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[Clinical analysis and follow-up study of Epstein-Barr virus associated-hemophagocytic lymphohistiocytosis in childhood].

OBJECTIVE
To identify the clinical characteristics of and to explore the prognostic factors influencing mortality in children with Epstein-Barr virus-associated hemophagocytic lymphohistiocytosis (EBV-HLH).


METHOD
A retrospective study was conducted on 62 pediatric patients with EBV-HLH who were admitted to our hospital between 2003 and 2008. All their medical records were reviewed and analyzed. For each patient, demographic, clinical and laboratory data, genetic findings and outcome information were collected. The patients were divided into two groups: deceased or survived based on the follow-up results. Comparative analysis of the data was done by using independent-samples t test and Logistic multiple and univariate regression.


RESULT
(1) Among the 62 EBV-HLH patients, 36 were male and 26 were female. The age of onset ranged from 2 months to 14 years and most of the patients were between 1 and 3 years of age. EBV-HLH occurred mainly in the setting of reactivation (61.3%). (2) All patients exhibited persistent or intermittent fever and cytopenia >/= 2 cell lines. Most of the patients presented with hepatomegaly (83.9%), splenomegaly (72.6%) and lymphadenopathy (69.4%). The main laboratory features showed an elevation of serum ferritin and aminotransferase levels. A reduction in serum albumin was observed and exhibited coagulopathy with hypofibrinogenemia and hypertriglyceridemia in most of the patients. Forty-eight of patients had hemophagocytosis in bone marrow at diagnosis of EBV-HLH. The serum EBV DNA level in 14 of 31 patients with EBV-HLH was in the range of 5.12 x 10(2) - 7.69 x 10(7) copies/ml with a mean value of 10(3.9) copies/ml. (3) Three heterozygous mutations in coding region were found, which resulted in amino acid change (C102F, S108N and T450M) in 3 patients. One patient had compound heterozygous mutations (S108N and T450M) in the PRF1 gene as the background defect and documented familial HLH type 2 (FHL2). (4) During the observational period, 35 of 57 patients (61.4%) died 3 months to 3 years after the onset, while 21 of whom died despite aggressive polychemotherapy, 15 of whom died within 2 months after hospitalization. The deceased patients were more likely to have lower albumin level and more prolonged activated partial thromboplastin time than the survived patients (P < 0.05 for all comparisons). Multivariate Logistic regression analysis revealed that duration of illness >/= 1 month, non-chemotherapy, albumin level < / = 25 microg/L and internal organs hemorrhage were related with the prognosis significantly (P < 0.05 for all comparisons).


CONCLUSION
This study revealed that EBV-HLH infection in pediatric patients had severe clinical courses and prognosis was poor and the majority of cases underwent EBV reactivation. The early diagnosis, prompt and proper chemotherapy can improve the survival rate. The duration of illness >/= 1 month, non-chemotherapy, decreases in albumin and internal organs hemorrhage were the risk factors related to mortality in children with EBV-HLH.