Acute encephalopathy as a primary manifestation of haemophagocytic lymphohistiocytosis

Haemophagocytic lymphohistiocytosis (HLH) is characterized anatomically by an infiltration of multiple tissues with lymphocytes and haemophagocytic hi stiocytes. First symptoms are usually hepatosplenomegaly, pancytopenia, and intractable fever. Up to 73% of those with HLH develop CNS involvement dur ing the disease course. The peculiarity of the two patients presented here, a 20-month-old Italian female and a 4-year-old Moroccan female, is that th e initial presenting neurological symptoms mimicked an encephalitis, antici pating the typical systemic symptoms by 1 and 4 months. They developed prog ressive encephalopathy accompanied by status epilepticus, one child develop ed a secondary hydrocephalus. In both children it was not possible to detec t an underlying infection or malignant disease and there were no other case s in the family that suggested a familial form of HLH. Diagnosis and initia tion of treatment was delayed because of the initial encephalopathic clinic al picture and the late onset of the typical systemic features. As early di agnosis allows better therapeutical approaches, haemophagocytic lymphohisti ocytosis should be considered in children with persistent or progressive fi ndings of encephalopathy, especially in the absence of identification of a plausible pathogen.