Urethral involvement is associated with higher mortality and local recurrence in vulvar melanoma: a single institutional experience

Abstract

Vulvar malignant melanoma (VMM), although uncommon, comprises 5-10% of all vulvar malignancies. Local control is notoriously poor in VMM with recurrence rates of 30-50% compared with approximately 3% in cutaneous melanomas. We studied clinicopathologic features of 37 women with VMM, after reviewing three decades of clinical follow-up data in our institutional databases. Most patients were Caucasian (n=35) with an average age at diagnosis of 60.6 years (range 23-83). The most common subtype was mucosal lentiginous melanoma (n=25). We compared Kaplan-Meier survival curves of 31 patients defined by clinical and microscopic attributes using exact log-rank tests. Younger patients at diagnosis (23-64 years), those with thin melanomas (≤1mm), and those with Clark's level II or III tumors had better 5-year survival rates than older patients (65-83 years)and those with thick melanomas (>1mm) and those with Clark's level IV or V (P≤0.05), respectively, by exact log-rank test. Local recurrence of melanoma occurred in 15 patients. Nine patients (24%) had eventual urethral involvement by malignant melanoma, and this feature was associated with significantly shorter survival (P=0.036). Patients with urethral involvement had shorter median time to death and worse 5-year survival rates. Given that spread to the urethra is common in VMM and urethral recurrence is also associated with mortality, pathology excision specimens should be carefully reviewed with attention to urethral involvement as a potentially important prognostic factor.