Context: Nonsecretory plasma cell myeloma is characterized by an absence of detectable monoclonal protein in both the serum and urine. It is generally reported to comprise approximately 1% to 5% of all cases of plasma cell myeloma and, because of its rarity, requires a high index of suspicion and bone marrow biopsy to establish the diagnosis.
Objective: Review the diagnostic strategy when nonsecretory plasma cell myeloma is a clinical consideration in light of a relatively new serum free light chain assay.
Data sources: Case study and review of the literature.
Conclusions: Initial data using a recently developed nephelometric serum free light chain assay suggests that only about one fourth of nonsecretory plasma cell myeloma cases may be truly nonsecretory. The definition of nonsecretory plasma cell myeloma should be modified to exclude cases with evidence of clonality using the serum free light chain assay.