HISTIOCYTOSIS

Histiocytic disorders are a group of heterogeneous diseases. A logical classification can be based on the type of proliferating cell, either monocyte-macrophage or Langerhans/dendritic cell, and depends whether the proliferating cells are ''reactive'' or malignant. The classifica tion now mainly depends on the histological examination. Regarding Lan gerhans cell histiocytosis (Hand-Schiller-Christian disease, Letterer- Siwe disease and eosinophilic granuloma), the diagnosis, suspected on various clinical signs, is confirmed with histological examination sho wing infiltration with CD1 positive histiocytes disclosing intracytopl asmic Birbeck granules at electron, microscopic examination. The progn osis depends on the patient's age at onset and the extension of the di sease. Treatment is based on chemotherapy and corticotherapy.