucosal location and the nodular growth present frequently in these tumors.