Monoclonal Gammopathy Presenting with Pseudo Biclonal Pattern in Serum Protein Electrophoresis - An Interesting Perspective of Case Series.

INTRODUCTION: Monoclonal gammopathy (MG), arising from aberrant clonal proliferation of plasma cells, is diagnosed through the identification of an M-band via serum protein electrophoresis (SPEP), subsequently confirmed by immunofixation electrophoresis (IFE). The presence of two M-bands in SPEP is designated as double or biclonal gammopathy. Conversely, a pseudo-biclonal pattern is characterized by two M-bands on SPEP that resolve into a single immunoglobulin clone upon IFE. This case series delineates three instances of pseudo-biclonal patterns observed on SPEP in the absence of true biclonality.

METHODOLOGY: Following ethical approval, a retrospective analysis was conducted on SPEP reports from Sri Ramachandra Medical College & Research Institute, Chennai, spanning 2022 to 2024. Capillary electrophoresis was employed for SPEP, followed by immunofixation.

RESULTS: Three cases exhibiting pseudo-biclonal patterns were identified. Case 1 involved a 73-year-old male with acute kidney injury, hypercalcemia, osteopenia, multiple fractures, and a reversed albumin/globulin ratio, where a biclonal pattern on SPEP resolved to IgA Lambda on IFE. Case 2 concerned a 57-year-old male with nodal marginal lymphoma evaluated for myeloma, whose SPEP biclonal pattern resolved to IgM Kappa with elevated polyclonal immunoglobulins on IFE. Case 3 was an 86-year-old female with acute-on-chronic kidney disease and urosepsis, where SPEP showed a biclonal pattern resolving to IgG Lambda and an additional Lambda isomer on IFE.

CONCLUSION: This case series highlights pseudo-biclonal patterns stemming from monoclonal gammopathy, polyclonal elevations secondary to tumor lysis syndrome, and double gammopathy due to excess free light chains. The integration of SPEP with immunofixation, serum free light chain, and serum immunoglobulin assays enhances the detection of pseudo-biclonal patterns.