Mucous membrane melanoma C43.9

Malignant melanoma of the oral mucosa, nasopharynx, larynx, genital or ano-rectal mucosa (see below melanoma, malignant anorectal).

Rarely. In the USA incidences of 4/10 million inhabitants/year have been reported.

Occurring in adults, frequency peaks in the 5th-8th decade of life. No sex preference.

About 55% of mucosal melanomas affect the head and neck area, 24% the anorectal region and 21% the genital tract.

To date, no definitive clinical precursors of mucosal melanoma are known. Mostly it appears de novo as a bizarrely configured, initially brownish, later black spot on unchanged mucosa. The growth over years leads to an area growth and gradual thickness growth, so that a deep black, clearly palpable plaque can then be detected. In the advanced stage, a hemispherical, exophytic, deep black or black-red, bulging above the level of the mucous membrane, exophytic, deep black or black-red, bulging elastic nodule, which can reach up to 2 cm in diameter, appears. The surface is usually eroded or ulcerated at this stage, so that the tumour becomes symptomatic through bleeding. About 20% of oral mucosal melanomas are amelanotic, also desmoplastic or neurotropic melanomas. About 50% of oral mucosal melanomas have already metastasized to the regional lymph nodes at the time of initial diagnosis.

Surgical procedure with a stage-adapted safety distance (max. 2 cm) is the therapy of first choice. Post-irradiation seems to be of rather doubtful value regarding survival time, at least for melanomas of the head and neck mucosa. Radiotherapy is mainly used when R0 resection cannot be achieved due to the location and extent of the tumour.

In contrast to cutaneous malignant melanomas, c-Kit mutations are frequently (about 20%) detected in mucosal malignant melanomas. Several case reports are now available which show that c-kit mutants can be treated with c-kit blockers ( imatinib, sunitinib, dastinib) with extremely successful treatment results. Therefore, in case of metastasized mucosal melanoma with C-kit mutations, therapeutic approaches with c-kit blockers ( imatinib) are justified and reasonable.

Mucosal melanomas are usually discovered late, so that their prognosis is often worse than that of malignant melanomas of the skin due to advanced growth. The 5-year survival rate of all patients with mucosal melanomas is 25%, after the occurrence of lymph node metastases it drops to 17%.