Primary mucosal and glans penis melanomas: the Sydney Melanoma Unit experience

Melanomas that arise on mucosal surfaces and the glans penis are rare.

A retrospective study of the Sydney Melanoma Unit experience with 69 patients treated since 1956 for these types of melanomas was undertaken to determine primary lesion site, sex, age at diagnosis, symptoms, clinical stage at first presentation. histopathology, treatment and outcome.

Primary lesion sites were: nasal cavity (n = 9), oral cavity (n = 16), vulva/vagina (n = 25), anus/rectum (n = 13) and glans penis (n = 6). At diagnosis, 55 patients had local disease only, eight had regional lymph node metastases and six had widespread disease. Local recurrence as the first sign of relapse developed in 15 of the 55 stage I patients (three-stage system). Prognosis for the entire group was poor, only 10% being disease free 3 years after diagnosis and overall 3- and 5-year actuarial survival being 40% and 23%. respectively. The only statistically significant factor influencing survival was stage of disease at diagnosis (P = 0.002).

Possible reasons for poor survival include: (i) non-specific symptoms resulting in late presentation; (ii) locally advanced disease not being recognized by a clinician as a rare form of melanoma, resulting in a delay in treatment; (iii) anatomical constraints precluding surgery with generous margins and consequently resulting in a high incidence of local recurrence. Also, rich vascularity and multiple lymphatic drainage pathways may mean a predisposition to early dissemination. Prompt diagnosis and referral to a specialist unit for treatment and follow up are essential. Adequate surgery remains the cornerstone of treatment for these types of melanoma until more effective systemic therapies become available.