Primary malignant melanoma of the mucous membranes

To investigate malignant mucosal melanoma (MMM), a rare disease and one which has, till lately, remained unrecognized. Incidence of MMM ranges from 2 to 10% in various series.

We retrospectively reviewed the cases of malignant melanoma treated at the Regional Cancer Centre, Trivandrum, India, over a period of 15 years.

A total of 163 cases of melanoma were identified, of which 21 had a lesion in mucosal sites. There were eight cases of upper aero-digestive tract (UADT) melanoma, seven cases of rectal melanoma, five cases with lesions in the vagina and one case with a lesion in the urethra. The mean age of the patients was 52.8 years; mean age of presentation in urogenital and anorectal lesions was similar to overall mean age, while this was lower (47.5 years) for UADT lesions. Almost half of the patients presented with ulcer or nodule with or without pigmentation. Pain was present in three-quarters and vaginal bleeding was present in all cases of vaginal lesions. Almost one-third of the patients failed locally while another third developed distant metastasis during the follow-up period. A 2-year disease-free survival rate of 13.2% (95% CI: 2.2-34.1) was observed, which dropped to 6.6% (95% CI: 0.4-25.7) after 3 years. Survival appeared a little better in UADT melanoma compared to urogenital and anorectal melanoma; however, the difference was not statistically significant.

Malignant mucosal melanoma seems to have an aggressive biological behaviour with a high incidence of local failure and metastasis.