ABSTRACT
BACKGROUND: Multiple myeloma (MM) accounts for approximately 10% of hematological malignancies. The monoclonal immunoglobulin G kappa (IgG-κ) daratumumab can bind to CD38 on MM cells and be detected in serum immunofixation (IF), causing pitfalls in M-protein quantification. OBJECTIVES: To determine the efficacy of mitigating the interference of IgG MM treated with daratumumab. METHODS: Levels of Ig, free light chains (FLC) kappa (κ) and lambda (λ), serum protein electrophoresis (SPE)/IF, and Hydrashift 2/4 assays were assessed following manufacturer's instructions in three patients. RESULTS: Patient 1 was a 70-year-old male diagnosed with IgG-λ MM. The IF distinguished two monoclonal bands (IgG-κ and IgG-λ). With the Hydrashift assay, the daratumumab-anti-daratumumab immune complex shifted the IgG-κ to the α zone, suggesting that the monoclonal IgG-κ band corresponded to daratumumab. Patient 2 was a 63-year-old male with IgG-κ MM who was receiving daratumumab once every other week. SPE/IF assay revealed a faint monoclonal IgG-κ band in the ï§ zone. A stronger monoclonal band was observed after administration. The IgG-κ band disappeared on the Hydrashift assay, while the daratumumab-anti-daratumumab complex appeared as a broad smear in the α-region. Patient 3, a 63-year-old male diagnosed with IgG-λMM, was receiving daratumumab once every other month. The IF assay showed two distinct bands (IgG-κ and IgG-λ) post-daratumumab administration. The shift to the α zone of the IgG-κ bands on the Hydrashift assay confirmed that the additional band observed post-infusion was due to the daratumumab. CONCLUSIONS: The Hydrashift assay can help distinguish daratumumab from endogenous M-spike.
Subject(s)
Immunoglobulin Light Chains , Multiple Myeloma , Male , Humans , Aged , Middle Aged , Immunoelectrophoresis/methods , Multiple Myeloma/diagnosis , Multiple Myeloma/drug therapy , Immunoglobulin G , ElectrophoresisABSTRACT
OBJECTIVE: To determine the role of bone marrow biopsy (BMBX), performed in association with comprehensive blood and imaging tests, in the evaluation of patients with fever of unknown origin (FUO). PATIENTS AND METHODS: We reviewed the medical records of 475 hospitalized patients who underwent BMBX in our medical center from January 1, 2005, to April 30, 2010. We identified 75 patients who fulfilled the accepted classic Petersdorf criteria for FUO. All patients underwent in-hospital investigation for fever, including chest and abdominal computed tomography. RESULTS: In 20 patients (26.7%), BMBX established the final diagnosis. Sixteen patients had hematologic disorders, including 8 patients with non-Hodgkin lymphoma, 2 with acute leukemia, 1 with multiple myeloma, 1 with myelodysplastic syndrome, and 4 with myeloproliferative disorders. The remaining patients with diagnostic BMBX specimens had solid tumors (2 patients), granulomatous disease (1 patient), and hemophagocytic syndrome (1 patient). Multivariate analysis revealed the following as the significant positive predictive parameters for a diagnostic BMBX specimen: male sex (odds ratio [OR], 7.35; 95% confidence interval [CI], 1.19-45.45), clinical lymphadenopathy (OR, 21.98; 95% CI, 1.97-245.66), anemia (OR, 2.21; 95% CI, 1.28-3.80), and increased lactate dehydrogenase levels (OR, 1.003; 95% CI, 1.001-1.006). CONCLUSION: Bone marrow biopsy is still a useful ancillary procedure for establishing the diagnosis of FUO, particularly if used in the appropriate clinical setting. Clinical and laboratory parameters associated with hematologic disease are predictive of a diagnostic BMBX specimen in patients with FUO.
