Multiple myeloma arising from solitary plasmacytoma of bone.

Double (kappa + lambda), Bence Jones (BJ) proteinuria was detected in a male patient of 73 years. The disease started as a solitary plasmacytoma in bone and transformed into multiple myeloma. At the beginning, isolated BJ lambda proteinuria was observed which was soon accompanied by transient excretion of BJ kappa protein.