Case of the Month
Section Editor: Nicholas Stence, MD
Children's Hospital Colorado, Aurora, CO
December 2019
Next Case of the Month Coming January 7...
Auto-Evacuated Secondary Acquired Cholesteatoma
- Background:
- Cholesteatoma (of the middle ear/mastoid): squamous epithelium in the middle ear or mastoid; desquamation results in continued accumulation of keratin debris, associated bone and soft tissue erosion, and recurrent infection.
- Cholesteatoma (of the middle ear/mastoid) types include primary acquired from invagination of a retraction pocket, secondary acquired from ingrowth of keratinizing epithelium into the middle ear through an existing TM perforation, and congenital from embryonic epithelial tissue within the temporal bone.
- A cholesteatoma has 3 components: cystic contents comprising desquamated keratin, matrix, and perimatrix (with the last 2 also being known as the “shell”).
- Sometimes an acquired cholesteatoma spontaneously evacuates into the external auditory canal, leaving a cavity (shell) within the granulation tissue in the shape of the original cholesteatoma, but now filled partially or totally with air instead of exfoliated keratin, which appears opacified. This is called an auto-evacuated (spontaneously drained) secondary acquired cholesteatoma (SAC).
- Clinical Presentation:
- Nonresolving chronic suppurative otitis media
- Progressive conductive hearing loss
- Key Diagnostic Features:
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CT: Typical findings of cholesteatoma include a sharply marginated expansile soft-tissue lesion, retraction of the TM, scutum blunting, and erosion of the tympanic tegmen and ossicles. The most frequent CT finding in partially or completely auto-evacuated SAC cases is a partially or completely empty circular or elliptical aerated cavity surrounded by granulation tissue.
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MR imaging with conventional techniques: not specific; usually hypointense/isointense on T1WI and hyperintense on T2WI compared with brain; indistinguishable from granulation tissue
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MR imaging with novel techniques: Irrespective of their type (congenital or acquired), cholesteatomas appear to have high signal intensity on DWI, attributed partly to restricted water diffusion and predominantly to the T2 shine-through effect of the lesion as revealed by calculated apparent diffusion coefficient values.
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MR imaging coregistration: T2 and DWI coregistration combines the advantages of detecting cholesteatoma in DWI and locating cholesteatoma in high-resolution T2 imaging.
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- Differential Diagnoses:
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Inflammatory granulation
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Cholesterol granuloma
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Paraganglioma
- Schwannomas of the facial nerve and geniculate ganglion
- Facial nerve hemangioma
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- Treatment:
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Surgical removal or exteriorization via tympanoplasty or tympanomastoidectomy with primary or secondary ossicular chain reconstruction addresses chronic otitis media.
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