Primary Malignant Melanoma of the Urethra

Abstract

The clinical and pathologic features of 15 primary urethral melanomas occurring 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 eight women it involved the distal urethra, usually the meatus; both the distal and proximal urethra were involved in one woman. The tumors were typically 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 nodular component in seven of them. A radial growth phase was seen in nine tumors. The depth of invasion ranged from 2 to 17 mm. The tumors had diffuse, nested, storiform, or mixed growth patterns. The neoplastic cells typically had abundant eosinophilic cytoplasm, large nuclei with prominent nucleoli, and brisk mitotic activity. Melanin pigment was seen in 12 tumors but was conspicuous 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, and 7 years. One patient died at the time of the initial operation, and one died of a ruptured aortic aneurysm at 3 years without evidence of melanoma at autopsy. Primary malignant melanomas of the urethra, one fifth of which are amelanotic, must be included in the differential diagnosis of a number of primary neoplasms that involve the urethra, including transitional cell carcinoma, sarcomatoid carcinoma, and sarcomas. Conventional prognostic factors, such as depth of invasion or tumor stage, do not seem to play as important a role in predicting survival as the mucosal location and the nodular growth present frequently in these tumors.

Primary Malignant Melanoma of the Female Urethra

“…Most cases are diagnosed after the fifth decade but some cases occur in younger patients [6,7]. The presenting symptoms include vaginal bleeding, mass, hematuria, and dysuria with a decreased urinary stream [8].…”

Melanoma of the female urethra

“…[7] Lesions can vary from millimetric up to 6 cm. [3] It has been described that up to 20% can be amelanotic, generating differential diagnosis such as transitional cell carcinoma or sarcoma,[38] pagetoid infiltrations of urothelial carcinomas[6] or even benign lesions.…”

“…[2] Very rarely it has been described in the proximal or middle thirds. [3] Metastasis from a primary cutaneous melanoma must always be excluded.…”

“…[2] It seems however, unlike cutaneous melanoma, prognostic factors such as depth of tumor invasion or tumor stage do not appear to have that much of an impact at predicting survival in mucosal localized melanoma, mostly because of its growth is usually nodular. [3]…”

“…[2] It is more frequent in women in a 3:2 ratio. [3] This location represents 0.2% of all melanomas. [4] The average age of presentation is 68 years,[2] ranging from 32 to 80 years of age.…”