Oral mucosal melanoma: some pathobiological considerations and an illustrative report of a case.

Oral mucosal melanoma is a relatively rare malignancy with an aggressive clinico-pathological behaviour. The mean 5-year survival rate is about 15 %. It arises primarily from melanocytes found in the basal cell layer of the epithelium, but may sometimes arise from melanocytes residing in the lamina propria. The pathogenesis is complex, and few of the molecular mechanisms underlying the development of oral mucosal melanoma have been defined. The extraneous risk factors associated with oral mucosal melanoma, if any, are unknown. Oral mucosal melanomas account for about 25 % of all mucosal melanomas of the head and neck, and exhibit a profile of cytogenetic alterations, and a pathobiological behaviour and clinical course different from that of cutaneous melanomas. As they are usually painless and grow quickly, as a rule, they are diagnosed late in the course of the disease when the lesions are already large and have metastasized to regional lymph nodes. In this paper we discuss some aspects of the pathobiology of oral mucosal melanoma, and present an illustrative case report.