Primary melanoma of the mucous membranes is a rare subtype of melanoma that arises in melanin-producing cells in the body’s mucous membranes. This type of melanoma represents about 1% of all cases of melanoma, but mainly affects the oral cavity (10% of cases) of black patients and represents about 4% of all melanomas.
Unrelated to exposure to the sun or other forms of ultraviolet radiation, it can develop anywhere on the body that contains mucous tissue, but it prefers the male sex with a male:female ratio of 1.7:1. Initially it appears as a blackish-brown patch with irregular borders that rapidly spreads to the periphery, and ulcerations may appear over time.
The most common localizations include the oral cavity, in particular the hard palate, but also the genital mucosa (10% of cases the vulva and 2% the vagina), the conjunctiva, rarely the rectum (3%) and the nasopharynx. The prognosis is severe as for all melanomas of the cephalic tract, and can be inauspicious even after destructive therapy in case of involvement of the genital mucous membranes.
Diagnosis may be delayed due to the internal location of the tumor, and often occurs due to the presence of symptoms such as oral pain, pain with intercourse, tenesmus, pruritus, or rash. Although dermatoscopy helps less than in skin melanomas, an atypical vascular pattern can sometimes be identified that can help plan an excision or incisional biopsy.
Treatment decisions, which may include surgery, radiation therapy, chemotherapy, targeted therapies, and immunotherapy, depend on the location of the tumor, the stage of the melanoma, the patient’s age, and general health.