S1913 A Rare Case of Spindle Cell Carcinoma of the Hepatobiliary System

Abstract

Case Description/Methods: An 84-year-old male presented with epigastric abdominal pain. 3-years prior he had wide local excision for cutaneous malignant melanoma of the upper back (R0 resection). His abdominal pain had worsened over the last 4-weeks and was preceded by jaundice and unintentional weight loss. Initial studies were significant for elevated alkaline phosphatase (1295), AST (270) ALT (212), total bilirubin (10.1) and lipase (12085). Computed tomography (CT) showed a 2.4 cm lesion in the pancreatic head along with dilated pancreatic duct and biliary dilation. Carbohydrate antigen 19-9 (CA19-9) was elevated (628). Cholangiogram showed a 15 mm distal biliary stricture with upstream dilation. Brushings of the biliary stricture were unsatisfactory due to insufficient cells. Subsequent endoscopic ultrasound (EUS) demonstrated a 25mm by 25mm mass in the pancreatic head invading the distal CBD. Fine-needle aspiration (FNA) showed a poorly differentiated malignancy with epithelioid and focal spindle cell features with positive S100 and SOX-10 immunophenotype. Findings consistent with melanoma. Additional imaging did not reveal other potential sites of metastasis. The patient has since been discharged and is undergoing further evaluation. Discussion: Approximately one-third of patients with malignant melanoma develop metastases. However, metastatic melanoma of the gastrointestinal system is only seen in 2-4% of patients affected by cutaneous melanoma. This patient had a unique presentation with invasion of his pancreatic lesion into the distal common bile duct which lead to obstructive jaundice and pancreatitis. Pancreatitis as a result of metastatic melanoma is a rare presentation only described in a few case reports. Based on imaging it appears the patient initially had isolated metastatic disease of the pancreas which then invaded into the common bile duct. Isolated pancreatic metastasis represents less than 1% of all metastatic melanomas. It is difficult to differentiate a primary cancer from metastatic disease of the pancreas based on imaging alone. The use of EUS-FNA is essential for diagnosis. Though the exact prognosis of metastatic melanoma of the pancreas is unclear, generally metastatic melanoma carries a poor prognosis.