1351 The Peculiar Presentation of Extramedullary Plasmacytomas as Acute Pancreatitis

Abstract

INTRODUCTION: Extramedullary plasmacytomas (EMP) are a subcategory of plasma cell neoplasms that involve organs outside the bone marrow. Less than 5% of the cases are seen in the gastrointestinal tract. Pancreatic plasmacytomas are an extremely rare condition, with only 50-60 cases previously described in the literature. We report a unique case of concurrent gastric and pancreatic plasmacytomas presenting as acute pancreatitis. CASE DESCRIPTION/METHODS: A 62-year-old woman presented to the Emergency Department (ED) for epigastric pain radiating to back for one day. She had a history of multiple myeloma, which had relapsed after autologous stem cell transplant and progressed despite chemotherapy. On exam, she was jaundiced and had an elevated lipase to 1,112 U/L. A computed tomography scan of abdomen showed two masses involving the pancreatic head and body, with biliary and pancreatic duct dilatation. A subsequent endoscopic ultrasound revealed multiple nodules in the stomach. Biopsy of the gastric nodules and fine needle aspiration of the pancreatic lesions revealed atypical plasma cells with immunoreaction to kappa light chain, CD138, and CD56. These findings confirmed the diagnosis of extramedullary plasmacytoma. Acute pancreatitis and obstructive jaundice were diagnosed and an endoscopic retrograde cholangiopancreatography (ERCP) was performed. During the ERCP, a distal bile duct stricture was found and one metal stent was placed. Following the procedure, the patient reported gradual resolution of her abdominal pain and serum bilirubin returned to the normal range within one week. DISCUSSION: In previous reports, the majority of pancreatic plasmacytoma cases involved a single lesion located in pancreatic head which presented as painless, obstructive jaundice. We report a case of concurrent gastric and pancreatic plasmacytomas presenting with acute pancreatitis. It is important to recognize the extramedullary manifestations of multiple myeloma in patients presenting with acute pancreatitis and gastrointestinal tract lesions. This observation of aggressive tumor behavior in treatment-resistant multiple myeloma also suggests a potential modulation effect on the tumor and its microenvironment by chemotherapy and stem cell transplant. Further investigation into the underlying mechanism of metastasis in multiple myeloma may shed light on new therapeutic strategies to improve outcomes for future patients.