Histiocytosis X is seen in except :: (A) Hand schuller Christian disease, (B) Eosinophilic granuloma, (C) Letter-siwe syndrome, (D) Torres syndrome
Answer is D. 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).