Hemophagocytic lymphohistiocytosis: an update in diagnostics, criteria, and treatment considerations

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory state in adult and pediatric patients, with associated severe morbidity and mortality. Here, we provide an updated overview of HLH, associated triggers, diagnostic tools and criteria, as well as treatment considerations.

Hemophagocytosis lymphohistiocytosis, a state of severe inflammation and immune overactivation, can be life threatening with significant risk of morbidity and mortality. Diagnostic criteria initially used remain valid to this day, while newer laboratory measurements can be informative and helpful in identifying patients with this diagnosis, such as CXCL9, IL-18, and other serum cytokines. Initially thought to occur only in patients with inborn errors of immunity or malignancy, HLH is recognized as a spectrum of inflammation, occurring in healthy individuals in response to common infections. With this realization comes a pressing need for earlier consideration, identification, and treatment initiation to prevent severe or fatal outcomes.

Recent insights into the diagnosis of HLH have led to earlier identification, associated triggers and laboratory criteria, with the goal of decreasing delays in time to treatment and improved outcomes.