Primary and Secondary Malignant Melanoma, and Other Melanotic Tumor, of the Hepatobiliary Tract

Abstract

Malignant melanoma (MM) is an aggressive malignancy that frequently involves the hepatobiliary tract, due to the frequent metastases to the liver. Therefore, most of malignant melanotic lesions detected in the liver and bile ducts are metastases of skin melanomas. But there is a small group of MM that takes its origin in the hepatobiliary tract, albeit the cell of origin is not yet known, possibly a neural crest cell that homed to this organ during embryogenesis. Primary MM is well documented for extrahepatic bile ducts and the gallbladder, where primary MMs have been described since long. In particular, primary gallbladder MM is a recognized entity with characteristic growth patterns. In contrast, primary hepatic MM is less well defined and numerous cases published in the old literature may be misinterpretations because metastatic disease is difficult to exclude in many cases, because the primary tumor may have been missed or had regressed. A distinct situation is ocular MM which is known to produce liver metastases after a long time delay. There are rare other melanotic tumors that can manifest in the liver, including melanotic progonoma. A tumor related to MM and known to have visceral manifestations is clear cell sarcoma or melanoma of soft parts.