Immunoglobulin D-λ/λ biclonal multiple myeloma: A case report

BACKGROUND Immunoglobulin D (IgD) multiple myeloma (MM) is a rare subtype of MM and commonly occurs in younger subjects but at a later stage of the International Staging System (ISS) when admitted. As a special type of IgD myeloma, IgD-lambda/lambda. biclonal MM is rarer. Its serum protein electrophoresis and serum immunofixation electrophoresis (IFE) might find no anomalies even if the bone marrow (BM) examination is performed. Thus, it is easy to miss the diagnosis. CASE SUMMARY A 62-year-old man diagnosed as IgD-lambda/lambda myeloma (ISS stage III) was admitted with fatigue and weight loss. The physical examination suggested an anemic face, a few moist rales at the left lung base, and mild concave edema in both lower extremities. Laboratory examinations showed the elevated creatinine levels, beta 2-microglobulin, lactic dehydrogenase, and erythrocyte sedimentation rate, while the decreased neutrophils, granulocytes, and hemoglobin. In the serum protein electrophoresis, there appeared two inconspicuous M-spikes. Serum IFE indicated an over-representation of lambda light chain and yielded two monoclonal bands in. region, but only one corresponding heavy chain band in the antisera to IgD region. The BM histology and BM cytology both supported the diagnosis of IgD lambda/lambda myeloma. CONCLUSION This case highlights the differential clinical manifestations and laboratory findings of IgD-lambda/lambda myeloma to help minimize the chance of misdiagnosis.