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

HLH Newsfeed

pubmed: histiocytosis

NCBI: db=pubmed; Term=histiocytosis

Clinical implications of oncogenic mutations in pulmonary Langerhans cell histiocytosis.

Curr Opin Pulm Med. 2018 Feb 20;:

Authors: Brown NA, Elenitoba-Johnson KSJ

PURPOSE OF REVIEW: Langerhans cell histiocytosis (LCH) is a neoplasm of dendritic cells with a wide clinical spectrum. Localized pulmonary LCH occurs in young adults with a history of smoking and can either resolve spontaneously or lead to progressive decline in pulmonary function. Young children can also present with localized disease - frequently bone or skin - or with multifocal or multisystem disease. Clinical outcomes in these patients also vary widely, ranging from spontaneous resolution to multiorgan failure and death. This review describes recent developments in our understanding of the underlying pathogenesis of LCH and how these discoveries and other research are affecting how the disease is classified, treated and monitored.
RECENT FINDINGS: Somatic mutations resulting in activation of the mitogen-activated protein kinase (MAPK) pathway were recently identified as a key pathogenetic mechanism in both pediatric and pulmonary LCH.
SUMMARY: Knowledge of underlying pathogenetic mechanisms of LCH transforming how this disease and other histocytic/dendritic disorders are classified, treated and monitored.

PMID: 29470255 [PubMed - as supplied by publisher]

Indeterminate cell histiocytosis in a Chinese patient with florid and extensive nodular lesions and mixed intermediate cell and macrophage-monocyte bilineage.

J Cutan Pathol. 2018 Feb 22;:

Authors: Chen Q, Lee JS, Liang WM, Chan MF, Pujol RM, Luis R, Tan SH

Indeterminate cell histiocytosis (ICH) is an extremely rare cutaneous neoplastic disorder. It has the immunophenotypic features of both Langerhans and non-Langerhans cell histiocytosis. We report here a case of a healthy young Chinese woman who presented with disfiguring thick, infiltrated cutaneous nodules on the face, trunk and extremities which appeared progressively over a period of 4 years. No systemic involvement has been detected so far. Results of a skin biopsy showed diffuse dermal infiltration of histiocytoid cells with indented nuclei and positive staining for S100 and CD1a and negativity for CD207 (langerin). Admixed within were some CD68-positive foamy histiocytes and multinucleated giant cells with focal positivity for CD163. Though the clinical presentation is more typical of progressive nodular histiocytosis, the histology and immunoprofile is consistent with ICH. Our report adds to the limited case reports in the current literature of ICH in the Chinese population.

PMID: 29469188 [PubMed - as supplied by publisher]

Related Articles

The multiple faces of Langerhans cell histiocytosis in childhood: A gentle reminder.

Mol Clin Oncol. 2018 Mar;8(3):489-492

Authors: Papadopoulou M, Panagopoulou P, Papadopoulou A, Hatzipantelis E, Efstratiou I, Galli-Tsinopoulou A, Papadopoulou-Alataki E

Langerhans cell histiocytosis (LCH) is a rare hematologic disorder that results from the clonal multiplication and accumulation of immature dendritic Langerhans cells. Its reported incidence rate varies, but is considered to be 2.6-8.9 per million children who are <15 years of age each year. It may affect any system or organ. The present study reported 4 pediatric LCH cases in order to highlight the heterogeneity of the initial presentation, and the pitfalls that may mislead clinicians and delay diagnosis. The clinical features, as well as the pathognomonic imaging, pathology findings and treatment options were presented. LCH may be rare, but it should always be included in the differential diagnosis of persistent eczema, unexplained skin lesions, diabetes insipidus and persistent bone pain, among others. While the debate on pathogenesis and treatment is ongoing, high index of suspicion among pediatricians, pediatric oncologists and other specialists (pathologists, dermatologists, orthopaedic surgeons, general practitioners or family physicians) is essential for early diagnosis, and optimal outcome.

PMID: 29468064 [PubMed]

Related Articles

Efficacy of the MEK inhibitor cobimetinib for wild-type BRAF Erdheim-Chester disease.

Br J Haematol. 2018 01;180(1):150-153

Authors: Cohen Aubart F, Emile JF, Maksud P, Galanaud D, Cluzel P, Benameur N, Aumaitre O, Amoura Z, Haroche J

PMID: 27711968 [PubMed - indexed for MEDLINE]

Related Articles

Cholesterol-dependent increases in glucosylceramide synthase activity in Niemann-Pick disease type C model cells: Abnormal trafficking of endogenously formed ceramide metabolites by inhibition of the enzyme.

Neuropharmacology. 2016 Nov;110(Pt A):458-469

Authors: Hashimoto N, Matsumoto I, Takahashi H, Ashikawa H, Nakamura H, Murayama T

Sphingolipids such as sphingomyelin and glycosphingolipids (GSLs) derived from glucosylceramide (GlcCer), in addition to cholesterol, accumulate in cells/neurons in Niemann-Pick disease type C (NPC). The activities of acid sphingomyelinase and lysosomal glucocerebrosidase (GCase), which degrade sphingomyelin and GlcCer, respectively, are down-regulated in NPC cells, however, changes in GlcCer synthase activity have not yet been elucidated. We herein demonstrated for the first time that GlcCer synthase activity for the fluorescent ceramide, 4-nitrobenzo-2-oxa-1,3-diazole-labeled C6-ceramide (NBD-ceramide) increased in intact NPC1((-/-)) cells and cell lysates without affecting the protein levels. In NBD-ceramide-labeled NPC1((-/-)) cells, NBD-fluorescence preferentially accumulated in the Golgi complex and vesicular specks in the cytoplasm 40 and 150 min, respectively, after labeling, while a treatment for 48 h with the GlcCer synthase inhibitors, N-butyldeoxynojirimycin (NB-DNJ) and 1-phenyl-2-palmitoylamino-3-morpholino-1-propanol, accelerated the appearance of vesicular specks emitting NBD-fluorescence within 40 min. The treatment of NPC1((-/-)) cells with NB-DNJ for 48 h additionally increased the levels of cholesterol, but not those of sphingomyelin. Increases in the activity of GlcCer synthase and formation of vesicular specks emitting NBD-fluorescence in NPC1((-/-)) cells were dependent on cholesterol. LacCer taken up by endocytosis, which accumulated in the Golgi complex in normal cells, accumulated in vesicular specks after 10 and 40 min in NPC1((-/-)) cells, and this response was not accelerated by the NB-DNJ treatment, but was restored by the depletion of cholesterol. The cellular roles for enhanced GlcCer synthesis and increased levels of cholesterol in the trafficking of NBD-ceramide metabolites in NPC1((-/-)) cells have been discussed.

PMID: 27539961 [PubMed - indexed for MEDLINE]

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