Cutaneous clues to diagnosis: the vasculopathic form of anti-MDA5dermatomyositis

Anti- melanocyte differentiation-associated protein 5 (MDA5) associated dermatomyositis is a rare, heterogeneous disease with multiple phenotypes. This case describes a patient with indolent myopathy, skin lesions and normal creatine kinase (CK). After a period of diagnostic uncertainty, the patient was found to have positive anti-MDA5 and anti-Ro52 antibodies, confirming anti-MDA5 dermatomyositis with cutaneous vasculopathy. Recognition of vasculopathy as a manifestation of dermatomyositis could have led to a much earlier diagnosis. The European Alliance of Associations for Rheumatology /American College of Rheumatology classification criteria can aid diagnosis. Antibody profile correlates with disease phenotype in dermatomyositis. Anti-MDA5 dermatomyositis is typically associated with rapidly progressive interstitial lung disease and amyopathic dermatomyositis. Some patients may present with myopathy despite a normal CK. Vasculopathic skin lesions are common, but frequently under-recognised, and can develop from Gottron's papules. All phenotypes are associated with increased morbidity and mortality. This underscores the importance of recognising such vasculopathy as a sign of anti-MDA5-associated dermatomyositis, thus contributing to earlier diagnosis and treatment.