A Fatal Case of Familial Hemophagocytic Lymphohistiocytosis Associated with Fusarium Infection and Rare Mutation

Background: Hemophagocytic lymphohistiocytosis (HLH) is classified as primary or secondary. While primary (familial) HLH is caused by genetic mutations, secondary (acquired, reactive) HLH is the type that has an underlying cause and is not associated with genetic mutations.Case Report: We report a two-year-old female patient with a fatal course of Fusarium sepsis who was diagnosed with primary HLH. A homozygous variant of PRF1 (c.445G > A, p.Gly149Ser) was detected. Hyphal growth was detected on Sabouraud dextrose agar and Fusarium multiplied in blood cultures. The patient's clinical course was fulminant, and she died of septic shock 4 days after admission to the hospital. Fusarium, a rare infection in HLH, was found in this case.Conclusion: We discovered the rare PRF1 (c.445G>A, p.Gly149Ser) mutation in HLH and the high morbidity and mortal-ity associated with Fusarium infection.