Prolonged course of familial hemophagocytic lymphohistiocytosis.

Familial hemophagocytic lymphohistiocytosis is usually diagnosed in the first 2 years of life and, if untreated, is rapidly fatal. We describe a 10-year-old boy with a 9-year history of prolonged fever and progressive hepatosplenomegaly who was diagnosed as having hemophagocytic lymphohistiocytosis 2, being homozygote to a previously described mutation in the PRF1 gene, and cured by the HLH-2004 protocol and allogenic bone marrow transplantation. This unique case emphasizes the heterogeneity of this disease and the diversity of its clinical presentations.