Excessive Immunoglobulin Lambda (λ) Light Chain Production with Thrombocytopenia and Anaemia in a Patient with Smoldering Multiple Myeloma: A Case Report

Abstract

Smoldering Multiple Myeloma (SMM) is defined as focal premalignant plasma cell proliferation in the bone marrow, along with the presence of monoclonal or biclonal protein bands in the patient’s serum. The current patient complained of severe weakness six months after knee arthroplasty. The patient exhibited a monoclonal (M-1) band on Serum Protein Electrophoresis (SPEP), which was observed in the γ-globulin region in combination with γ-heavy chains. Another protein band (M-2) was identified in the β-globulin region. These paraproteins were later confirmed by Immunofixation Electrophoresis (IFE), and both proteins reacted with anti-λ antibody. The concentration of the M-1 band was 32% (2.82 gm/dL), while the concentration of the M-2 protein band was 7.9% (0.7 gm/dL). Additionally, the total serum proteins measured 8.84 gm/dL. The plasma cell count in the Bone Marrow (BMPC) was approximately 20%. Provisionally, the patient was diagnosed as a case of gammopathy, with non-IgM Monoclonal Gammopathy of Undetermined Significance (MGUS), light chain MGUS, SMM, and MM considered in the differential diagnosis. However, the final diagnosis for the current patient was SMM. The patient responded well to treatment with cyclophosphamide and prednisone.