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Published on: January 17, 2018
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.
Introduction:
Multiple myeloma (MM) is characterized by the abnormal proliferation of plasma cells, resulting in the overproduction of distinctive monoclonal proteins (M-protein). Suspected MM necessitates screening for M-protein through a combination of serum protein electrophoresis, serum immunofixation (SIFE), and serum free light chain (SFLC) determination. An M-protein appears as a relatively restricted band on agarose gel, where migration in ɑ-2 is rare.
Methods:
A 55-year-old man with pulmonary tuberculosis presented with severe lower back pain. On examination, he appeared chronically ill, with conjunctival pallor. X-rays revealed vertebral compression fractures. The full blood count confirmed anemia; however, serum calcium and creatinine levels did not meet myeloma-defining event criteria.
Results:
The serum protein electrophoresis revealed hypogammaglobulinemia, with the SIFE demonstrating unusual unrestricted κ staining in the ɑ-2 region. A markedly elevated κ SFLC and κ:λ ratio were found. Bone marrow examination demonstrated approximately 90% plasmacytosis. Urine immunofixation revealed a small, restricted κ band disproportionate to the κ SFLC. Notably, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identified only polyclonal κ SFLC.
Discussion:
Given the absence of a discernible M-protein on SIFE, a small κ restriction on urine immunofixation, and a polyclonal increase in κ SFLCs, the patient's condition is being managed as an oligosecretory MM.
