Malignant melanoma of the gallbladder. Report of a case.

A case of malignant melanoma in a 31-year-old man is described to add to the eight cases previously reported in the literature. The tumor in this case shares many common gross and microscopic features with those previously reported. These similarities, in addition to the clinical absence of any primary melanoma in the more common site of occurrence, indicate that the tumor in this case is primary in the gallbladder.