Disease Information for Hemophagocytic lymphohistiocytosis (HLH)

Known also as sinus histiocytosis/massive lymphadenopathy syndrome; Hemophagocytic lymphohistiocytosis (HLH) is a rare immunologic disorder which is often fatal if not diagnosed and treated properly; HLH is currently described as either the"primary" (familial) form or the "secondary" forms associated with infections, malignancies, and "reactive" HLH associated with rheumatologic disorders (macrophage activation syndrome - MAS); Symptoms of primary (familial) HLH are usually evident within the first several months of life and may even develop in utero; Symptomatic presentation throughout childhood and even into young adulthood has been observed in familial cases, although this is less common; It is difficult to differentiate primary from secondary cases of HLH on the basis of symptoms, which are very similar; The onset of familial HLH is often associated with documented infection; Symptoms of HLH triggered by infection with Epstein Barr virus (EBV) may also be the first sign of other known immunodeficiency disorders in children and young adults, such as X-linked lymphoproliferative syndrome in boys; Thus, any case of primary or secondary HLH should be considered for genetic testing; pathology is lack of NK cells and cytotoxic T cells function which ar critical for virus defence

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