The histiocytic syndromes are clinically heterogeneous disorders that result from an abnormal proliferation of histiocytes—either monocyte-macrophages (antigen-processing cells) or dendritic cells (antigen-presenting cells). Classifying these disorders is difficult (see Some Histiocytic Syndromes) and has changed over time as an understanding of the biology of these cells has evolved. There are other rare histiocytic disorders such as Erdheim-Chester disease, juvenile xanthogranuloma, and others.
Some Histiocytic Syndromes
Examples or Description
Histiocytic disorders of varied biologic behavior
Langerhans cell histiocytosis
Includes the disorders formerly called eosinophilic granuloma, Letterer-Siwe disease, and Hand-Schüller-Christian disease
Primary hemophagocytic syndromes
Secondary hemophagocytic syndromes
Also called sinus histiocytosis with massive lymphadenopathy
Malignant histiocytic disorders
Acute monocytic and myelomonocytic leukemia
Chronic myelomonocytic leukemia (CMML)
Childhood CMML (juvenile myelomonocytic leukemia)
*Other, rare disorders exist in each category.
Adapted from Komp DM, Perry MC: Introduction: The histiocytic syndromes.
Seminars in Oncology 18:1, 1991 and Favara BE, Feller AC, Pauli M, eds.: Contemporary classification of histiocytic disorders.
Medical and Pediatric Oncology 29:157, 1997.
Last full review/revision June 2013 by Jeffrey M. Lipton, MD, PhD