Malignant melanoma metastatic to the gallbladder. Case report and review of the literature.

A case of melanoma metastatic to the gallbladder is presented with review of the literature. Currently, there are 20 cases reported that have presented with acute and/or chronic cholecystitis. Ultrasonographic findings of an echogenic mass within the gallbladder without the accompanying acoustic shadowing can be diagnostic in a patient with a history of melanoma. The presence of tumor cells within the bile recovered from the common bile duct suggests the possibility of drop metastasis as a mechanism of spread to the common bile duct and the small intestine. The difficulties in distinguishing primary from secondary melanoma of the gallbladder are discussed.