S1801 Pancreatic Plasmacytoma Presenting as Jaundice in Patient With Relapsed Multiple Myeloma

Abstract

Introduction: Multiple myeloma (MM) is characterized by the neoplastic proliferation of plasma cells producing a monoclonal immunoglobulin. Extramedullary plasmacytomas (EP) are seen in 7% of patients with MM at the time of diagnosis, with an additional 6% developing as the disease progresses. The development of extramedullary disease (EMD) is associated with adverse prognosis and is difficult to treat. The most common sites of EMD include the chest wall, liver, lymph nodes, skin/soft tissue, and paraspinal area. EMD to the pancreas is among the most uncommon areas of involvement and is often diagnosed postmortem due to the indolent and generally asymptomatic progression. We present a 63-year-old female with relapsed MM manifesting as jaundice and biliary obstruction secondary to a pancreatic plasmacytoma. Her diagnosis was made using endoscopic ultrasound with fine-needle aspiration biopsy (EUS-FNA). Case Description/Methods: 63-year-old female with history of hypertension, anxiety, hypothyroidism, presented with back pain. Imaging showed widespread osteolytic lesions throughout the axial and appendicular skeleton. Lab workup revealed anemia, renal insufficiency, hypercalcemia, and a free kappa/lambda ratio of , 0.01. Bone marrow biopsy demonstrated sheets of large, atypical plasma cells compatible with MM. A repeat biopsy after 6 cycles of treatment showed 5-10% of residual plasma cells. An auto stem cell transplant was performed with minimal residual neoplasm on follow up. She presented again a few months later with rib pain. Imaging showed extensive multifocal osseous activity and a cutaneous plasmacytoma was found. Therapy was initiated, and she subsequently developed jaundice. Imaging demonstrated a 3.1x3.0cm lesion within the head of the pancreas, dilation of the intra and extrahepatic biliary ducts, and metastatic lesions involving the liver. EUS-FNA of liver and pancreatic lesions was performed and revealed malignant CD1381 cells with plasmablastic features (Figure). Discussion: The development of EMD in multiple myeloma is uncommon and associated with poor prognosis. The patient in our case developed multiple EPs including paraspinal, skin, liver, and pancreas. The pancreas is one of the least common areas of EMD development. It typically does not present until later in the disease course due to the indolent nature and is often diagnosed postmortem. Plasmacytoma can appear similar to other primary pancreatic diseases on imaging, which gives EUS-FNA an important diagnostic role.[1801] Figure 1. Endosonographic image of a fine-needle biopsy targeting a hypoechoic and well-defined lesion within the pancreatic head.