Case Report of a Rare Association: Adult‐Onset Still's Disease With Inflammatory Myositis

A 33-year-old female presented with a 9-month history of dry cough, episodic high-grade fever, polyarthralgia, decreased appetite, and weight loss. She had mediastinal and abdominal lymphadenopathy and hepatosplenomegaly. Empirical antitubercular therapy, started elsewhere, wasn't helpful. When she presented to us, she had neck, truncal, and symmetrical proximal muscle weakness, malar erythema, cervical lymphadenopathy, and multiple tender joints. The initial differentials included lupus or inflammatory myositis. She had leukocytosis (22 900/mm3, neutrophils-87%), elevated SGOT and SGPT (311/62 U/L), and LDH (915 U/L), normal creatine kinase (44 U/L), and elevated ESR (60 mm/h). ANA was negative, and bone marrow examination was unremarkable. MRI showed patchy edema in bilateral thigh muscles (Figure 1A–D). On reviewing, she gave a history of transient salmon-pink rash over her limbs at the onset of illness (Figure 1E). Serum ferritin was elevated (98 575 ng/mL), and a diagnosis of AOSD was made. Fever subsided with the initiation of glucocorticoids and methotrexate, but muscle weakness responded when methotrexate was changed to monthly pulse cyclophosphamide. Myositis is rarely reported in association with AOSD [1, 2]. Our case highlights this rare association and the successful use of intravenous cyclophosphamide in controlling the disease. Whether muscle involvement stems from AOSD-related systemic inflammation or is an overlap with autoimmune myositis needs to be explored. The author takes full responsibility for this article. The authors have nothing to report. The authors have nothing to report. Patient consented to provide the data for publication. The authors declare no conflicts of interest. The data that support the findings of this study are available from the corresponding author upon reasonable request.