Hemophagocytic lymphohistiocytosis with Munc13-4 mutation: a cause of recurrent fatal hydrops fetalis.

Familial hemophagocytic lymphohistiocytosis (FHL) is an autosomal recessive disorder of immune regulation that leads to a hyperinflammatory syndrome responsible for fever, hepatosplenomegaly, cytopenia, and coagulopathy. Although presentation usually occurs in early infancy, antenatal presentation is extremely rare. To our knowledge, we are first to report genetically confirmed FHL in 2 consecutive siblings who presented with hydrops fetalis that led to spontaneous intrauterine death at 38 and 30 weeks of gestation. Because the diagnosis of FHL has important implications for genetic counseling, we suggest that FHL be considered in the differential diagnosis of nonimmune hydrops fetalis.