How can an internal medicine specialist save a patient with hemophagocytic lymphohistiocytosis (HLH)?

Hemophagocytic lymphohistiocytosis (HLH; also, hemophagocytic syndrome) occurs when an inflammatory reaction cannot stop on its own but continues to self-accelerate with positive feedback loops. If not interrupted, this pathomechanism leads to death. HLH in adults is usually diagnosed based on the HLH-2004 criteria, but its confirmation should not stop the diagnostic process. Finding the triggering factor (especially malignancy) is of utmost importance. Treatment strongly depends on the established trigger and it is often based on the etoposide HLH-94 protocol (adjusted for adults). Diagnostic workup should not unnecessarily delay the treatment since patients in severe or quickly deteriorating clinical condition require its fast initiation. Considering the progressive nature of HLH, time is extremely important. Prompt diagnosis and treatment, frequently made by an internal medicine specialist, is life-saving. The aim of this review is to raise HLH awareness among internal medicine specialists and to provide advice on HLH management tailored for this group of physicians. Suggested approach is based on the latest recommendations by the Histiocyte Society and include novel insights from the authors' experience.