Primary and metastatic diseases in malignant melanoma of the gastrointestinal tract.

In this review, the gastrointestinal (GI) manifestations of malignant melanoma including primary mucosal melanoma of the GI tract and metastatic melanoma to the GI tract are discussed. Although malignant melanoma most commonly arises in the skin, primary melanomas can also arise from the mucosal epithelial lining of the gastrointestinal tract. The vast majority of gastrointestinal melanoma is metastatic from a cutaneous primary; however, there is evidence that melanoma can arise de novo from within certain areas of the gastrointestinal system. The sporadic nature and small numbers of patients reported in the literature with mucosal melanomas have prevented a good understanding of the pathogenesis, natural history, and optimal treatment of this uncommon presentation of melanoma.