Overview of Histiocytic Disorders 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 Topic Resources Histiocytic Disorders The histiocytic disorders are clinically heterogeneous disorders that result from an abnormal proliferation of histiocytes that are either Dendritic cells (antigen-presenting cells) Monocyte-macrophages (antigen-processing cells) Classifying histiocytic disorders is difficult (see table Histiocytic Disorders) and has changed over time as an understanding of the biology of these cells has evolved (1).