Cholesteatoma is a cystic lesion in the middle ear that is not a true tumor. It is called cholesteatoma because the cyst contains cholesterol crystals in addition to exfoliated epithelium and keratinized tissue. Congenital cholesteatomas are divided into congenital cholesteatomas and acquired cholesteatomas. Congenital cholesteatomas develop when part of the embryonic tissue is left in the skull during the embryonic period; acquired cholesteatomas are usually caused by a history of secretory or purulent otitis media, which leads to obstruction of the drainage channels in the middle ear, negative pressure leading to an invaginated pouch, or epithelium growing from the perforated tympanic membrane into the tympanic cavity, and eventually the squamous epithelium is shed and accumulates, followed by infection and inflammation. The inflammation occurs as a result of infection. Cholesteatoma has an expansive growth characteristic and can therefore compress surrounding tissues to destroy resorption, leading to destruction of the auditory chain, facial nerve canal, and the cranial bone separating the middle ear from the skull. Patients with middle ear cholesteatoma without infection may be asymptomatic in the early stages, followed by varying degrees of hearing loss. Because the cholesteatoma itself serves as a bridge for sound transmission, the hearing loss is not very serious, but when it affects the cochlea, it can cause deafness in severe cases. Therefore, surgery is needed after the diagnosis is clear.