eosinophilic granuloma, Hand-Schuller-Christian disease and Letterer-Siwe disease.

Histiocytosis X is a generic term that refers to an increase in the number of histiocytes, a type of white blood cell, that act as scavengers to remove foreign material from the blood and tissues.

Xanthogranuloma is a form of histiocytosis, an excess of histiocytes, with yellow lesions.

a biopsy, that is, taking a tissue sample under anesthesia from a site in the patient thought to be involved. Blood and urine tests, chest and other x rays, magnetic resonance imaging (MRI)

Epidermal (skin) Langerhans cells (a form of dendritic cell) accumulate with other immune cells in various parts of the body and cause damage by the release of chemicals.