To explore the diagnostic characteristics of children with hemophagocytic lymphohistiocytosis (HLH) complicated with sepsis.

Between January 2016 and July 2020, clinical symptoms and laboratory test results of 37 children with HLH secondary to sepsis from the Pediatric Intensive Care Unit (PICU) of Guangdong Women and Children Hospital were collected retrospectively.

Fever (100.00%) was the most common clinical symptom in 37 children with sepsis complicated with HLH, the peak fever was over 38 ℃ followed by hepatomegalemia (32.43%), rash (32.43%), superficial lymphadenopathy (27.03%) and trisophysis (21.62%). All 37 children showed varying degrees of high levels of alanine aminotransferase, D-dimer, and serum ferritin in laboratory tests. The hemoglobin level and platelet count decreased in 29 cases (78.38%), the proportion of B lymphocytes increased in 23 cases (62.16%), the proportion of NK cells decreased in 24 cases (64.86%), and the aspartate aminotransferase increased in 34 cases (91.89%). In the bone marrow, hemophagocytic cells were discovered. Pathogen detection was positive in 29 cases (78.38%), with EB virus having the highest detection rate (48.65%), and candida albicans being the main fungus (18.92%). The respiratory tract was the most common site of infection (37.84%). After the treatment, 15 patients recovered, 8 were transferred to another hospital, 12 discontinued their treatment , and 2 died.

Children with sepsis complicated by HLH have a wide range of clinical manifestations. Methemoglobinemia and/or EB virus infection are common in laboratory and pathogen detection. Early diagnosis plays an important role in saving the lives of children.