The clinical spectrum of pure Bence Jones proteinuria. A study of 66 patients

Sixty-six consecutive patients exhibiting isolated urinary excretion of monoclonal free light chains, i.e. Bence Jones protein (BJP), on screening investigation for serum and urine monoclonal immunoglobulins were studied in order to better define the spectrum of immunoproliferative disorders associated with such a protein abnormality. The typical plasma cell neoplasms accounted for only one third of the cases, multiple myeloma (MM) and systemic amyloidosis (AL) being diagnosed in 18% and 15% of the patients, respectively. Eighteen (27%) of the patients were recognized as having malignant nonHodgkin's lymphomas (NHL), 21 (32%) had chronic lymphocytic leukemia (CLL), and 2 (3%) had hairy cell leukemia (HCL). Three patients (5%) without apparent evidence of any malignant immunoproliferative disease were classified as having a monoclonal gammopathy of undetermined significance (MGUS). The greatest urinary concentrations of BJP were found in plasmacytic neoplasms, the daily excretion of MM patients being significantly higher than that of AL patients. Considerably lower BJP outputs were recorded in the other diseases, the lowest ones being associated with MGUS. NHL patients had a daily excretion four times higher as compared with that of CLL patients. The distribution of NHL by histologic type was: follicular center cell lymphomas (FCCL) 39%, small lymphocytic lymphoma (SLL) 33%, immunoblastic lymphoma (IBL) 17%, and plasmacytoid lymphocytic lymphoma (PLL) 11%. The highest BJP levels were found in PLL, and the lowest ones in FCCL. In CLL patients the amount of urinary BJP correlated significantly with the tumor load, as estimated by the number of enlarged lymphoid areas. The study suggests that detection and measurement of isolated urinary BJP may provide useful data for the clinical evaluation of a wide spectrum of immunoproliferative disorders.