Snapshot A 7-year-old child presents to the emergency room for painful bumps on his knee. He had fallen a few days ago and scraped his knee. Since then, he has had increasingly painful bumps develop. There is some pus drainage but no erythema and no warmth. The lesions are cool to the touch. On physical exam, he is noted to have retained primary teeth, eczematous patches on his cheeks, and 2 cold abscesses on his right knee. He is started on antibiotics, and Ig levels are sent to the laboratory. Only IgE is elevated. A complete blood count with differential shows increased eosinophils. Introduction Clinical definition login to view 1 more bullet ETIOLOGY Pathogenesis login to view 1 more bullet Genetics login to view 2 more bullets Presentation Symptoms login to view 7 more bullets Physical exam login to view 10 more bullets Studies Diagnostic testing login to view 6 more bullets Differential Atopic dermatitis login to view 2 more bullets Severe combined immunodeficiency login to view 2 more bullets Diagnosis STAT3 genetic testing login to view 1 more bullet Treatment First-line login to view 7 more bullets Complications ↑ Risk of lymphoma Prognosis Average age of death of 29 years