Amyopathic dermatomyositis: a case report

Introduction: Systemic autoimmune myopathies are rare systemic diseases that can present with a clinical picture of progressive muscle weakness and histopathologic findings of varying degrees of inflammatory infiltrates in muscle tissue. Subtypes of systemic autoimmune myopathies include: dermatomyositis (DM), polymyositis (PM), myositis as part of a rheumatic disease overlap syndrome, antisynthetase syndrome myositis, immune-mediated necrotizing myopathy (IMNM), and inclusion body myositis (IBM). Dermatomyositis mainly affects patients in adulthood, and is characterized by a picture of loss of strength, skin findings and laboratory alterations, with possible autoantibody positivity, as well as pulmonary, gastrointestinal and cardiac involvement. Among the subtypes of dermatomyositis, one can highlight the Amyopathic Dermatomyositis, in which the characteristic muscle involvement is not present and can be evidenced by the absence of alteration in electroneuromyography and muscle enzymes creatine phosphokinase (CPK), lactate dehydrogenase (LDH), aldolase aspartate aminotransferase (AST) and alanine aminotransferase (ALT). However, skin changes may be present (Gottron papules, Gottron sign, heliotropic rash) and there may be pulmonary involvement such as Interstitial Lung Disease. Treatment should consist of a multifaceted approach to obtain a satisfactory response in the cutaneous manifestations of DM, associated with systemic drugs aimed at achieving sustained control of the disease such as hydroxychloroquine and methotrexate. Objective: Report a case of amyopathic dermatomyositis, describing the follow-up of the case, from diagnosis to therapy, aiming to provide more data on the subject, since it is a rare disease. Methods: The data for this case report were collected from medical records, test results and photographic records of meetings with the patient, with authorization from the clinical director of Hospital Emilio Carlos and signature of the informed consent form by the patient.Result: A 60-year-old female patient was admitted to our service complaining of skin lesions and dyspnea. When undergoing rheumatologic evaluation, it was found that the patient had lesions characteristic of dermatomyositis (gottron papules and heliotrope). Upon further investigation, pulmonary involvement of the fibrosis type was discovered with positivity of the anti-Jo1 antibody, but there were no changes in muscle enzymes or in the electroneuromyography examination. In view of this, the diagnosis of amyopathic dermatomyositis was made and treatment for skin lesions and interstitial lung disease was initiated.Conclusion: Amyopathic dermatomyositis is a very rare and difficult-to-diagnose disease, with few cases described so far. Our report aims to contribute to the literature and draw attention to potential diagnoses based on physical, laboratory and imaging findings.