Integrated classification of inflammatory myopathies

Abstract

Inflammatory myopathies comprise a multitude of diverse diseases, most often occurring in complex clinical settings. To ensure accurate diagnosis, multidisciplinary expertise is required. Here, we propose a comprehensive myositis classification that incorporates clinical, morphological and molecular data as well as autoantibody profile. This review focuses on recent advances in myositis research, in particular, the correlation between autoantibodies and morphological or clinical phenotypes that can be used as the basis for an 'integrated' classification system.

Diagnostic potential of sarcoplasmic myxovirus resistance protein A expression in subsets of dermatomyositis

“…The sensitivity and specificity for overall DM patients (respective 77% and 100%) were consistent with those in the previous study using a different cohort which revealed 71% of sensitivity and 98% of specificity , further corroborating its high potential as a pathological marker for DM. Although pathological changes of DM are generally conspicuous in perifascicular areas , myofibres with MxA overexpression were seen beyond perifascicular regions in nearly half of the DM samples positive for sarcoplasmic MxA expression, representing the value of MxA immunostaining to increase diagnostic sensitivity and accuracy. Practically, improvement of pathological diagnosis for DM without PFA is particularly important.…”

“…ASS is associated with anti‐aminoacyl transfer RNA synthetase autoantibodies and clinically with myositis, characteristic skin lesion (mechanic's hands are typical, but heliotrope rash and Gottron's signs/papules can also be seen), Raynaud phenomenon, interstitial lung disease, arthritis/arthralgia, and systemic symptom such as fever . Some of the clinical features and a pathological finding of perifascicular reinforcement of human leucocyte antigen (HLA)‐ABC [major histocompatibility complex (MHC) class I] expression on the sarcoplasm are shared with DM, yet ASS has a unique myopathological phenotype.…”

“…A diagnosis of dermatomyositis (DM) is achieved multidisciplinarily by clinical evaluation, autoantibody measurement in sera and morphological analysis of skeletal muscle . Muscle biopsy plays an important role to validate and complement clinical and serological diagnosis, and to diagnose clinically atypical or seronegative patients.…”

“…However, the sensitivity of PFA is limited, mainly because muscle biopsy samples of DM patients may not always include PFA due to its patchy distribution or due to poorly affected biopsy site . Also, PFA or PFA‐like lesions can be seen in antisynthetase syndrome (ASS) . Although mostly small regenerating fibres in perifascicular regions make up the lesion, it may occasionally be difficult to clearly differentiate between PFA of DM and that of ASS‐associated myositis or other inflammatory myopathies harbouring atrophic fibres in the periphery of the fascicles (e.g.…”

“…Here, we specifically address the issue of sarcoplasmic MxA expression in subsets of DM defined by the DM‐specific autoantibodies. Since each of these DM subsets harbours particular features in muscle pathology as well as clinical aspects , it will be significant to clarify whether MxA staining patterns differ in these subgroups.…”