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Question: Fever + rash

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You are seeing a 3 year old girl who was discharged from the hospital a week ago. At that time, she presented with fever, intermittent polyarthralgias, and an evanescent salmon pink rash. She was diagnosed with new onset systemic juvenile idiopathic arthritis, treated with ibuprofen, and initially did well. She now presents with unremitting fever and rash, bruising, petechiae, gum bleeding, hepatosplenomegaly, and lethargy. Labs reveal elevated transaminases, ferritin, LDH, and triglycerides, but a low ESR.

Which of the following is the most likely diagnosis?

pemsou5_wp • September 21, 2021

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  1. Kelly September 22, 2021 - 12:35 am Reply

    B) Macrophage activation syndrome
    MAS is a life-threatening complication of rheumatic diseases, most commonly systemic JIA, similar to hereditary lymphocytic hematophagocytosis (HLH). MAS usually occurs within days to weeks of the initial diagnosis of JIA but can occur any time. There is a paradoxic low/normal ESR due to fibrinogen consumption. Scoring tools are available to help differentiate MAS from a systemic JIA exacerbation and from HLH. MAS is treated with high-dose methylprednisolone 30 mg/kg IV (max 1g). Patients are admitted to a PICU for supportive care.

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