Primary malignant melanoma of the common bile duct: An unexpected finding at pancreaticoduodenectomy: A case report.

Bile duct tumours are most commonly primary cholangiocarcinomas, and upfront surgical resection is often undertaken with curative intent, as preoperative histological confirmation is not routinely required. Melanoma, an aggressive malignancy of neural crest origin, can metastasize widely, but involvement of the biliary tract is exceedingly rare. Even rarer is primary melanoma of the bile duct. The present report describes a 44-year-old man presenting with obstructive jaundice and a mass in the common bile duct (CBD) presumed to represent cholangiocarcinoma. The patient underwent pancreaticoduodenectomy, but histopathology unexpectedly revealed malignant melanoma. Comprehensive staging and dermatological assessment excluded a cutaneous, mucosal or ocular primary, supporting the diagnosis of primary CBD melanoma. To the best of our knowledge, this represents the 14th reported case. This case highlights that melanoma, although rare, should be considered in the differential diagnosis of biliary obstruction, especially in younger patients, as it mandates a distinct postoperative oncological management pathway.