Histiocytosis: MedlinePlus Medical Encyclopedia

P Histiocytosis is a general name for a group of disorders or "syndromes" that involve an abnormal increase in the number of specialized white blood cells that are called histiocytes.
P Recently, new knowledge about this family of diseases has led experts to develop new classifications. Five categories have been proposed:
- L group -- includes Langerhans cell histiocytosis
- C group -- includes non- Langerhans cell histiocytosis that involves the skin
- M group -- includes malignant histiocytosis
- R group -- includes Rosai-Dorfman disease
- H Group -- includes hemophagocytic lymphohistiocytosis
P This article focuses only on the L group, which includes Langerhans cell histiocytosis.

T Causes
P There has been debate as to whether Langerhans cell histiocytosis is an inflammatory, immune disorder, or a cancer-like condition. Recently, the era of genomics has helped show that Langerhans cell histiocytosis is likely due to acquired changes in the genes (mutations) in early white blood cells, which leads to abnormal behavior. The abnormal cells then increase in various parts of body including the bones, skin, lungs, and other areas.
P Langerhans cell histiocytosis is a rare disorder that can affect people of all ages. The highest rate is among children ages 5 to 10. Some forms of the disorder are genetic, which means they are inherited.
P Pulmonary histiocytosis X is a specific type of histiocytosis X that involves swelling of the small airways and small blood vessels in the lungs. This inflammation leads to lung stiffening and damage. It is most common in 30 to 40 year old adults, who most often smoke cigarettes. The cause is unknown.

T Symptoms
P Histiocytosis X often affects the whole body. A disease that affects the whole body is called a "systemic" disorder.
P Symptoms can vary between children and adults, but they may have some of the same symptoms. Tumors in weight-bearing bones, such as the legs or spine, may cause the bones to fracture without an obvious reason.
P Symptoms in children may include:
- Abdominal pain
- Bone pain (possibly)
- Delayed puberty
- Dizziness
- Ear drainage that continues long-term
- Eyes that appear to stick out more and more
- Irritability
- Failure to thrive
- Fever
- Frequent urination
- Headache
- Jaundice
- Limping
- Mental decline
- Rash
- Seborrheic dermatitis of the scalp
- Seizures
- Short stature
- Swollen lymph glands
- Thirst
- Vomiting
- Weight loss
P Note: Children over 5 years old often have only bone involvement.
P Symptoms in adults may include:
- Bone pain
- Chest pain
- Cough
- Fever
- General discomfort, uneasiness, or ill feeling
- Increased amount of urine
- Rash
- Shortness of breath
- Thirst and increased drinking of fluids
- Weight loss

T Exams and Tests
P There are no specific blood tests for Langerhans cell histiocytosis.The tumors produce a "punched-out" look on a bone x-ray. Specific tests vary, depending on the age of the person.
P Tests for children may include:
- Biopsy of skin to check for Langerhans cells
- Bone marrow biopsy to check for Langerhans cells
- Complete blood count (CBC)
- X-rays of all the bones in the body to find out how many bones are affected
- Test for a gene mutation in BRAF V600E
P Tests for adults may also include:
- Bronchoscopy with biopsy
- Chest x-ray
- Pulmonary function tests
P Langerhans cell histiocytosis is sometimes linked to cancer. CT scans and biopsy should be done to rule out possible cancer.

T Treatment
P Langerhans cell histiocytosis is such a rare disorder that information about the best possible treatment is limited. For this reason, people with the condition are encouraged to take part in a well-designed clinical trial.
P People with Langerhans cell histiocytosis involving only a single place such as bone or skin may be treated with local surgery. However, they will need close follow-up to look for disease spread.
P People with widespread Langerhans cell histiocytosis require medicines. In most cases, prednisone and vinblastine are the first drugs tried. Smoking may worsen the response to treatment and should be stopped.
P Other medicines or treatments may be used, depending on the outlook (prognosis) and response to the starting medicines. Such treatments may include:
- Cyclophosphamide
- Etoposide
- Methotrexate
- Vemurafenib, if the BRAF V600E mutation is found
- Stem cell transplantation
P Other treatments may include:
- Antibiotics to fight infections
- Breathing support (with a breathing machine)
- Hormone replacement therapy
- Physical therapy
- Special shampoos for scalp problems
- Supportive care (also called comfort care) to relieve symptoms

T Support Groups
P Histiocytosis Association www.histio.org

T Outlook (Prognosis)
P Langerhans cell histiocytosis affects many organs and can lead to death.
P About one half of those with pulmonary histiocytosis improve, while others have permanent loss of lung function over time.
P In very young people, the outlook depends on the specific histiocytosis and how severe it is. Some children can live a normal life with minimal disease involvement, while others do poorly. Young children, especially infants, are more likely to have bodywide symptoms that lead to death.

T Possible Complications
P Complications may include:
- Diffuse interstitial pulmonary fibrosis (deep lung tissues that become inflamed and then damaged) 
- Spontaneous collapsed lung
P Children may also develop:
- Anemia caused by spreading of the tumors to the bone marrow
- Diabetes insipidus (a rare form of diabetes) 
- Lung problems that lead to lung failure
- Problems with the pituitary gland that lead to growth failure

T When to Contact a Medical Professional
P Call your health care provider if you or your child has symptoms of this disorder. Go to the emergency room if shortness of breath or chest pain develops.

T Prevention
P Avoid smoking. Quitting smoking can improve the outcome in people with Langerhans cell histiocytosis that affects the lungs.
P There is no known prevention for the childhood forms of this disease.

T Alternative Names
P Langerhans cell histiocytosis; Eosinophilic granuloma

T Images
- Eosinophilic granuloma - x-ray of the skull
- Respiratory system

T References
P Emile J-F, Abla O, Fraitag S, et al. Revised classification of histiocytoses and neoplasms of the macrophage-dendritic cell lineages. Blood. 2016;127(22):2672-2681. PMID: 26966089. www.ncbi.nlm.nih.gov/pubmed/26966089.
P Haupt R, Minkov M, Astigarraga I, et al. Langerhans cell histiocytosis (LCH): guidelines for diagnosis, clinical work-up, and treatment for patients till the age of 18 years. Pediatr Blood Cancer. 2013;60(2):175-184. PMID: 23109216. www.ncbi.nlm.nih.gov/pubmed/23109216.
P Hyman DM, Puzanov I, Subbiah V, et al. Vemurafenib in multiple nonmelanoma cancers with BRAF V600 mutations. N Engl J Med. 2015;373(8):726-736. PMID: 26287849. www.ncbi.nlm.nih.gov/pubmed/26287849.
P Zinn DJ, Chakraborty R, Allen CE. Langerhans cell histiocytosis: emerging insights and clinical implications. Oncology. 2016;30(2):122-132, 139. PMID: 26888790. www.ncbi.nlm.nih.gov/pubmed/26888790.

T Review Date 6/9/2016
P Updated by: Gordon A. Starkebaum, MD, Professor of Medicine, Division of Rheumatology, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.

