Primary biliary tract melanoma: Report of a case and review of the literature.

INTRODUCTION: Primary melanoma of the bile duct is extremely rare with only nine cases of primary melanoma of the bile duct reported in the literature. PRESENTATION OF CASE: A 55-year-old previously healthy gentleman developed increasing jaundice over several months and subsequently underwent an ERCP with stone extraction. Cytology brushings in an area of a distal stricture in the bile duct were concerning for cholangiocarcinoma. The patient was referred to our institution and underwent a pancreaticoduodenectomy. The surgical specimen showed a single 4.5cm polypoid lesion located in the bile duct. A diagnosis of melanoma was rendered after immunohistochemical studies on the tumor demonstrated positivity for melanoma markers. Follow-up of the patient with skin, ocular, and lymph node exams showed no evidence of melanoma. A PET scan 4 and 10 months post-surgery failed to reveal either a primary skin lesion or other sites of metastases. DISCUSSION: The vast majority of melanomas of the bile duct represent metastases from a cutaneous source and tend to present as multiple flat pigmented lesions. Conversely, cases of primary bile duct melanoma are characterized by a distinct gross morphology consisting of a solitary intraluminal polypoid lesion attached by a pedicle with no other identifiable primary lesion. Other supporting criteria include absence of other involved sites and presence of an in situ junctional component.
CONCLUSION: Given the clinical history, gross findings, and lack of a primary cutaneous site or other demonstrable metastases, this patient likely represents the tenth reported case of primary biliary tract melanoma.