This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Ear, Subject name: ENT
[{'content': 'Cholesteatoma commonly associated with: \nSelect and explain. \nA. Atticoantral CSOM, B. Tubotympanic CSOM, C. Tympanosclerosis, D. Foreign body in ear', 'role': 'user'}, {'content': 'Answer: A \nExplanation: (a) Atticoantral CSOM(Ref. Scott Brown, 8th ed. Vol 2; 989)Tympanosclerosis is hyalinisation and calcification of the fibrous layer of tympanic membrane. It is not associated with cholesteatoma. Foreign body in ear does not lead to cholesteatoma formation.Keratosis obturans is the collection of desquamated keratin debris in the external auditory canal. This keratin debris comes from the external auditory canal stratified squamous epithelium.', 'role': 'assistant'}]