Histiocytosis X is seen in except -

Ans. is 'd' i.e., Torres syndrome Langerhans cell histiocytosis (Histiocvtosis X) C.) Histocytosis X is characterized by proliferation of Langerhans histiocytes (tissue macrophages). o It is subdivided into three categories : - i) Letterer - Siwe syndrome ii) Hand -Schuller-Christian disease iii)Eosinophilic granuloma. o Tumor cells in each are derived from dendritic cells and express S-100, CD1 a and HLA-DR. o The presence of Birbeck granules in the cytoplasm is characteristic. o Under the electron microscope, Birbeck granules have a pentalaminar, rodlike, tubular apperance and sometimes a dilated terminal end (tennis - racket appearance).