Hemophagocytic lymphohistiocytosis: a missed diagnosis in pediatric intensive care units

Background Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening condition that shares common features with severe sepsis. This study aimed to report the number of children with suspected HLH in a pediatric intensive care unit (PICU) and to compare clinical and laboratory criteria of patients who met the HLH criteria versus those who did not meet HLH criteria to determine the red flags suggesting HLH. Patients and methods This retrospective study included all patients admitted to the PICU of the Alexandria University Children’s Hospital in Egypt, over four years from January 2016 to December 2019. Patients were screened for the presence of fever, splenomegaly, and cytopenias; if positive, they were considered as clinically suspected HLH and included in the study. Results Among 1056 patients admitted to PICU during the study period, 54 (5.1%) patients have been identified as clinically suspected HLH. Patients’ ages ranged between 1 and 156 months with a median of 17 months. According to HLH-2004 diagnostic criteria, hyperferritinemia was present in all tested patients, hypertriglyceridemia in 63.8%, hypofibrinogenemia in 47.6%, hemophagocytosis in 25%, and elevated soluble CD25 in 84.6%. Seventeen patients (31.5%) fulfilled greater than or equal to 5 HLH-2004 diagnostic criteria, although only 13 (24.1%) patients were fully investigated. The Hscore was higher in patients meeting HLH criteria (P<0.001), but the Pediatric Logistic Organ Dysfunction 2 score was lower (P=0.08). The overall mortality was 63%; more patients (76.5%) died in the HLH group (P=0.16) with a shorter median PICU stay (P=0.03). Conclusion The present study reported the clinical characteristics of children with clinically suspected HLH in a central PICU from a low–middle-income country. HLH was not adequately investigated in PICU patients, and the mortality rate was high. Raising awareness about HLH among PICU physicians is mandatory to minimize missing the diagnosis of HLH.