Analysis of Multiple Bands on Serum Protein Immunofixation Electrophoresis: Challenge in Interpretation of Clonality in a Patient with Light Chain–Predominant Multiple Myeloma

Sera from patients with multiple myeloma usually display a single monoclonal immunoglobulin band on serum protein immunofixation electrophoresis. Multiple bands may be seen if the myeloma is bi- or triclonal or if the monoclonal immunoglobulin has rheumatoid factor activity. We describe a patient with light chain-predominant IgA lambda myeloma; the patient's serum displayed 2 spatially distinct bands reacting for alpha heavy and lambda light chains. The methods used to establish monoclonality are addressed.