![]() History and etymologyĮxternal auditory canal cholesteatomas were first reported by Toynbee in 1850. Prognosis depends on the extent at the time of diagnosis. Small lesions can be treated endoscopically under local anesthesia, whereas larger lesions need surgery to remove the cholesteatoma and affected bone areas. MRI cannot show the early involvement of compact bone. They appear as soft tissue attenuating lesions. High-resolution bone window temporal bone CT is the method of choice to localize the cholesteatoma and to demonstrate bony erosions. The Schüller, Stenvers, and Mayer views of the petrous bone have been largely replaced by CT. postoperative, postinflammatory, posttraumatic, radiation-inducedĪ special type of secondary cholesteatoma of the external auditory canal are those associated with congenital atresia of the external auditory canal.16) Yanaka K, Hyodo A, Fujimori H, Yoshii Y. B, The red arrow shows an arachnoid cyst (red circled) that is located laterally in the fundus of the IAC. puted tomography of the internal auditory canal and cerebellopontine angle. ClassificationĮxternal auditory canal cholesteatoma can be divided into: Nerves with normal course in the internal auditory canal (IAC). ![]() The distinction between keratosis obturans and cholesteatomas is not merely one of pedantry, but impacts on treatment strategy 3. The most useful findings confirming an external auditory canal cholesteatoma are focal osteonecrosis with or without sequestration and lack of epithelial covering of the bony surface 2. ![]() Both mainly consist of epithelial debris in the external acoustic canal. 1 VSs may remain within the internal auditory canal (IAC) or extend into the CPA. PathologyĪ distinction from keratosis obturans has been introduced only in the last few decades. Vestibular schwannomas (VSs) are benign neoplasms of the nerve sheath and account for 68 of all intracranial tumors and 80 of cerebellopontine angle (CPA) tumors. A less common presentation is conductive hearing loss due to canal occlusion 2. Patients often present with chronic dull otalgia and otorrhea. For comparison, the annual incidence of middle ear cholesteatoma is around 9.2 per 100,000. The overall incidence rate in one large study was 0.30 per year per 100,000 inhabitants 1. Many other masses can present at or around the cerebellopontine angle.The external acoustic canal is a rare location for a cholesteatoma with an estimated incidence of around 1.2 per 1,000 new otological patients. As the tumor becomes larger, degenerative changes may occur in its center with formation of cysts.
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