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Alternate Names

  • pulmonary histiocytosis X
  • histiocytosis X
  • eosinophilic granuloma
  • nonlipid reticuloendotheliosis
  • Langerhans histiocytoses
  • Letterer-Siwe Disease
  • Hand-Schuller-Christian Disease
  • pulmonary Langerhans' granulomatosis


Histiocytosis refers to a group of disorders in which there is an abnormally high number of scavenger cells, called histiocytes, in the blood.

What is going on in the body?

Some histiocytosis diseases affect adults and others affect children. In adults, inflammation occurs in the small airways and small blood vessels in the lungs. The condition is often linked with cigarette smoking.
In children the bones, especially those of the skull, are involved. However, any other single site or multiple sites can be affected.


What are the causes and risks of the condition?

Although the cause of histiocytosis is unknown, it is much more likely to occur in a person who smokes cigarettes.


What can be done to prevent the condition?

There is no known prevention for histiocytosis. A person who stops smoking can reduce his or her risk of lung involvement.


How is the condition diagnosed?

In adults, the diagnosis of histiocytosis is made by:
  • chest x-ray
  • bronchoscopy, in which a small sample of the airways are removed and the airways are examined through a small scope
  • pulmonary function tests, a group of tests that measure the lungs' capacity to hold air, move air in and out, and exchange oxygen and carbon dioxide
In children the diagnosis is made by:
  • bone x-rays that show the "punched-out" appearance of bone lesions
  • x-rays of the entire body, to determine how much bone is involved
  • biopsies, or small samples, taken from the bone, bone marrow, and skin
  • blood tests

Long Term Effects

What are the long-term effects of the condition?

Histiocytosis can cause serious illness and even death in some children, while leaving others with minimal effects. The disease stabilizes in about half of affected adults. The others end up with permanent loss of lung function.

Other Risks

What are the risks to others?

There are no risks to others, as histiocytosis is not contagious.


What are the treatments for the condition?

Histiocytosis is treated with corticosteroids, such as prednisone, and methotrexate (i.e., Rheumatrex, Trexall). These help reduce inflammation in the lungs. Other medications, such as cyclophosphamide (i.e., Cytoxan), may also be tried.
However, no therapy is completely reliable in this disease. Sometimes radiation therapy is used to treat bone lesions. A person who smokes should stop smoking.

Side Effects

What are the side effects of the treatments?

Side effects vary depending on the medication, but may include allergic reactions.

After Treatment

What happens after treatment for the condition?

Complications can occur with histiocytosis. A sudden collapse of the lung, known as atelectasis, is common. This disorder can lead to death due to lung or heart failure.


How is the condition monitored?

A series of x-rays and pulmonary function tests may be needed to see how the histiocytosis changes over time. Any new or worsening symptoms should be reported to the healthcare professional.


The Merck Manual of Medical Information, 1997

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