What is Histiocytosis
What is Histiocytosis?
Histiocytic Disorders and Rare Diseases – together we will find a cure!

Histiocytosis is an umbrella term applied to a group of rare diseases, characterised by increased numbers of white blood cells called histiocytes in the blood and tissues. In all forms of histiocytosis, these cells, which are part of the protective immune system, begin to attack the body, targeting many organs of the body including the bone marrow, liver, spleen, lungs, skin, bone and brain. The prognosis for patients varies greatly depending on the form of histiocytosis.

There are two main groups.
The first group is called a dendritic cell disorder, and the most common disease in this group is Langerhans Cell Histiocytosis (LCH) previously known as Histiocytosis X. Also included in this group are more rare diseases, juvenile xanthogranuloma (JXG) and Erdheim-Chester Disease (ECD).

Langerhans Cell Histiocytosis, LCH for short, histiocytes called Langerhans cells, which are normally found in the skin, may spread to many organs and damage them, so that the symptoms vary depending on which organs are affected, but skin rashes, destruction of bone, breathing problems and damage to the brain are common.

LCH occurs in children, often during infancy but also in adults. It is usually a chronic disease and may cause severe disabilities due to brain damage. The diagnosis is made by microscopic examination of a tissue specimen obtained by biopsy. The prognosis depends very much on the extent of disease and organs affected, which can be assessed by imaging studies. LCH is thought to be caused by alterations in the DNA of Langerhans cells.

The second group is called a macrophage cell disorder, and includes primarily Haemophagocytic Lymphohistiocytosis (HLH) and Rosai-Dorfman Disease (RD).

How to explain Histiocytosis

How to explain Histiocytosis

Haemophagocytic Lymphohistiocytosis HLH for short. In this disease a virus infection triggers another type of histiocyte, the macrophage, to become over active and attack the body. Red blood cells and other white blood cells are engulfed and destroyed by the macrophages, so that the patient is unable to fight infections.


Patients therefore suffer from high fevers, may become anaemic and often have skin rashes, as well as symptoms due to the infecting virus. HLH is an acute and life threatening disease. It frequently occurs in childhood but may occur at any age.

Diagnosis depends on detection of the infecting organism and demonstration of macrophages engulfing other cells as well as other abnormalities of white blood cells, usually in sample of bone marrow. In familial forms of HLH, abnormal genes, which alter white blood cell function, are passed from the parents to children.

Rarer Forms - there are other even rarer forms of histocytosis related to both LCH and HLH and very rarely malignant histiocytosis occurs, which is a leukaemia-like disease of histiocytes.

Please be advised that all the information you read here is not a replacement for the advice you will get from your consultant and their team.

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Frequently Asked Questions

Histiocytic Disorders and Rare Diseases

Why are all of these diseases with different names considered to be related to each other?
All of the diseases are caused by the over-production of white blood cells called histiocytes. Their different classifications depend on the type of histiocyte involved.

Where can I find reliable information about histiocytosis?
Histiocytosis UK online community provides a number of informational documents and articles, as well as links to medical articles about the histiocytic disorders. While the Internet does provide a significant volume of information about histiocytic disorders, some of this information is not accurate. It is important to look for documents that are current, are free of grammatical and spelling errors, appear to be objective, are free of advertisements, and clearly state their sources.

How to explain Histiocytosis

How to explain Histiocytosis

How can I explain histiocytosis to family and friends?
Histiocytosis is a rare disease that is caused by the over-production of a type of white cell that can lead to organ damage and the formation of tumors. The Histiocytosis UK FAQ pages are also a great way to help explain these complicated diseases to family and friends.


What is Rare Disease?

  • A rare disease is defined by the European Union as one that affects less than 5 in 10,000 of the general population.
  • There are between 6,000 and 8,000 known rare diseases.
  • Around five new rare diseases are described in medical literature each week.
  • 1 in 17 people, or 7% of the population, will be affected by a rare disease at some point in their lives.
  • This equates to approximately 3.5 million people in the UK and 30 million people across Europe.
  • In the UK, a single rare disease may affect up to about 30,000 people.
  • The vast majority of rare diseases will affect far fewer than this – some will affect only a handful, or even a single person in the whole of the UK.
  • 80% of rare diseases have a genetic component.
  • Often rare diseases are chronic and life-threatening.
  • Rare diseases can be single gene, multifactorial, chromosomal or non-genetic.
  • 75% of rare diseases affect children, and 30% of rare disease patients die before their fifth birthday.

Where can I learn more about rare diseases in general?
Rare Disease UK (RDUK) is the national alliance for people with rare diseases and all who support them. www.raredisease.org.uk.
Orphanet – Database/information about rare diseases with translation available in numerous languages. http://www.ojrd.com
Please be advised that all the information you read here is not a replacement for the advice you will get from your consultant and their team.

Help ensure that we can continue to bring you this vital informational material, make a donation today

LCH Newsfeed

pubmed: histiocytosis

NCBI: db=pubmed; Term=histiocytosis

Related Articles

Multiple Juvenile Xanthogranuloma of the Eyelids.

Ocul Oncol Pathol. 2018 Sep;4(2):73-78

Authors: Mori H, Nakamichi Y, Takahashi K

Juvenile xanthogranuloma (JXG) is a rare and benign tumor in infants. A solitary lesion on the eyelid has been reported in patients with JXG. We report a 15-year-old boy with multiple involvement of JXG on both eyelids. A mass on the left inner canthus was resected because of disturbance of the visual field and a risk of malignancy in terms of central ulceration in the lesion. The mass was examined by light microscopy. The mass had Touton giant cells with a wreath of nuclei surrounded by foamy histiocytes. No malignancy was observed. The mass showed no recurrence after resection.

PMID: 30320084 [PubMed]

Icon for Wolters Kluwer Related Articles

Fatal case of hemophagocytic lymphohistiocytosis associated with group B streptococcus sepsis: A case report.

Medicine (Baltimore). 2018 Oct;97(40):e12210

Authors: Choi YB, Yi DY

RATIONALE: Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease characterized by an excessive systemic inflammatory response. HLH is classified as primary or secondary, where the latter may occur in association with many infections. However, no case of HLH has been previously associated with group b streptococcus (GBS) sepsis.
PATIENT CONCERNS: We present a fatal case of HLH in a 5-year-old girl with GBS sepsis.
DIAGNOSIS: The present patient met 5 of the HLH criteria: fever, splenomegaly, bicytopenia, hypertriglyceridemia and/or hypofibrinogenemia, and hyperferritinemia. GBS was identified in 2 sets of peripheral blood bacterial cultures.
INTERVENTIONS: Empirical antibiotics, inotropes, and immunoglobulins were administered.
OUTCOMES: The clinical course of the patient was fulminant and the patient died of septic shock 10 hours after admission to the hospital.
LESSONS: We suggest GBS infection can cause HLH and early awareness of HLH associated with GBS infection and proper effective treatment are necessary to reduce mortality.

PMID: 30290591 [PubMed - indexed for MEDLINE]

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Immunohistochemical Labeling of Multiple Myeloma Oncogene 1/Interferon Regulatory Factor 4 (MUM1/IRF-4) in Canine Cutaneous Histiocytoma.

Vet Pathol. 2018 07;55(4):517-520

Authors: Stilwell JM, Rissi DR

Multiple myeloma oncogene 1/interferon regulatory factor 4 (MUM1/IRF-4) immunohistochemistry (IHC) is mainly used for diagnostic confirmation of plasma cell tumors (PCTs) in dogs and cats. This article describes MUM1/IRF-4 IHC expression in 20 cases of canine cutaneous histiocytoma (CH) and compares it with 10 cutaneous or mucocutaneous PCTs and 5 cutaneous histiocytic sarcomas (HSs) submitted to the same IHC protocol. All histiocytomas had strong nuclear and variable cytoplasmic immunolabeling for MUM1/IRF-4, whereas all PCTs had strong nuclear and moderate cytoplasmic immunolabeling for MUM1/IRF-4. No MUM1/IRF-4 immunolabeling was detected in the HSs. Although not typically a diagnostic challenge, MUM1/IRF-4 expression may have to be used with caution or in conjunction with additional immunomarkers to differentiate among poorly differentiated round cell tumors, especially when a histiocytic or plasma cell origin is suspected.

PMID: 29444632 [PubMed - indexed for MEDLINE]

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Xanthoma disseminatum.

Lancet. 2018 01 20;391(10117):251

Authors: Gong HZ, Zheng HY, Li J

PMID: 29031846 [PubMed - indexed for MEDLINE]

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A reply to the letter to the editor by Nima Derakhshan and Mahsa Roshanfarzad with regard to the paper "Pandora's box: eosinophilic granuloma at the cerebellopontine angle-should we open it?"

Childs Nerv Syst. 2017 09;33(9):1427

Authors: Öğrenci A, Ekşi MŞ

PMID: 28717831 [PubMed - indexed for MEDLINE]

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Cerebello-pontine angle eosinophilic granuloma; a reappraisal in the management of intracranial eosinophilic granuloma.

Childs Nerv Syst. 2017 09;33(9):1425-1426

Authors: Derakhshan N, Roshanfarzad M

PMID: 28646263 [PubMed - indexed for MEDLINE]

Related Articles

[Hemophagocytic syndrome associated to hepatitis].

Rev Alerg Mex. 2016 Jan-Mar;63(1):91-4

Authors: Sandoval-Ramírez E, Camacho-Meza I, Eduardo-Solís N, Plascencia-Tabares O, Navarro-Olivos E, Ortiz-Aldana FI

Hemophagocytic syndrome is characterized by increased proliferation and activation of antigen presenting cells (histiocytes) in bone marrow and other organs of the reticuloendothelial system as well as CD8+ T cells that threatens life of patients. The predominant clinical manifestations such as fever, cytopenia, hepatitis, coagulopathy, neurological symptoms and multiple organ failure are related to systemic inflammation. We report the case of an infant who started with jaundice, abdominal pain, vomiting and malaise, at admission, hepatomegaly, splenomegaly and biochemically with features suggestive of hepatocellular inflammation and progressive cholestasis with poor outcome, it was added persistent fever, seizures, anemia, thrombocytopenia, leukopenia, elevated ferritin and hypertriglyceridemia integrating hemophagocytic syndrome with fatal outcome despite immunosuppressive therapy.

PMID: 26943833 [PubMed - indexed for MEDLINE]

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