Pancreatic Plasmacytoma Presenting as Acute Pancreatitis: An Unusual Extramedullary Onset of Multiple Myeloma

Multiple myeloma (MM) typically manifests with bone pain, anemia, and hypercalcemia. Extramedullary disease (EMD), particularly pancreatic involvement, is rare. We report a 63-year-old woman presenting with acute pancreatitis secondary to a pancreatic plasmacytoma. Initial symptoms included epigastric pain, elevated lipase (1,389 U/L), and imaging revealing a 12.1 cm pancreatic mass. Biopsy confirmed lambda-restricted plasma cells (CD138+). Bone marrow biopsy showed 15% clonal plasma cells, meeting the diagnostic criteria for MM. EMD in MM signifies aggressive disease and poor prognosis.