This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Childhood Tumors, Subject name: Pediatrics
[{'content': "A child presents with seborrheic dermatitis, sinusitis and chronically draining ears. On examination child has failure to thrive, with hepatosplenomegaly and exophthalmos, probable diagnosis is: \nSelect and explain. \nA. Histiocytosis X, B. Wegener's granulomatosis, C. Retinoblastoma, D. Chediak-Higashi syndrome", 'role': 'user'}, {'content': "Answer: A \nExplanation: a. Histiocytosis X(Ref: Nelson's 20/e p 2484-2489, Ghai 8/e 620-621)The given clinical picture prints to a diagnosis Langerhans cell; Histiocytosis of previously called Histiocytosis X.", 'role': 'assistant'}]