Iatrogenic HLH.

Hemophagocytic lymphohistiocytosis (HLH) can be categorized as either primary (familial, generally occurring in infants) or secondary (sHLH, occurring at any age in association with a variety of conditions) and is mainly triggered by infections, autoimmune diseases, and malignant conditions. Our understanding of the pathophysiology of sHLH is still evolving, and among the causes and associations with the syndrome, those putatively associated with iatrogenic causes remain among the most poorly understood due to the rarity of these entities and the multiple confounders so often present in the patients in whom they are reported. Herein, we present a review of the literature to describe the diagnostic and therapeutic challenges of sHLH associated with iatrogenic causes and discuss some of the challenges and future directions in our efforts to better understand these complex conditions for the advancement of patient outcomes.