Histiocytosis X is seen in except :

Langerhans cell histiocytosis (Histiocytosis X) : Histocytosis X is characterized by proliferation of Langerhans histiocytes (tissue macrophages). It is subdivided into three categories : - Letterer - Siwe syndrome. Hand -Schuller-Christian disease. Eosinophilic granuloma.. Tumor cells in each are derived from dendritic cells and express S - 100, CD1a and HLA - DR. The presence of Birbeck granules in the cytoplasm is characteristic. Under the electron microscope, Birbeck granules have a pentalaminar, rodlike, tubular appearance and sometimes a dilated terminal end (tennis - racket appearance).