This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pathology
Langerhan’s histiocytosis was previously known as 
Select and explain. 
A. Eosinophilic granuloma, B. Pyogenic granuloma, C. Letterer siwe disease, D. Histiocytosis x
D: Histiocytosis x
Answer: D: Histiocytosis x 
Explanation: Langerhan’s histiocytosis was previously known as Histiocytosis X , it includes
Eosinophilic granuloma
Letterer siwe disease
Hand Schuller Christian disease