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

Oncogenic TRK fusions are amenable to inhibition in hematologic malignancies.

J Clin Invest. 2018 Jun 19;:

Authors: Taylor J, Pavlick D, Yoshimi A, Marcelus C, Chung SS, Hechtman JF, Benayed R, Cocco E, Durham BH, Bitner L, Inoue D, Chung YR, Mullaney K, Watts JM, Diamond EL, Albacker LA, Mughal TI, Ebata K, Tuch BB, Ku N, Scaltriti M, Roshal M, Arcila M, Ali S, Hyman DM, Park JH, Abdel-Wahab O

Abstract
Rearrangements involving the neurotrophic receptor kinase genes (NTRK1, NTRK2, and NTRK3; hereafter referred to as TRK) produce oncogenic fusions in a wide variety of cancers in adults and children. Although TRK fusions occur in <1% of all solid tumors, inhibition of TRK results in profound therapeutic responses resulting in breakthrough FDA-approval of the TRK inhibitor larotrectinib for adult and pediatric solid tumor patients regardless of histology. In contrast to solid tumors, the frequency of TRK fusions and clinical effects of targeting TRK in hematologic malignancies is unknown. Here, through an evaluation for TRK fusions across > 7,000 patients with hematologic malignancies, we identified TRK fusions in acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), histiocytosis, multiple myeloma and dendritic cell neoplasms. Although TRK fusions occurred in only 0.1% of patients (8 out of 7,311 patients), they conferred responsiveness to TRK inhibition in vitro and in vivo in a patient-derived xenograft and a corresponding AML patient with ETV6-NTRK2 fusion. These data identify that despite their individual rarity, collectively TRK fusions are present in a wide variety of hematologic malignancies and predict clinically significant therapeutic responses to TRK inhibition.

PMID: 29920189 [PubMed - as supplied by publisher]

Related Articles

PDQ Cancer Information Summaries

Book. 2002

Authors:

Abstract
This PDQ cancer information summary has current information about the treatment of childhood and adult Langerhans cell histiocytosis. It is meant to inform and help patients, families, and caregivers. It does not give formal guidelines or recommendations for making decisions about health care. Editorial Boards write the PDQ cancer information summaries and keep them up to date. These Boards are made up of experts in cancer treatment and other specialties related to cancer. The summaries are reviewed regularly and changes are made when there is new information. The date on each summary ("Date Last Modified") is the date of the most recent change. The information in this patient summary was taken from the health professional version, which is reviewed regularly and updated as needed, by the PDQ Pediatric Treatment Editorial Board.


PMID: 26389196

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