New blood markers have been linked to the prognosis of children younger than 14 with hemophagocytic lymphohistiocytosis (HLH), a study reports.
The study, “Comparison between clinical features and prognosis of malignancy- and non-malignancy–associated pediatric hemophagocytic lymphohistiocytosis,” was published in the journal BMC Pediatrics.
HLH is the result of an imbalance in the immune system that causes the body’s immune cells to migrate to internal organs, leading to inflammation in the tissues.
HLH can be classified as primary HLH, when it is caused by a faulty gene, or as secondary HLH when it is caused by non-genetic factors.
Secondary HLH can be non-malignant when it is triggered by certain medications, a severe microbial infection, or an immune or rheumatologic disorder. Secondary HLH is called malignant when it develops in connection with cancer, as in the case of leukemia or Hodgkin’s lymphoma.
However, “the differences between the clinical characteristics and survival time in malignancy- and non-malignancy–associated secondary hemophagocytic lymphohistiocytosis (HLH) are unclear,” the researchers wrote.
To address this question, researchers in China looked at survival expectancy, clinical characteristics, and the presence of prognostic blood factors in children with malignancy- and non-malignancy-associated HLH.
They analyzed data from 91 children, younger than 14 years, with secondary HLH, who had been seen at the Affiliated Hospital of Qingdao University Pediatric Department, China, between January 2005 and October 2016. The malignancy-associated HLH group included 22 children, and the non-malignancy-associated HLH group included 69 children.
They found that children with non-malignancy-associated HLH were able to survive an average of nine months longer than children with malignancy-associated HLH — a mean survival time of 26 months versus 35.03 months. However, a statistical analysis revealed that this difference was not significant.
Regarding prognostic factors, the team found that in children with malignancy-associated HLH, there were some blood factors that could suggest a worse prognosis. These include: a low number of platelets (blood cells involved in coagulation), and a high disseminated intravascular coagulation (DIC) score — which occurs when platelets form blood clots and block small blood vessels.
The team also found a poorer prognosis in both groups when children had low blood levels of hemoglobin (a protein in red blood cells), and albumin (the main protein in blood that regulates blood volume).
A high level of hemophagocytosis was also a factor that contributed to a worse prognosis in both groups of children. Hemophagocytosis — the absorption of blood cells and platelets by immune cells called phagocytes — in the bone marrow is a common characteristic of HLH.
Based on the results, the team concluded that “patients with non-malignancy–associated HLH do not have better survival, although their prognosis is relatively better in clinical practice. A higher DIC score at diagnosis, and lower albumin, [hemoglobin], and [platelet count] levels are negative prognostic factors in malignancy-associated HLH.”
However, “prospective studies with a randomized controlled design, and involving large cohorts of children, are warranted to evaluate the exact incidence, clinical features, and appropriate treatment protocols of this association [malignancy-associated HLH with low platelets and high DIC score],” the researchers said.
“Mutation analysis, effective diagnostic criteria, and new targeted treatments for HLH for improving the survival rate of patients with malignancy-associated HLH are necessary,” they added.