Metastatic Melanoma to the Common Bile Duct Presenting as Obstructive Jaundice: A Case Report and Literature Review

Abstract

Background: Metastatic melanoma involving the biliary tract is exceedingly rare and is often diagnosed at a late stage. Awareness of this entity is essential in patients with a prior history of melanoma who present with biliary symptoms. Case Presentation: A 35-year-old Caucasian woman with a history of cutaneous melanoma of the left chest and bilateral axillary and periclavicular nodal metastases, treated with wide local excision and lymphadenectomy 8 years earlier, presented with pruritus, malaise, dark urine, intermittent right upper quadrant pain, and jaundice. Laboratory evaluation demonstrated a cholestatic pattern, with marked hyperbilirubinaemia and elevated liver enzymes. Abdominal ultrasound revealed echogenic, non-shadowing material in a dilated common bile duct. Magnetic resonance cholangiopancreatography (MRCP) showed a 3 × 2 cm intraluminal mass in the common bile duct, with intrahepatic and extrahepatic biliary dilatation. Endoscopic retrograde cholangiopancreatography (ERCP) demonstrated a large, black-pigmented lesion in the common hepatic duct, which was biopsied, and a plastic stent was placed for decompression. Histological examination revealed pleomorphic epithelioid cells containing black-brown pigment. Immunohistochemistry showed strong positivity for SOX10 and Mart-1, with additional positivity for S100 and HMB-45, confirming metastatic melanoma. Biliary decompression led to symptomatic improvement, and the patient was referred for systemic staging and oncological management. Conclusion: This case highlights the diagnostic challenges of biliary tract involvement by metastatic melanoma and underscores the importance of maintaining a high index of suspicion in patients with a remote history of melanoma who present with obstructive jaundice. Multimodal imaging, endoscopic biopsy, and an appropriate immunohistochemical panel are critical for accurate diagnosis, and multidisciplinary management is required to optimise patient outcomes.