ABSTRACT
Plasmacytoma in patients with multiple myeloma usually develops in the advanced stage of the disease. We report herein an atypical case of extramedullary relapse of multiple myeloma that presented as mechanical obstruction of the small bowel in a patient who had achieved complete remission after chemotherapy. A 75-year-old man was diagnosed with multiple myeloma 25 months previously and treated with a bortezomib-containing chemotherapy regimen. He presented for evaluation of abdominal pain. A circumferential mass resulting in mechanical ileus was observed by abdominal computed tomography. Biopsy after surgical resection confirmed the diagnosis of plasmacytoma. The patient was subsequently treated with thalidomide-containing chemotherapy, but he died of disease progression after 6 months. We suggest careful observation of unusual relapses of multiple myeloma in patients who have achieved complete remission after antimyeloma therapy.