Use of isoelectric focusing to discriminate transient oligoclonal bands from monoclonal protein in treated myeloma.

A 62-year-old diabetic man with prostate cancer first presented to our clinical laboratory in 2003 with a normal serum protein electrophoresis and immunofixation. In March 2009 he was diagnosed with an IgG κ myeloma. He underwent treatment and went into remission with the original paraprotein band being undetectable. Over the following 5 years, he developed oligoclonal bands and then eventually relapsed. Serum protein electrophoresis and immunofixation were inconclusive, however, isoelectrofocusing identified the oligoclonal pattern then the return of the original band, indicating relapse. This case illustrates the usefulness of an isoelectric focusing method to correctly determine clonality of small abnormal protein bands. It also highlights the need for appropriate commenting on reported results so that they are not confusing for clinicians.