Extramedullary plasmacytoma (EMP) of urinary bladder.

An extramedullary plasmacytoma (EMP) is presented with an isolated lesion in the urinary bladder accompanying an IgG-K paraproteinemia. After a short-term oral melphalan administration, the tumor soon regressed together with the paraprotein, and has never recurred during the two-year follow-up. This is the fourth case of primary EMP of the urinary bladder reported in the literature.