S3575 A Unique Case of Acute Pancreatitis Due to Metastaic Melanoma to the Minor Papilla in a Patient With Pancreas Divisum

Abstract

INTRODUCTION: Metastatic melanoma can occur in the gastrointestinal tract in patients with diagnosed metastatic malignant melanoma. We present a case of metastatic melanoma to the duodenum and minor papilla in a patient with pancreas divisum, which served as a trigger for acute pancreatitis. CASE DESCRIPTION/METHODS: A 54 yr old male presented to the emergency department with severe abdominal pain, elevated lipase 1654 U/L (0–60) and mildly elevated liver function tests (AST 40 IU/L (14–30) ALT 55 IU/L (10–52)). CT scan showed a metastatic process involving the pancreas, liver, lungs, and also worsening pancreatic duct dilation (7 mm) compared to the previous CT scan three months prior. His past medical history was significant for melanoma of the right thumb s/p amputation, metastatic melanoma (BRAF V600E negative), tobacco abuse, and recent 20 pounds weight loss. Gastroenterology was consulted for acute pancreatitis and recommended an EUS and ERCP. EUS detected multiple hypoechoic round and oval masses within the pancreatic and liver parenchyma suggesting metastasis, and also pancreas divisum, with pancreatic duct measuring 5 mm in diameter. On ERCP, the major papilla and the main biliary duct were normal. However, on the endoscopic view, we detected many 3–10 mm black and flat infiltrative masses in the first and second portion of the duodenum, very suggestive of duodenal metastasis. One of the flat masses was found in the minor papilla. Subsequently the dorsal pancreatic duct was unable to be cannulated. Supportive care was recommended and he was discharged in stable medical condition. DISCUSSION: Metastatic melanoma metastasizes to the GI tract between 1-4% of patients with diagnosed metastatic malignant melanoma. Our patient had multiple metastasis visualized in the duodenum, a common site of tumor occurrence. The patient also had pancreatic divisum, previously undiagnosed and seen on EUS. These patients have a failure of the dorsal and ventral pancreatic buds fusing and thus result in majority of the pancreas draining through the dorsal duct of Santorini through the minor papilla. The abnormal fusion causes abnormal drainage of the majority of the pancreatic juice into the naturally narrowed minor papilla, causing elevation of intraductal pressure in some patients. Our patient had no prior episodes of pancreatitis prior to his metastatic melanoma diagnosis, making the melanotic lesion the likely culprit in this case for the occurrence of acute pancreatitis.Figure 1.: Minor Papilla with Metastatic Melanoma Lesion.Figure 2.: Multiple Metastatic Melanoma Lesions in Duodenum.Figure 3.: Normal Major Papilla.