A Case of Extramedullary Plasmacytoma of the Small Intestine

Abstract

A 57-year-old man presented with diarrhea and vomiting. Abdominal radiography and computed tomography revealed small bowel obstruction with a small bowel tumor. Small-bowel endoscopy showed a stenosis completely encircled the jejunum, therefore laparotomy with partial resection of the small intestine was performed. The tumor was partly exposed through the serosa and grew circumferentially. Findings on pathological diagnosis showed tumor cells with the characteristics of plasmacytoma. Bone marrow biopsy indicated no evidence of plasma cell proliferation. No M-protein was found in the serum and urine. Therefore, multiple myeloma was ruled out and we diagnosed the case as extramedullary plasmacytoma. The common sites of extramedullary plasmacytoma are the nasal cavity, paranasal sinuses, gastrointestinal tract, lungs, thyroid gland, orbit, and lymph nodes. More than 80% of extramedullary plasmacytomas occur in the upper respiratory tract and oral cavity, and small bowel primary tumors are extremely rare. Nine cases of extramedullary plasmacytoma of the small intestine, including our case, were reported in Japan.