A Rare Presentation of Extramedullary Plasmacytoma: A Case Report

Introduction: Extramedullary plasmacytoma is a rare manifestation of monoclonal plasma cell disorders, typically involving the upper aerodigestive tract. Gastrointestinal involvement is uncommon, and synchronous lesions in separate GI sites are particularly rare. Case Report: A 58-year-old male was referred to the Gastroenterology department following the incidental identification of two subepithelial lesions, measuring 10 mm and 15 mm in the transverse and descending colon, respectively, during routine screening colonoscopy. A subsequent hospital-based colonoscopy confirmed these lesions and revealed additional nodular subepithelial lesions in the terminal ileum. Endoscopic biopsies were inconclusive. One colonic and one ileal lesion were removed via endoscopic mucosal resection. Histopathological and immunohistochemical analysis confirmed IgG-kappa extramedullary plasmacytomas. Further hematological evaluation revealed no cytopenias, renal dysfunction, or hypercalcemia. Skeletal survey was unremarkable, and bone marrow biopsy showed phenotypically normal plasma cells. Given the multifocal gastrointestinal involvement, systemic therapy with bortezomib, dexamethasone, and lenalidomide was initiated, and the patient was referred for autologous stem cell transplantation. Conclusion: This case involves a rare entity with an exceptionally uncommon presentation – multifocal gastrointestinal plasmacytomas – posing unique diagnostic and therapeutic challenges that require a multidisciplinary approach. Early recognition is crucial, given the risk of progression to multiple myeloma and the need for timely, effective intervention.