Histiocytosis

Alternative names:

eosinophilic granuloma; Hand-Schuller-Christian disease; histiocytosis X; Langerhans cell histiocytoses; Letterer-Siwe disease; nonlipid reticuloendotheliosis; pulmonary histiocytosis X; pulmonary langerhans cell granulomatosis

Definition:

A generic name that includes any 1 of 3 possibly related syndromes characterized by a increase in the number of histiocyte cells in the blood; with an unknown cause.

Causes, incidence, and risk factors:

Pulmonary histiocytosis is characterized by inflammation of the small airways (bronchioles) and the small blood vessels in the lungs. This inflammation leads to stiffening (fibrosis) and destruction of the walls of the alveoli. The cause is unknown.

People 30 to 40 years old are affected most often. Cigarette smoking is a risk factor for pulmonary histiocytosis. Spontaneous pneumothorax occurs frequently in this condition. Histiocytosis occurs in about 1 out of 10,000 people.

Histiocytosis may also be manifest in childhood. In children histiocytosis is typified by bone involvement (80%) and may consist of single or multiple sites. The skull is a frequent site of involvement. The tumors produce a punched-out appearance in the bone X-ray. Tumors in the weight bearing bones such as the legs or spine may fracture spontaneously. Systemic involvement may cause rashes, pulmonary problems, enlargement of the spleen and liver, anemia, and death.

Children over 5 years old often have only bone involvement. However, those surviving for long periods often continue to have problems. Young children, especially infants, are more likely to have systemic involvement and a fatal outcome.