Prostatic cancer presenting monoclonal gammopathy: report of two cases.

Two cases of prostatic cancer accompanied by monoclonal gammopathy of undetermined significance (MGUS) are reported. Both cases presented IgG-lambda type hyperimmunoglobulinemia and Bence Jones protein (BJP) in the urine. A characteristic of both cases was significant multiple bone metastasis, and one case also demonstrated a severe immunological disorder. During the treatment, one patient recovered from MGUS. We recommend that elderly male patients manifesting MGUS be examined for prostatic cancer.