



Histiocytosis is a general name for a group of syndromes that involve an abnormal increase in the number of immune cells called histiocytes.
There are three major classes of histiocytoses:
This article focuses only on Langerhans cell histiocytosis (histiocytosis X).
Histiocytosis X; Langerhans cell histiocytosis; Eosinophilic granuloma; Pulmonary histiocytosis X; Nonlipid reticuloendotheliosis; Pulmonary Langerhans cell granulomatosis; Hand-Schuller-Christian disease; Letterer-Siwe disease