Hemophagocytic Lymphohistiocytosis (HLH) By Jeffrey M Lipton, MD, PhD, Zucker School of Medicine at Hofstra / Northwell; Carolyn Fein Levy, MD, Donald and Barbara Zucker School of Medicine at Hofstra / Northwell Reviewed / Revised Dec 2021 | Modified Sep 2022 View Patient Education Symptoms and Signs Diagnosis Treatment Key Points More Information Hemophagocytic lymphohistiocytosis (HLH) is an uncommon disorder causing immune dysfunction in infants and young children.