Blood clonal B-cell excess in patients with monoclonal gammopathy of undetermined significance (MGUS): association with malignant transformation.
Fifty-seven patients with monoclonal gammopathy of undetermined significance (MGUS) were analysed for the presence of blood clonal B-cell excess (CBE), defined as a lymphocyte surface membrane kappa/lambda light chain ratio outside the normal range (> 3.5 in kappa-type MGUS and < 0.9 in lambda-type MGUS). 15 patients (26%) had a CBE. The patients were followed for a median time of 8.4 years (range 0.5-20.2). Eight of the 15 CBE+ MGUS patients (53%) developed a B-cell malignancy as compared to 7/42 patients (17%) in the CBE group and the difference in event-free (malignancy-free) observation time was statistically significant (P = 0.01). Cox's regression analysis showed that the presence of CBE was the most powerful predictor of progression to a malignant disease. Two patients with a normal kappa/lambda ratio at first test were analysed repeatedly during follow-up. Subsequently, a CBE appeared which gradually increased in size preceding the clinical diagnosis of a malignant disease.
Isaksson
E
E
Department of Oncology (Radiumhemmet), Karolinska Hospital, Stockholm, Sweden.
Björkholm
M
M
Holm
G
G
Johansson
B
B
Nilsson
B
B
Mellstedt
H
H
Osterborg
A
A
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001402:B-Lymphocytes / Q000276:immunology*; D002471:Cell Transformation, Neoplastic / Q000276:immunology*; D018450:Disease Progression; D005260:Female; D005455:Fluorescent Antibody Technique; D005500:Follow-Up Studies; D006801:Humans; D007145:Immunoglobulin kappa-Chains / Q000032:analysis; D007146:Immunoglobulin lambda-Chains / Q000032:analysis; D008297:Male; D008875:Middle Aged; D009101:Multiple Myeloma / Q000209:etiology; D014411:Neoplastic Stem Cells / Q000276:immunology*; D010265:Paraproteinemias / Q000150:complications / Q000276:immunology*; D011379:Prognosis; D012307:Risk Factors; D008258:Waldenstrom Macroglobulinemia / Q000209:etiology
D007145:Immunoglobulin kappa-Chains; D007146:Immunoglobulin lambda-Chains