Extramedullary plasmacytoma of the colon: a case report.

Extramedullary plasmacytoma is a rare cause of nonobstructive colonic masses, which is often disregarded. Plasmacytoma is a neoplastic proliferation of plasma cells; when systemic involvement occurs, the disease is named multiple myeloma. Extramedullary plasmacytomas comprise 4% of all plasma cell tumours and occur mainly in the upper respiratory tract; gastrointestinal system involvement is rare. In this case we describe a rare cause of gastrointestinal system mass: extramedullary plasmacytoma involving the left colon.