CONTEMPORARY CLASSIFICATION OF HISTIOCYTIC DISORDERS

Pathologists and pediatric hematologist/oncologists of the World Healt h Organization's Committee on Histiocytic/Reticulum Cell Proliferation s and the Reclassification Working Group of the Histiocyte Society pre sent a classification of the histiocytic disorders that primarily affe ct children. Nosology, based on the lineage of lesional cells and biol ogical behavior, is related to the ontogeny of histiocytes (macrophage s and dendritic cells of the immune system). Dendritic cell-related di sorders of varied biological behavior are dominated by Langerhans cell histiocytosis, but separate secondary proliferations of dendritic cel ls must be differentiated. Juvenile xanthogranuloma represents a disor der of dermal dendrocytes, another dendritic cell of skin. The hemopha gocytic syndromes are the most common of the macrophage-related disord ers of varied biological behavior. Guidelines for distinguishing the e xceedingly rare malignant diseases of histiocytes from large cell lymp homas through the use of a battery of special studies are provided. (C ) 1997 Wiley-Liss, Inc.