Extramedullary plasmacytoma mimicking colon carcinoma: an unusual presentation and review of the literature.

A 72-year-old woman presented to outpatient clinic with fatigue, light-headedness, dyspnoea and dark stool suggestive of lower gastrointestinal bleeding. She was previously diagnosed with multiple myeloma and completed 9 cycles of chemotherapy with bortezomib, lenalidomide and dexamethasone. She had very good partial response. A CT scan of the abdomen revealed a 9 cm mass at the hepatic flexure of the large intestine with an apple core deformity causing a marked narrowing of the lumen. Colonoscopy confirmed a large, nearly obstructing ulcerative mass in the distal right colon. The patient underwent a right hemicolectomy, distal ileal resection and lymph node dissection. Histopathology confirmed the mass as a plasmacytoma. Postoperatively, the patient was started with bortezomib and liposomal doxorubicin followed by carfilzomib. She showed excellent response to the chemotherapy.