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
[{'content': 'All are histiocytosis except - \nSelect and explain. \nA. Letterer siwe syndrome, B. Chloroma, C. Hand schuller christian triad, D. Eosinophilic granuloma', 'role': 'user'}, {'content': 'Answer: B \nExplanation: None', 'role': 'assistant'}]