1943 Gastrointestinal Plasmacytomas

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INTRODUCTION: Plasmacytomas are tumors consist of abnormal plasma cells.They are divided into solitary plasmacytomas of the bone and extramedullary plasmacytomas (EMP). GI tract involvement is seen in 7% of EMP cases. The small intestine is the most commonly involved GI site, followed by stomach, colon, and esophagus. CASE DESCRIPTION/METHODS: A 57-year-old African American female with a history of multiple myeloma treated with chemotherapy followed by autologous stem cell transplant with failure to achieve remission. She presented with a two day history of melena, hematochezia and fatigue. Vital signs: BP 85/45 mmHg, HR 98 bpm, T 98.6 F, RR 18, Oxygen sat 96% on RA. Labs showed a drop in hemoglobin from 8.4 g/dL to 4.9 g/dL. Upper endoscopy showed 1.5 cm polyp in the gastric body (Figure 1a) that was removed. Colonoscopy showed multiple colonic polyps with a 1.5 cm polyp (Figure 1b) in the ascending colon that was removed. Histopathologic examination of stomach polyp (Figure 2a,d) revealed a malignant neoplasm consisting of plasmacytoid cells with inconspicuous nucleoli and abundant mitotic activity. The neoplastic cells were directly infiltrating the residual gastric epithelium and extending beyond the muscularis mucosa. Immunohistochemical staining showed the cells to be strongly positive for CD138 and lambda light chain, while negative for CD20, CD3, and Kappa light chain. These findings were consistent with a diagnosis of plasmacytoma. Histopathologic examination of the colon polyp (Figure 2e,f) showed similar morphology to the gastric polyp. DISCUSSION: Gastrointestinal plasmacytomas are rare, accounting for approximately 7% of all EMPs. Endoscopically, GI plasmacytomas have variable morphological appearances including ulcers, polyposis, thickened folds, ulcerative masses, and constricting lesions. Differentiating GI plasmacytomas from other tumors require histopathological examination. GI plasmacytomas should be considered in the differential diagnosis of myeloma patients presenting with GI bleed.