1st APLAR Grand Round 2022 Blackboard

CASE

A 20-year-old female patient with a history of juvenile idiopathic arthritis (JIA) presented with fever and maculopapular rash. The spleen tip was palpable on physical examination. Which of the following is most useful in distinguishing JIA complicated with macrophage activation syndrome (MAS) from JIA without MAS?

Your Answer is Incorrect

Answer with Detailed explanation

Fibrinogen gets consumed in MAS, leading to falling ESR which can be an early laboratory finding in systemic JIA complicated by MAS. A ferritin: ESR ratio of 21.5 was 82% sensitive and 78% specific for diagnosing systemic JIA complicated by MAS versus active systemic JIA without MAS. Ferritin alone with a set sensitivity of 95% (screening tool) had an 89.3% specificity of identifying all-cause MAS versus febrile hospitalized children.

Reference:
Eloseily EMA, Minoia F, Crayne CB, Beukelman T, Ravelli A, Cron RQ. Ferritin to Erythrocyte Sedimentation Rate Ratio: Simple Measure to Identify Macrophage Activation Syndrome in Systemic Juvenile Idiopathic Arthritis. ACR Open Rheumatol. 2019 Jul 13;1(6):345-349.

By Prof Gregory Cheng, Professor, Macau University of Science of Technology, Macau