Abstract: ObjectiveTo improve the diagnosis and treatment of familially hemophagocytic lymphohistiocytosis (FHL). MethodsOne patient with FHL confirmed by diagnosis was presented and relevant FHL cases reported in China and abroad were combined to gather and analyze the clinical characteristics. ResultsFHL2 was often associated with PRF1 gene mutations， about 20%40% of the patients was in perforin gene mutations. ConclusionFor patients with positive family history  and clear  genetic diagnosis， chemotherapy or hematopoietic stem cell transplantation is needed as soon as possible. Without a family history， the primary cause of associated with secondary HLH was unknown， genetic screening can be considered in order to make clear  the possibility of FHL.

Key words: lymphohistiocytosis, hemophagocytic, diagnosis, differential, treatment outcome, perforin