histiocytosis, Langerhans cell

histiocytosis, Langerhans cell (histiocytosis X, Langerhans cell disease),

n a group of diseases characterized by a proliferation of ab-normal histiocytoid cells. Includes: 1. Chronic disseminated histiocytosis (Hand-Schūller-Christian disease);
2. Acute disseminated histiocytosis (Letterer-Siwe disease); and
3. eosinophilic granulomas.