Dermatomyositis as a Post-Covid Complication: Case Report

Dermatomyositis (DM) is a rare autoimmune inflammatory myopathy that affects the skin and skeletal muscles. Its typical manifestations include heliotrope rash and Gottron’s papules. Diagnosis is clinical and laboratory-based, including measurement of muscle enzymes and tests such as electromyography and muscle biopsy. Treatment is based on glucocorticoids and immunosuppressants, such as methotrexate, with biological therapies as alternatives in refractory cases. Since the COVID-19 pandemic, reports have suggested a possible association between SARS-CoV-2 infection and the onset of autoimmune diseases. It is believed that viral infection may trigger the disease through mechanisms such as type I interferon activation and molecular mimicry. This is a case report study based on medical record review, clinical evaluation, and complementary tests, in accordance with ethical principles of medical practice. A 49-year-old male patient, with a history of hospitalization for COVID-19 in February 2021, presented in March of the same year with low back pain, skin rash, arthralgia, and marked muscle weakness in the lower limbs. Physical examination revealed Gottron’s papules, shawl sign, heliotrope rash, and proximal muscle strength grade IV in both upper and lower limbs. A diagnostic hypothesis of DM was established. Complementary tests revealed CPK of 7,000 U/L, creatinine of 0.66 mg/dL, normal complete blood count, CRP of 2.9 mg/dL, and ESR of 25 mm. Electromyography demonstrated a myopathic pattern compatible with inflammatory myopathy. After confirmation of DM, treatment was initiated with prednisone at 1 mg/kg/day, the standard approach for rapid control of muscle inflammation. After 20 days of initial prednisone treatment, CPK levels decreased to 1,951 U/L. However, due to incomplete response to glucocorticoid monotherapy, methotrexate (MTX) 15 mg/week was added. After two months of combined treatment, a favorable clinical response was observed, with reduction of CPK levels to 118 U/L and progressive improvement of symptoms. This case highlights the potential of COVID-19 as a triggering factor for DM and emphasizes the importance of early recognition, appropriate treatment, and further research into the immunological mechanisms involved.