Severe rhabdomyolysis due to idiopathic inflammatory myopathies, a wary manifestation of a heterogenous pathology.

Idiopathic inflammatory myopathies (IIM) are historically classified by The Bohan and Peter criteria. The presentation of IIM is versatile and clinical-serological findings can aid in diagnosing the underlying form of IIM. Over the past years, the discovery and the use of myositis-specific autoantibodies (MSA) and myositis-associated autoantibodies (MAA) have led to a more heterogeneous classification by the European League Against Rheumatism and American College of Rheumatology (EULAR/ACR).This paper describes a case of dermatomyositis sine dermatitis. A 70-year -old woman presented with complaints of muscle weakness and was admitted because of severe oliguric renal failure due to rhabdomyolysis. Despite treatment with hemodialysis and initial recovery, her clinic worsened again. The disease course in combination with electromyography findings, PET-scan results, and positive myositis-specific autoantibodies, that is, anti-NXP-2 antibodies, ultimately led to the diagnosis.Today, commercial kits based on line immunoassay and dot blot have mostly replaced the labor-intensive immunoprecipitation of RNA and/or proteins for detecting MSA. Though it makes routine testing of multiple MSA easy to implement in clinical practice, more validation studies are required and clinicians should be aware of its limitations, including false-positive results. When clinical suspicion for IIM is high, a negative screening for antinuclear antibodies (ANA) result does not exclude IIM and the first test of choice remains a multi-specific immunoassay for the whole spectrum of MSA.In this paper, we want to underline that there is no shortcut in diagnosing IIM. Caution is required in interpreting different EMG, PET-scan, histological, and laboratory findings. Especially in the case of rhabdomyolysis, as this is a severe and wary manifestation of myositis.

Performance of Abbott Alinity hq hematology analyzer for automated cell counting of body fluids.

INTRODUCTION: Body fluid cell counting and differentiation provide essential information for diagnosis and monitoring of diverse pathologies. We evaluated the performance of the newly launched Abbott Alinity hq hematology analyzer for automated cell counting in body fluids and compared red blood cell (RBC) and total nucleated cell (TNC) counts with the Cell-Dyn Sapphire automated hematology analyzer. Differential counts were compared with microscopic differentiation on cytocentrifuged preparations. METHODS: Background concentration limits, limit of detection (LOD), linearity, imprecision, functional sensitivity and carryover were evaluated. For method comparison, we collected 172 body fluids (17 continuous ambulatory peritoneal dialysis fluids, 56 cerebrospinal fluids and 99 serous fluids). RESULTS: Background concentration limits were ≤1000 cells/µL for RBC counts and ≤3 cells/µL for TNC counts. The LOD was 1000 RBC/µL and 5 TNC/µL. Results from linear regression analysis revealed excellent linearity. Functional sensitivity was 3000 cells/µL for RBC counts and 50 cells/µL for TNC counts. Carryover was 0.6% and 0.1% for TNC and RBC, respectively. The Alinity hq shows good clinical performance. CONCLUSION: We demonstrated comparable performance for body fluid cell counting between the Alinity hq analyzer and the Cell-Dyn Sapphire. The Alinity hq can be very useful as a screening tool for body fluid cell counting.

Humoral Immune Response to SARS-CoV-2.

OBJECTIVES: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) serology tests are clinically useful to document prior SARS-CoV-2 infections. Data are urgently needed to select assays with optimal sensitivity at acceptable specificity for antibody detection. METHODS: A comparative evaluation was performed of 7 commercial SARS-CoV-2 serology assays on 171 sera from 135 subjects with polymerase chain reaction-confirmed SARS-CoV-2 infection (71 hospitalized patients and 64 paucisymptomatic individuals). Kinetics of IgA/IgM/IgG seroconversion to viral N and S protein epitopes were studied from 0 to 54 days after onset of symptoms. Cross-reactivity was verified on 57 prepandemic samples. RESULTS: Wantai SARS-COV-2 Ab ELISA and Orient Gene COVID-19 IgG/IgM Rapid Test showed superior overall sensitivity for detection of SARS-CoV-2 antibodies. Elecsys Anti-SARS-CoV-2 assay and EUROIMMUN Anti-SARS-CoV-2 combined IgG/IgA showed acceptable sensitivity (>95%) vs the consensus result of all assays from 10 days post onset of symptoms. Wantai SARS-COV-2 Ab ELISA, Elecsys Anti-SARS-CoV-2 assay, and Innovita 2019-nCoV Ab rapid test showed least cross-reactivity, resulting in an optimal analytical specificity greater than 98%. CONCLUSIONS: Wantai SARS-COV-2 Ab ELISA and Elecsys Anti-SARS-CoV-2 assays are suitable for sensitive and specific detection of SARS-CoV-2 antibodies from 10 days after onset of symptoms.