Clinical Chemistry - Case Study
Student Discussion Document (pdf)
Jack L. Wu, Maria Alice V. Willrich, Mark Martinez, Theodore W. Kurtz, and Xander M.R. van Wijk
A 64-year-old male presented with weight loss, fatigue, and abdominal pain. Imaging demonstrated multifocal abdominal and retroperitoneal lymphadenopathy. Laboratory evaluation revealed significant leukocytosis (>50–60 × 109/L), a substantial creatinine elevation (3.3 mg/dL) and reduced estimated glomerular filtration rate (eGFR) (20 mL/min/1.73 m2), two low-level monoclonal (M)-protein spikes (0.4 and 0.2 g/dL) on SPEP, and markedly elevated λ free light chains (FLCs; λ >11 000 mg/L, κ 5 mg/L, and κ/λ <0.01) for which the patient received plasma exchange. Peripheral blood smear and flow cytometry identified approximately 80% of circulating leukocytes as plasma cells. Bone marrow biopsy demonstrated 95% hypercellularity with atypical anaplastic cells and high-grade cytologic features. A retroperitoneal core biopsy revealed an aggressive plasmacytoid neoplasm with plasmablastic features, consistent with PCL involving extramedullary sites.
IFE showed one band in the λ lane, in contrast to SPEP, which had shown the 2 low-level M-protein spikes in the gamma region (both SPEP and IFE were performed using Helena SPIFE 4000). In addition, analysis of M-proteins by mass spectrometry using MASS-FIX identified a single monoclonal λ light chain of 22 782 Da without detection of a corresponding heavy chain.