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Histiocytosis    See images

Overview | Symptoms | Treatment | Prevention

Alternative names:

Histiocytosis X; Eosinophilic granuloma; Pulmonary histiocytosis X; Nonlipid reticuloendotheliosis; Pulmonary langerhans cell granulomatosis; Hand-Schuller-Christian disease; Letterer-Siwe disease; Langerhans cell histiocytoses

Definition:

"Histiocytosis" is a generic name for syndromes characterized by an abnormal increase in the number of histiocyte cells (also called monocytes, macrophages, or dendritic cells) in the body. It is separated broadly into 3 classes of histiocytoces:  (1) Langerhans cell histiocytosis (histiocytosis X); (2) Non-Langerhans cell histioscytosis (hemophagocytic syndromes); (3) malignant histiocytosis syndrome (not discussed here).

Causes and Risks

One class of histiocytosis, which tends to occur more in adults, Pulmonary histiocytosis X, 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 (90% of patients). Spontaneous pneumothorax occurs frequently in this condition.

Most cases of histiocytosis, however, occur between the ages of 1 and 15 years old, the incidence peaking between 5 to 10 years of age. The total incidence of histiocytosis is thought to be roughly one in two hundred thousand people each year.

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. However, there is often systemic involvement (whole body) causing rashes, pulmonary problems, gum infiltration, lymph gland involvement, endocrine problems, enlargement of the spleen and liver, anemia, and in some circumstances, 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.

The non-malignant disease has been thought of a cancer like disease, but more recently researches feel it behaves similar to an autoimmune-like phenomenon. Some forms are genetic.

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