Comprehensive Case Analysis: Diagnosing and Managing Myositis in Newly Diagnosed Systemic Lupus Erythematosus Patients in Indonesia.

An 18-year-old female with Systemic Lupus Erythematosus (SLE) presented with bilateral thigh pain, fever, and diarrhea three days before admission. Diagnosed with SLE one month earlier, she reported prior symptoms, including joint pain, malar rash, hair loss, and hyperpigmented lesions. Initial investigations revealed elevated transaminase levels (AST 355, ALT 132), positive ANA, decreased complement levels (C3 68, C4 16.8), and raised creatine kinase (619). A muscle biopsy confirmed myositis. The patient was treated with immunosuppressant (a combination of steroids and hydroxychloroquine) and supportive therapy. By the eighth day of hospitalization, her symptoms, especially thigh pain, resolved. Electromyocardiography was done, and the results were normal, indicating therapeutic success. This case highlights the importance of prompt diagnosis and management of myositis as a rare SLE manifestation to achieve favorable outcomes.