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Background: We report a case of immunoglobulin (Ig) D myeloma with hidden lambda light chains in a patient whose immunofixation test was very difficult to interpret: the IgD reacts with the anti-δ heavy chain antiserum but does not react with anti-lambda antiserum. The band in the D heavy chain lane is unmatched in light chain lanes and the band in lambda light chain lane migrates higher. Methods: To distinguish between heavy chain disease and immunoglobulin with "hidden" light chains, the sample was exposed to a very high concentration of anti-lambda and anti-kappa antisera for 48 hours. Results: The serum immunofixation test of the sample treated with anti-lambda showed a decrease in the intensity of the band corresponding to D heavy chain lane as well as the modification of its mobility confirming the presence of IgD with the hidden lambda light chains. Conclusions: The IgD myeloma with hidden light chains remains a rare entity, hence the interest of sensitizing health professionals to be vigilant and ensure a good diagnosis. The proposed technique is useful, simple, reliable, and less laborious than those previous reported in the literature. Medical laboratories using Sebia-Hydrasys® system should be aware of the described phenomenon in order to avoid identifying an IgD myeloma as a delta heavy chain disease. [ABSTRACT FROM AUTHOR]

Introduction: Multiple sclerosis and other inflammatory diseases of the central nervous system produce various and nonspecific symptoms. The diagnosis of these diseases is ultimately a clinical decision, although examination of cerebrospinal fluid (CSF) and other complementary tests such magnetic resonance imaging (MRI) and evoked potentials can be contributive. One important aspect of these diseases is intrathecal synthesis of immunoglobulins., Patients and Methods: In order to determine the contribution of CSF/serum immunofixation to the diagnosis of inflammatory diseases of the central nervous system, we conducted a retrospective study in the biochemistry laboratory of the military instruction hospital Mohammed V. 363 CSF/serum samples were collected over a period of four years., Results: Immunofixation was less sensitive than MRI for the diagnosis of inflammatory neurological disease (44% vs 87%), but was much more specific than MRI (97% for immunofixation vs 38%). The positive predictive value was higher that for MRI (85% vs 40%). The negative predictive value (80%) was close to that of MRI (86%). The bivariate analysis showed that immunofixation results could be predicted from clinical findings and complementary test results such as the index of Link, syphilis serology in CSF, and MRI., Conclusions/discussion: Semi-automatic Hydrasys immunofixation of CSF IgG is a technique exhibiting excellent diagnostic and analytical performance for the diagnosis of inflammatory neurological diseases., (Copyright © 2010. Published by Elsevier Masson SAS.)