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An atypical finding on serum immunofixation: a case report
Ameerah Davids1,2, David F Keren3, Annalise E Zemlin1,2
1Division of Chemical Pathology, Department of Pathology, Faculty of Medicine and Health Sciences, Stellenbosch University, Cape Town, South Africa.
Laboratory Medicine
|October 9, 2025
Summary
This study details a rare case of oligosecretory multiple myeloma (MM) where standard tests for monoclonal proteins were inconclusive. The patient was diagnosed based on specific light chain findings and bone marrow examination, highlighting challenges in MM diagnosis.
Area of Science:
- Hematology
- Oncology
- Clinical Diagnostics
Background:
- Multiple myeloma (MM) involves abnormal plasma cell proliferation and monoclonal protein (M-protein) overproduction.
- Screening for MM typically involves serum protein electrophoresis, serum immunofixation (SIFE), and serum free light chain (SFLC) assays.
- M-protein migration in the alpha-2 region on electrophoresis is uncommon.
Purpose of the Study:
- To report a challenging case of suspected multiple myeloma with atypical M-protein findings.
- To investigate the diagnostic utility of advanced assays in oligosecretory MM.
- To highlight the management of a rare MM subtype.
Main Methods:
- Case presentation of a 55-year-old male with severe back pain and anemia.
- Utilized serum protein electrophoresis, SIFE, serum free light chain (SFLC) determination, bone marrow biopsy, and urine immunofixation.
- Employed mass spectrometry for SFLC analysis.
Main Results:
- Serum protein electrophoresis showed hypogammaglobulinemia; SIFE revealed unusual unrestricted kappa (κ) staining in the alpha-2 region.
- Markedly elevated κ SFLC and κ:λ ratio, with 90% plasmacytosis in bone marrow.
- Urine immunofixation showed a small κ restriction; mass spectrometry identified only polyclonal κ SFLC.
Conclusions:
- Absence of a clear M-protein on SIFE and discordant SFLC results complicated diagnosis.
- The patient was managed as oligosecretory multiple myeloma due to findings including bone marrow plasmacytosis and specific light chain patterns.
- This case underscores the importance of comprehensive testing in diagnosing rare MM presentations.
