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

Solitary extranodal Rosai-Dorfman disease of the mandible: an exceedingly rare presentation.

Autops Case Rep. 2018 Jul-Sep;8(3):e2018036

Authors: Hamza A, Zhang Z, Al-Khafaji B

Sinus histiocytosis with massive lymphadenopathy, generally known by the name of Rosai-Dorfman disease is a rare benign condition principally affecting cervical lymph nodes. Concurrent extra-nodal disease frequently occurs, however, solitary extra-nodal disease involving the mandible is exceedingly rare with less than five reported cases in the English literature. We describe a case of primary involvement of the mandible in a 27-year-old female, and discuss the differential diagnosis of this disease with other histiocytic lesions.

PMID: 30101140 [PubMed]

Related Articles

The H Syndrome: A Genodermatosis.

Cureus. 2018 Jun 08;10(6):e2763

Authors: Bhatti S, Jamil A, Siddiqui SH, Yaqoob U, Virk LN, Bhatti A

H syndrome (histiocytosis lymph adenopathy plus syndrome) is an autosomal recessive disorder caused by mutations in the SLC29A3 gene, encoding the human equilibrative nucleoside transporter (hENT3), characterized by cutaneous hyperpigmentation and hypertrichosis, hepatosplenomegaly, hearing loss, heart anomalies, hypogonadism, low height, hyperglycemia/insulin-dependent diabetes mellitus, and hallux valgus/flexion contractures. Exophthalmos, malabsorption, renal anomalies, flexion contractions of interphalangeal joints and hallux valgus, and lytic bone lesions, as well as osteosclerosis, are also seen. If these are lacking, the constellation of additional findings should raise suspicion for H syndrome. As most of the patients reported to date with H syndrome are from traditional, low-income populations, where consanguinity is common, it is highly important to develop a cheap and affordable technique for a mutation analysis. Two siblings presented to us, diagnosed as having insulin-dependent diabetes mellitus (IDDM) since the age of eight years and progressive flexion contracture of the small joints for seven-eight years. On examination, both had short stature. One also had bilateral cervical lymphadenopathy. The female had the Tanner stage of B3P3A2 M0 and the male had the Tanner stage of prepuberty. Laboratory workup, including antinuclear antibodies, rheumatoid factor, erythrocyte sedimentation rate, thyroid profile, and Celiac serology were negative. Genetic studies confirmed the diagnosis of H syndrome.

PMID: 30101042 [PubMed]

Related Articles

Intracranial Rosai-Dorfman disease involving the cavernous sinus: a case report and review of the literature.

World Neurosurg. 2018 Aug 09;:

Authors: Li Z, Zhou C, Chen G, Bao Y

BACKGROUND: Rosai-Dorfman disease (RDD), also called sinus histiocytosis with massive lymphadenopathy (SHML), is an idiopathic, non-neoplastic, lymphoproliferative disorder. Histologically, the disease is characterized by emperipolesis and S-100 immunoreactivity. RDD usually presents with massive painless cervical lymphadenopathy, only 5% affecting the central nervous system (CNS).
CASE DESCRIPTION: We here report on a 46-year-old female of isolated RDD of the left cavernous sinus with left facial numbness and weakness of left masticatory muscle. The patient was successfully treated by total resection without recurrence on the 65-month follow-up.
CONCLUSIONS: CNS RDD is a diagnostic challenge preoperatively depending on radiology. Immunohistochemical confirmation is indispensable to make a definite diagnosis. Total resection is still the most effective treatment so far. Adjuvant treatments like chemotherapy, radiotherapy and steroids could be administrated in cases of incomplete resection, recurrence or with multiple foci.

PMID: 30099183 [PubMed - as supplied by publisher]

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Morphological Distinction of Histiocytic Sarcoma from Other Tumor Types in Bernese Mountain Dogs and Flatcoated Retrievers.

In Vivo. 2018 Jan-Feb;32(1):7-17

Authors: Erich SA, Constantino-Casas F, Dobson JM, Teske E

BACKGROUND/AIM: Histiocytic sarcoma (HS) represents a group of malignant canine tumors to which Bernese Mountain Dogs (BMD) and Flatcoated Retrievers (FCR) are predisposed. The differential diagnosis for HS is broad, encompassing round cell tumors, sarcomas and other histiocytic diseases. The aim of this study was to establish morphological and immunohistochemical criteria for routine use on formalin-fixed, paraffin-embedded samples and cytological smears for the recognition and differentiation of canine HS and its subtypes.
MATERIALS AND METHODS: Retrospectively, tumor sections were reviewed from 449 BMD and 380 FCR with confirmed or suspected HS, other histiocytic conditions, or a disease of the differential diagnosis of HS.
RESULTS: In a large proportion of cases, 47.5% for histology and for 46.3% cytology, the initial diagnosis was changed after the revision process. A large variation in morphological features of HS was observed in this study, making the existence of several subtypes in dogs also very likely. Furthermore, the different percentage of morphological features between BMD and FCR indicates the different mixture of cell type origins resulting possibly from genetic or environmental differences at the onset of HS in those breeds.
CONCLUSION: This study stresses the value of a strictly applied and standardized scoring system for microscopic evaluation of tumor sections and smears, and the implementation of review and revision of pathological diagnoses.

PMID: 29275293 [PubMed - indexed for MEDLINE]

Related Articles

Clinical features and outcomes in secondary adult hemophagocytic lymphohistiocytosis.

QJM. 2018 Jan 01;111(1):23-31

Authors: Zhou M, Li L, Zhang Q, Ma S, Sun J, Zhu L, Lu D, Zhu J, Zhou D, Zheng Y, Yang X, Xie M, Zhu M, Ye X, Xie W

Background: Hemophagocytic lymphohistiocytosis (HLH) is a rare clinical syndrome characterized by an infrequent but immune-mediated life-threatening disease, with confusing clinical manifestations, rapidly deteriorating health, high morbidity and mortality and challenging diagnosis.
Aim: The purpose of this study was to improve the recognition and understanding of HLH.
Design: Retrospective observational cross-sectional study.
Methods: Data were collected for all cases of adult patients diagnosed with HLH in a large cohort managed at a single medical center from January 2011 to December 2015.
Results: The median age was 52 years (range 18-90 years) and 123 (60.0%) were male. Over 95% patients manifested fever, hyperferritinemia and elevated lactate dehydrogenase. Underlying triggers of HLH were as follows: 119 (58.0%) malignancies, 83 (40.5%) infections, 14 (6.8%) unknown triggers and 14 (6.8%) autoimmune disorders. The median overall survival was 55 days. And elderly patients (age ≥60 years) had a markedly worse survival compared with young patients (age <60 years) (median overall survival 24 days vs. 159 days, respectively; P <0.001). In a multivariable analysis, platelet <40 × 109/l (HR = 2.534; 95% CI 1.152-5.573; P = 0.021), PT prolonged >3 s (HR = 1.909; 95% CI 1.127-3.234; P = 0.016) and malignancy (HR = 1.614; 95% CI 1.008-2.582; P = 0.046) were correlated with poor survival.
Conclusion: HLH adult patients had very complex clinical manifestations as well as underlying diseases. Patients with PLT <40 ×109/l, PT prolonged >3 s and malignancy had inferior survival. It is of great importance to improve our understanding of this syndrome.

PMID: 29025045 [PubMed - indexed for MEDLINE]

Related Articles

Disseminated cutaneous Mycobacterium kansasii infection presenting with Rosai-Dorfman disease-like histological features in a patient carrying anti-interferon-γ autoantibodies.

J Dermatol. 2017 Dec;44(12):1396-1400

Authors: King YA, Hu CH, Lee YJ, Lin CF, Liu D, Wang KH

Typical cutaneous non-tuberculous mycobacteria (NTM) infections show a histopathology pattern of granulomas with admixed Langhans giant cells, and abscesses may be observed in acute lesions. Herein, we describe a patient carrying a high titer of autoantibodies to interferon (IFN)-γ with disseminated Mycobacterium kansasii infection presenting with emperipolesis and Rosai-Dorfman disease (RDD)-like histopathological features characterized by remarkable, large, pale-staining "RD cells", which were CD68 and S100 positive and CD1a negative. The patient was misdiagnosed with RDD initially, but exhibited a poor response to all interventions. A re-biopsy revealed Langhans-type multinucleated giant cells; multiple definite acid-fast bacilli were also found. M. kansasii was isolated from cultured tissues. Anti-NTM treatment was initiated. After treatment, all lesions resolved almost completely within the following month. High-titer anti-IFN-γ autoantibodies were detected during follow up, leading to the diagnosis of adult-onset immunodeficiency syndrome. In conclusion, patients carrying high-titer autoantibodies to IFN-γ who also have a disseminated cutaneous M. kansasii infection may present with RDD-like histopathological features, which may be a pitfall in the diagnosis of disseminated cutaneous NTM infections.

PMID: 28836691 [PubMed - indexed for MEDLINE]

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sQuiz your knowledge: Progressive loss of teeth and ulcerative genital lesions.

Eur J Dermatol. 2017 Apr 01;27(2):221-222

Authors: Qu H, Wang X, Wang M

PMID: 28400346 [PubMed - indexed for MEDLINE]

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