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What is Birbeck's granule is seen? and explain in detail?
Ans. is 'c' i.e., Langerhan's cells histocytosis Langerhans cell histiocytosis (Histiocytosis-X)* Histocytosis X is characterized by proliferation of Langerhans histiocytes (tissue macrophages). It is subdivided into three categoriesi) Letterer - Siwe syndromeii) Hand -Schuller-Christian diseaseiii) Eosinophilic granuloma* Tumor cells in each are derived from dendritic cells and express S-100, CD la and HLA-DR. The presence of Birbeck granules in the cytoplasm is characteristic. Under the electron microscope, Birbeck granules have a pentalaminar, rodlike, tubular apperance and sometimes a dilated terminal end (tennis - racket appearance).