الفهرس 
INTRODUCTIONOnly 14 pages are availabe for public view
 |  | from | 78 |  |  |
| | | from | 78 | | |
Abstract
Histiocytosis constitutes a wide group of disorders that have in common the proliferation of cells of the mononuclear phagocyte and the dendritic cell systems. Macrophages have many crucial functions, including tissue remodeling, tumor suppression and promotion activities and in antigen-processing and immune stimulation; dendritic cells function primarily as antigen-presenting cells and immune system regulators.
HLH is the result of an uncontrolled immune response triggered by different stimuli such as infectious organisms, tissue damage, and metabolic products, on the basis of an underlying inherited or acquired inability to cope adequately with this trigger.
HLH is a clinical syndrome that can occur in different conditions and at all age groups. Multisystem inflammation is the main character of HLH and it is due to hypercytokinemia resulting from excess activation of lymphocytes and histiocytes. The main presenting symptoms are fever, splenomegaly and cytopenia.
HLH symptomatizes by many criteria, following the Histiocyte society recommendation for diagnosis of HLH 2004 five out of eight criteria should be fulfilled to establish HLH diagnosis or a molecular diagnosis consistent with HLH.
HLH has been divided into primary and secondary forms as it may have genetic causes or may be acquired under a variety of conditions. Primary HLH is also known as familial HLH, mostly autosomal recessive. This disease form occurs mostly in infants and very young children, due to immune defects, with genetic mutation in genes responsible for cytotoxic function of natural killer (NK) cells. Secondary form occurs in older children, adolescents, and adults, which is associated more often with infections, malignancies, auto-inflammatory and autoimmune diseases, and acquired immune deficiency conditions.
Macrophage activation syndrome (MAS) is a life-threatening complication of autoimmune diseases and may be classified as a subtype of secondary HLH. Patients with MAS may have special findings like neutrophilia or thrombocytosis in early disease stages, which are unusual in patients with primary HLH.(44) MAS is most frequent in systemic juvenile idiopathic arthritis, MAS can be the presenting sign of patients with autoimmune diseases and symptoms of such diseases (such as arthritis or rash) should be looked for cautiously.
HLH treatment is a double-edged sword: both hyper-inflammation and the destruction of remaining immune functions may be lethal for the patient. In genetic HLH, hematopoietic stem cell transplantation (HSCT) is indicated to replace the defective immune system with normally functioning cells.
Principles of treatment are Suppression of hyper-inflammation and searching for a treatable triggering factor is mandatory. Corticosteroids are the most important anti-inflammatory drugs for HLH. Immune-modulation by drugs such as cyclosporine A (CSA) or intravenous immunoglobulins (IVIG) and eliminating activated lymphocytes and infected antigen presenting cells by Etoposide (VP-16) are other goals of treatment.
The aim of this study was to study HLH cases admitted in the period from start of January 2016 to end of December 2016 at Alexandria University Children’s Hospital.
The study was conducted on 28 patients diagnosed as HLH during the period from start of January 2016 to end of December 2016. Patients records were the main source of study data and patients were followed up for a period of 28 month.
It was found that 53.6% were males while 46.4% were females, median age was 36 months, 21.4% had positive family history of similar condition. 57.1 % had positive consanguinity. All patients (either primary or secondary type) presented with fever, 89.36% had hepatosplenomegaly, cytopenia was present in 64.28%, hypertriglyceridemia was present in82.14% while hyperferritinemia was present in 78.6% and sCD25 was present in 96.4%, low fibrinogen level was present in 67.85% of the study cases.
Only 25% survived either after HSCT in primary disease cases or after control of the primary cause in secondary disease cases, most of dead patients 50% died due to sepsis which indicates need for more aggressive supportive treatment including good antibiotic treatment, isolation, IVIG, and good infection control measures