Fatal myocarditis in a child with systemic onset juvenile idiopathic arthritis during treatment with an interleukin 1 receptor antagonist

An eleven year-old boy with soJIA died suddenly while being treated with the interleukin 1 (IL-1) receptor inhibitor, anakinra. His autopsy revealed an enlarged heart and microscopic findings were consistent with myocarditis, but not pericarditis. Viral PCR testing performed on his myocardial tissue was negative.This case illustrates myocarditis as a fatal complication of soJIA, potentially enabled by anakinra.Systemic onset juvenile idiopathic arthritis (soJIA) is a chronic auto-inflammatory disease of childhood characterized by quotidian fever, evanescent rash, serositis, lymphadenopathy, splenomegaly, and synovial joint inflammation [1]. Isolated myocarditis without pericardial involvement has been described in SoJIA [2], and individuals with active soJIA have been described with signs of heart failure in the absence of overt pericardial effusion [3]. Cardiac death has occurred in a patient with adult-onset Still's disease treated with IL-1 receptor inhibitor, anakinra [4]. We present a child with soJIA who died unexpectedly while receiving anakinra whose autopsy revealed an inflammatory myocarditis without pericarditis.A 10 year-old adopted, African American boy with a history of autism and asthma presented to our pediatric rheumatology clinic with a pruritic evanescent erythematous macular rash, polyarticular large and small joint arthritis, subjective fever in a quotidian pattern, 10 pound weight loss and fatigue, and cervical lymphadenopathy. His electrocardiogram was within normal limits. His blood work revealed leukocytosis with a predominance of neutrophils (WBC 17 K/μL, neutrophils 84%), normocytic anemia (Hbg 9.9 g/dL), mild thrombocytosis (452 K/μL), and normal creatinine, uric acid, LDH, and complement levels. Signs of systemic inflammation were evident (ESR 80 mm/h, CRP 14 mg/dL, d-dimer 2890 ng/mL, soluble IL-2 receptor 1058 U/mL, ferritin 673 ng/mL). His urine revealed 12 RBC's, mild microscopic hematuria, and normal calcium creatinine ratio. An abd