Overview of Histiocytic Syndromes

By Jeffrey M. Lipton, MD, PhD, Schneider Children’s Hospital;Albert Einstein College of Medicine

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Histiocytic Syndromes
Overview of Histiocytic Syndromes
Langerhans Cell Histiocytosis
Hemophagocytic Lymphohistiocytosis (HLH)
Rosai-Dorfman Disease

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

Category	Usual Disorders*	Examples or Description
Histiocytic disorders of varied biologic behavior
Dendritic cell–related	Langerhans cell histiocytosis	Includes the disorders formerly called eosinophilic granuloma, Letterer-Siwe disease, and Hand-Schüller-Christian disease
Macrophage-related	Primary hemophagocytic syndromes	Familial Sporadic
	Secondary hemophagocytic syndromes	Infection Cancer Autoimmune disorders
	Rosai-Dorfman disease	Also called sinus histiocytosis with massive lymphadenopathy
Malignant histiocytic disorders
Leukemias	Acute monocytic and myelomonocytic leukemia	—
	Chronic myelomonocytic leukemia (CMML)	Adult 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.