Anorectal involvement in a patient with multiple myeloma.

Multiple myeloma is a neoplastic proliferation of monoclonal plasma cells. Symptomatic gastrointestinal involvement is uncommon. We report the case of a 45-year-old patient admitted with an anorectal polypoid lesion, which progressed to colonic obstruction. Investigation revealed a secondary plasmacytoma associated with multiple myeloma. We discuss the characteristics of this rare entity with poor prognosis, its clinical implications and treatment options.