Malignant melanoma in Meckel's diverticulum.

Meckel's diverticulum is a vestigial remnant of the omphalomesenteric duct, which is rarely affected by neoplasia. The authors report the first case of malignant melanoma in Meckel's diverticulum in a middle-aged man without skin or ocular lesions. Five other Meckel's diverticuli were evaluated histologically and by immunoperoxidase technics for neural crest elements, which could have given rise to this lesion.