S2946 Extramedullary Multiple Myeloma Affecting the Gastrointestinal Tract, a Case Report

Abstract

INTRODUCTION: Multiple myeloma (MM) is a neoplastic proliferation of plasma cells that accounts for 1 to 2% of all cancers. Symptoms are classically related to plasma cell infiltration into the bone marrow and overproduction of immunoglobulins. Rarely, this hematological malignancy can manifest outside of the marrow, and GI tract involvement is seen in as little as 0.9% (1). Here, we present a case of a previously undiagnosed multiple myeloma presenting as abdominal pain with gastrointestinal plasmacytomas. CASE DESCRIPTION/METHODS: A 41-year-old female with past medical history of uncontrolled diabetes presented to the emergency department for diffuse abdominal pain. On presentation, labs were notable for lipase greater than 6000 U/L, Hgb of 7 g/dL and Plt of 18,000/uL. An abdominal CT scan showed gastric wall thickening, and the patient was admitted for acute pancreatitis. An upper endoscopy was performed for acute decline in hgb (5.5 g/dL) with concern for a bleeding peptic ulcer. Endoscopy revealed a 5mm lesion in the middle third of the esophagus, multiple 4–30mm semi-sessile polyps in the stomach with stigmata of recent bleeding, and multiple similar polyps in the duodenum. Biopsies were obtained as the lesions were not amenable to endotherapy. A bone marrow biopsy was then performed and suspicions for malignancy were confirmed when pathology showed sheets of plasma cells virtually replacing all marrow, consistent with multiple myeloma. Endoscopic biopsy results of the lesions revealed plasma cells forming plasmacytomas in the setting of MM. The patient’s hospital course was complicated by further gastrointestinal bleeding, bacteremia and malignant central nervous system involvement. Due to poor prognosis and clinical decline, the patient’s family opted for home hospice care. DISCUSSION: Multiple myeloma is a hematological malignancy that can progress rapidly. Symptoms are primarily related to overproduction of immunoglobulins from neoplastic plasma cells and marrow infiltration, but rarely, MM can manifest as extramedullary disease. Gastrointestinal involvement is particularly rare and carries an unfavorable prognosis. Our case demonstrates the poor clinical outcomes associated with the uncommon presentation of MM in the gastrointestinal system.Figure 1.: Plasmacytomas.