[Primary malignant melanoma of the gallbladder. Case report and literature review].

An autopsy case of a 57-year-old man with primary melanoma of the gallbladder is described. The tumour appeared as a polypoid mass, measuring 4 cm in diameter. Microscopic examination revealed mostly spindle cells with vesicular nuclei and large nucleoli. Many cells stained positively for S 100 protein and HMB 45 using immunohistochemistry and they contained dark brown pigment that stained as melanin pigment with Fontana-Masson. The tumour had metastasised and affected the stomach, the duodenum, the jejunum, the lung, the brain and a bronchopulmonary lymph node. Examination of the skin and both eyes showed no abnormality. Primary malignant melanomas of the gallbladder are very rare. Only 23 cases have been described. These cases are summarized and reviewed.