The diagnosis and classification of amyopathic dermatomyositis: a historical review and assessment of existing criteria

Abstract

Background Diagnostic criteria are used to identify a patient having a disease in a clinical setting, whereas classification criteria create a well-defined population for research purposes. The diagnosis and classification of amyopathic dermatomyositis (ADM) have not been recognized by most existing criteria for idiopathic inflammatory myopathies (IIMs). To address this, several criteria were proposed to define ADM either as a distinct disease entity or as a subset of the spectrum of IIMs. Objectives To discuss the diagnosis and classification of ADM and to assesses the available criteria in identifying cases of ADM and/or distinguishing it from dermatological mimickers such as lupus erythematosus. Methods We conducted an extensive literature search using the PubMed database from June 2016 to August 2018, using the search terms 'amyopathic dermatomyositis', 'diagnosis' and 'classification'. Results The European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) criteria, which are the only validated classification criteria for adult and juvenile IIM and their major subgroups, include three cutaneous items (G€ ottron sign, G€ ottron papules, heliotrope rash) to be able to classify ADM. This international and multispecialty effort is a huge step forward in the classification of skin-predominant disease in dermatomyositis. However, about 25% of the population with ADM do not meet two out of the three skin features and are misdiagnosed or classified as having a different disease entity, most commonly lupus erythematosus. Conclusions These gaps rationalize the continuous assessment and improvement of existing criteria and/or the development of validated, separate and skin-focused criteria for DM. What's already known about this topic?• The diagnosis and classification of amyopathic dermatomyositis (ADM) have not been recognized by most existing criteria for idiopathic inflammatory myopathies (IIMs).• The latest validated European League Against Rheumatism (EULAR)/American College of Rheumatology (ACR) criteria perform well in capturing the majority of the ADM population using three skin variables: G€ ottron sign, G€ ottron papules and heliotrope rash.• However, about 25% of patients with ADM do not meet two out of the three skin features and fail the classification.What does this study add?• The gaps in the existing classification and diagnostic criteria for IIMs rationalize the continuous assessment and improvement of existing criteria and/or the development of validated and skin-focused criteria for DM. Diagnosis and classification of amyopathic dermatomyositis, J.S.S. Concha et al. 1003Heliotrope rash, G€ ottron papules, G€ ottron sign Heliotrope rash (blue-purple discoloration on the upper eyelids with or without associated oedema) Erythematous rash on the face, neck, anterior chest (V-sign) or back and shoulders (shawl sign), knees, elbows and malleoli Mechanic's hands (rough and cracked lateral and palmar areas of the fingers) Photosensitivity and pruritus

Developing classification criteria for skin‐predominant dermatomyositis: the Delphi process

“…) . The project started with an extensive literature search on and evaluation of the existing criteria for DM . This step in criteria development has previously been described in detail .…”

“…The project started with an extensive literature search on and evaluation of the existing criteria for DM . This step in criteria development has previously been described in detail . The literature review also involved previous extensive work on the DM lexicon for CADM .…”

“…The literature review also involved previous extensive work on the DM lexicon for CADM . Basically, gaps in the available criteria were identified, which justified the need to develop skin‐focused criteria for DM . Data gathered from this search guided the generation of items for inclusion in the Delphi exercise.…”

“…4 This step in criteria development has previously been described in detail. 4 The literature review also involved previous extensive work on the DM lexicon for CADM. 9,16 Basically, gaps in the available criteria were identified, which justified the need to develop skinfocused criteria for DM.…”

Amyopathic dermatomyositis – a ‘feel‐good’ dermatology story

“…In this issue of the BJD , Concha and colleagues review the history surrounding the recognition and characterization of amyopathic dermatomyositis (ADM), detail its clinical and serological features, and assess updated criteria concerning its diagnosis in affected patients . This is a story that dermatologists should be proud to read, as it underscores the critical role our specialty plays in advancing understanding of dermatomyositis (DM) specifically and connective tissue diseases more generally.…”