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
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: 
Select and explain. 
A. Histiocytosis X, B. Wegener's granulomatosis, C. Retinoblastoma, D. Chediak-Higashi syndrome
A: Histiocytosis X
Answer: A: Histiocytosis X 
Explanation: 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.