Neurological involvement in secondary hemophagocytic lymphohistiocytosis in children

To describe neurological characteristics and CNS involvement on MRI in secondary hemophagocytic lymphohistiocytosis (sHLH) and differentiate it from primary hemophagocytic lymphohistiocytosis (pHLH) and acute disseminated encephalomyelitis (ADEM).

Nine children with sHLH who had neurological symptoms were retrospectively included. Characteristics of brain MRI were compared to those of 15 children with pHLH and neurological involvement and 44 children with ADEM.

Three children (33%) presented with isolated neurological symptoms. Neurological signs occurred within one month following Epstein-Barr virus primary infection or systemic juvenile arthritis exacerbation in 8 patients (89%). Eight children (89%) had MRI lesions. sHLH MRI lesions were distinct of those of pHLH by morphology and signal with more frequent hyposignal intensities on T1-weighted sequences (p = 0.01) and well-defined and less fuzzy lesions (p = 0.03). All patients survived and one patient presented severe motor and cognitive disability.

Neurological symptoms of sHLH are non-specific and their outcome is favorable in most of the children. MRI at onset may help to differentiate this condition from pHLH.