Morphological Characteristics of Idiopathic Inflammatory Myopathies in Juvenile Patients
Anne Schänzer,
Leonie Rager,
Iris Dahlhaus,
Carsten Dittmayer,
Corinna Preusse,
Adela Della Marina,
Hans-Hilmar Goebel,
Andreas Hahn,
Werner Stenzel
Affiliations
Anne Schänzer
Institute of Neuropathology, Justus Liebig University, 35392 Giessen, Germany
Leonie Rager
Institute of Neuropathology, Justus Liebig University, 35392 Giessen, Germany
Iris Dahlhaus
Institute of Medical Informatics, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin und Humboldt-Universität zu Berlin, 10117 Berlin, Germany
Carsten Dittmayer
Department of Neuropathology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
Corinna Preusse
Department of Neuropathology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
Adela Della Marina
Department of Pediatric Neurology, Centre for Neuromuscular Disorders, Centre for Translational Neuro-und Behavioral Sciences, University Duisburg-Essen, 45122 Essen, Germany
Hans-Hilmar Goebel
Department of Neuropathology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
Andreas Hahn
Department of Child Neurology, Justus Liebig University, 35392 Giessen, Germany
Werner Stenzel
Department of Neuropathology, Charité—Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin and Humboldt-Universität zu Berlin, 10117 Berlin, Germany
Background: In juvenile idiopathic inflammatory myopathies (IIMs), morphological characteristic features of distinct subgroups are not well defined. New treatment strategies require a precise diagnosis of the subgroups in IIM, and, therefore, knowledge about the pathomorphology of juvenile IIMs is warranted. Methods: Muscle biopsies from 15 patients (median age 8 (range 3–17) years, 73% female) with IIM and seven controls were analyzed by standard methods, immunohistochemistry, and transmission electron microscopy (TEM). Detailed clinical and laboratory data were accessed retrospectively. Results: Proximal muscle weakness and skin symptoms were the main clinical symptoms. Dermatomyositis (DM) was diagnosed in 9/15, antisynthetase syndrome (ASyS) in 4/15, and overlap myositis (OM) in 2/15. Analysis of skeletal muscle tissues showed inflammatory cells and diffuse upregulation of MHC class I in all subtypes. Morphological key findings were COX-deficient fibers as a striking pathology in DM and perimysial alkaline phosphatase positivity in anti-Jo-1-ASyS. Vascular staining of the type 1 IFN-surrogate marker, MxA, correlated with endothelial tubuloreticular inclusions in both groups. None of these specific morphological findings were present in anti-PL7-ASyS or OM patients. Conclusions: Morphological characteristics discriminate IIM subtypes in juvenile patients, emphasizing differences in aetiopathogenesis and supporting the notion of individual and targeted therapeutic strategies.
