Specialty Hematology 

In medicine, histiocytosis is an excessive number of histiocytes[1] (tissue macrophages), and the term is also often used to refer to a group of rare diseases which share this sign as a characteristic. Occasionally and confusingly, the term "histiocytosis" is sometimes used to refer to individual diseases.

According to the Histiocytosis Association of America, 1 in 200,000 children in the United States are born with histiocytosis each year.[2] HAA also states that most of the people diagnosed with histiocytosis are children under the age of 10, although the disease can afflict adults. The University of California, San Francisco, states that the disease usually occurs from birth to age 15.[3]

Histiocytosis (and malignant histiocytosis) are both important in veterinary as well as human pathology.


Types of LCH have also been known as "eosinophilic granuloma", "Hand-Schuller-Christian disease", "Letterer-Siwe disease", and "histiocytosis X". (See the article Langerhans cell histiocytosis for details).

Alternatively, histiocytoses may be divided into the following groups:[4]:714–724

Lymphohistiocytosis is "a widespread infiltrate of non-malignant lymphocytes and macrophages, involving principally the liver, spleen and central nervous system and associated with a severe lymphoid atrophy."[5]



There are competing systems for classifying histiocytoses. According to the 1999 classification proposed by the World Health Organization, they can be divided into three categories.[6][7] However, the classifications in ICD10 and MeSH are slightly different, as shown below:

Langerhans cell histiocytosis (LCH)ID76.0Langerhans-cell histiocytosis
Juvenile xanthogranuloma (JXG)IID76.3non-Langerhans-cell histiocytosis
Hemophagocytic lymphohistiocytosis (HLH)IID76.1non-Langerhans-cell histiocytosis
Niemann–Pick diseaseIIE75.2non-Langerhans-cell histiocytosis
Sea-blue histiocytosisII-non-Langerhans-cell histiocytosis
Acute monocytic leukemiaIIIC93.0malignant histiocytic disorders
Malignant histiocytosisIIIC96.1malignant histiocytic disorders
Erdheim–Chester diseaseIIC96.1malignant histiocytic disorders



Patients and families can gain support and educational materials from the Histiocytosis Association, or the Histiocytosis Research Trust. Information concerning histiocytosis and clinicians located in European countries may be found in many languages at the web portal of Euro Histio Net (EHN). This is a project funded by the European Union, co-ordinated by Dr. Jean Donadieu, APHP, Paris, FRANCE. Additional information about Erdheim-Chester Disease can be obtained from the ECD Global Alliance.

The Histiocyte Society, a nonprofit organization, is a group of more than 200 physicians and scientists from around the world committed to improving the lives of patients with histiocytic disorders by conducting clinical and laboratory research into the causes and treatment of this disease. The Society has instituted several clinical trials and treatment plans.


  1. Histiocytosis at eMedicine Dictionary
  2. Disease information at the Histiocytosis Association of America
  3. Histiocytosis - Signs and Symptoms
  4. James, William D.; Berger, Timothy G.; et al. (2006). Andrews' Diseases of the Skin: clinical Dermatology. Saunders Elsevier. ISBN 0-7216-2921-0.
  5. Goldberg, J; Nezelof, C (1986), "Lymphohistiocytosis: a multi-factorial syndrome of macrophagic activation clinico-pathological study of 38 cases", Hematol Oncol, 4 (4): 275–289, PMID 3557322.
  6. Harris N, Jaffe E, Diebold J, Flandrin G, Muller-Hermelink H, Vardiman J, Lister T, Bloomfield C (1999). "The World Health Organization classification of neoplastic diseases of the hematopoietic and lymphoid tissues. Report of the Clinical Advisory Committee meeting, Airlie House, Virginia, November, 1997". Ann Oncol. 10 (12): 1419–32. doi:10.1023/A:1008375931236. PMID 10643532.
  7. Histiocytosis at eMedicine
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