الفهرس 
OVERVIEW OF HEMOPHAGOCYTIC LYMPHOHISTIOCYTOSISOnly 14 pages are availabe for public view
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Abstract
Background: Familial hemophagocytic lymphohistiocytosis (HLH) results in clinical manifestations of an extreme inflammatory process; leading to an overlap with other diseases with a hyperinflammation process. Implementing HLH criteria without genetic analysis might lead to inadvertent planned therapy with immunosuppressive and unnecessary bone marrow transplantation.
Objectives: This study assessed the frequency and types of UNCD mutations among patients fulfilling criteria of HLH and correlated between the genetic mutations and with severity of the disease and its clinical picture.
Methods: This study included 40 patients with suspected HLH with median age 28 months. All included patients were subjected to detailed medical history and clinical examination. All patients fulfilled at least two out of 7 of HLH criteria. Complete blood count, liver enzymes, total and direct bilirubin, serum ferritin, serum fibrinogen, serum triglycerides, sCD25, bone marrow aspirate, MRI brain and CSF analysis were assessed as well as analysis of UNC13D gene were performed.
Results: The studied population were 24 (60%) males and 16 (40%) females with mean age at initial presentation being 38.34 months. Eighteen (45%) patients had a positive family history. At presentation, 25 (62.5%) patients had systemic manifestations, nine (22.5%) presented with neurological manifestations and six (15%) patients had both systemic and neurological manifestations. As regards the treatment, 36 (90%) patients received corticosteroids, 29 (72.5%) patients received etoposide.There was a time lag before starting the treatment and reaching the final diagnosis as the duration between start of symptoms and start of steroids was 168 days, while duration between start of symptoms and final diagnosis was 203 days. Final diagnosis of the studied population was as follows; 15 (37.5%) patients were found to be non-UNC13D FHLH, 10 (25%) patients had UNC13D gene mutation, 4 (10%) had secondary HLH, one patient (2.5%) had sepsis, one patient (2.5%) had immune deficiency and sepsis, 3 patients (7.5%) had other diagnoses and 6 (15%) patients had unknown diagnoses. Nearly one third of patients (n=11, 30.6%) were misdiagnosed as FHLH which was then excluded by genetic study. 8 (32%) patients were diagnosed solely by genetic study to have FHLH and were not suspected upon presentation to have FHLH.
Conclusions: Genetic testing is mandatory for diagnosis of FHLH and to differentiate from other conditions with hyperinflammatory process.