LCH in Children
Langerhans cell histiocytosis (LCH) is the most common of the histiocytic disorders and occurs when the body accumulates too many immature Langerhans cells, a subset of the larger family of cells known as histiocytes. Langerhans cells are a type of white blood cell that normally help the body fight infection. In LCH, too many Langerhans cells are produced and build up in certain parts of the body where they can form tumors or damage organs. The cause of this disease is unknown, although many possibilities have been explored, including viruses, exposure to toxins in the environment, family history and geography. Most data support the concept that LCH is a diverse disease characterized by a clonal growth of immature Langerhans cells that appear to have mutations of BRAF in about half the cases. LCH is not caused by a known infection. It is not contagious, nor is it believed to be inherited. Scientific discussions on the definition of LCH continue to be debated in terms of its classification as either an immune dysfunction or a rare cancer (neoplastic and malignant or not malignant). There remain differing opinions among experts as to whether it is definitively a cancer or not.
Histiocytosis was first described in the medical literature in the mid to late 1800s. Through the years, it has been known by various names, such as histiocytosis X, eosinophilic granuloma, Letterer-Siwe disease, Hashimoto-Pritzker disease, and Hand-Schüller-Christian syndrome. In 1973, the name Langerhans cell histiocytosis (LCH) was introduced. This name was agreed upon to recognize the central role of the Langerhans cell.
LCH is believed to occur in 1:200,000 children, but any age group can be affected, from infancy through adulthood. In newborns and very young infants, it occurs in 1-2 per million. It is, however, believed to be under-diagnosed, since some patients may have no symptoms, while others have symptoms that are mistaken for injury or other conditions. It occurs most often between the ages of 1-3 years and may appear as a single lesion or can affect many body systems, such as skin, bone, lymph glands, liver, lung, spleen, brain, pituitary gland and bone marrow.
Information has been collected in various studies which show that bone involvement occurs in approximately 78% of patients with LCH and often includes the skull (49%), hip/pelvic bone (23%), upper leg bone (17%) and ribs (8%). Skin LCH is seen in as many as 50% of patients. Lung lesions are seen in 20% to 40% of patients, while 30% of patients have lymph node involvement.
Symptoms depend on the location and severity of involvement. It is usually diagnosed with a tissue biopsy, in addition to other testing, such as x-rays and blood studies. A biopsy of an involved site is necessary to make a definitive diagnosis.
While some limited cases of histiocytosis may not require treatment, for patients with more extensive disease, chemotherapy may be necessary. Hematologists and oncologists, who treat cancer, also treat children with Langerhans cell histiocytosis.
Most patients with LCH will survive this disease. LCH in the skin, bones, lymph nodes or pituitary gland usually gets better with treatment and is called “low-risk.” Some patients have involvement in the spleen, liver, bone marrow, lung and skeleton. This is called “high-risk disease” and may be more difficult to treat. Some patients may develop long-term side effects such as diabetes insipidus, stunted growth, loss of teeth, bone defects, hearing loss, or neurologic problems; while other patients remain without side effects. In a minority of cases, the disease can be life-threatening.
Certain factors affect the chance of recovery and options for treatment. These factors include the extent of the disease, whether “risk organs” (liver, spleen, lung, bone marrow) are involved, and how quickly the disease responds to initial treatment.
Patients with LCH should usually have long term follow-up care to detect late complications of the disease or treatment. These may include problems of skeletal deformity or function, liver or lung problems, endocrine abnormalities, dental issues or neurological and neurocognitive dysfunction. Read more about Permanent Consequences and Late Effects of LCH.
The Histiocytosis Association works closely with the Histiocyte Society, which is dedicated to studying the histiocytic disorders. Through this unusual partnership, understanding of this disease has greatly increased, and survival rates and quality of life continue to improve.
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