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Inflammatory process in external auditory canal (EAC) associated with ectopic proliferation of squamous tissue causing osteolysis.

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Very rare disease, representing 0.1–0.5% of otologic disease

Clinical features

The clinical presentation of EACC is that of an elderly male with otorrhea and chronic dull earache:

Otalgia and otorrhea (M/C features)
Other features: External ear canal occlusion, hearing loss, itching

More extensive disease may present with labyrinthine fistula and facial nerve dysfunction

Radiology

HRCT imaging:

Stage I	EACC limited to external auditory canal
Stage II	EACC invades TM and middle ear
Stage III	EACC creates defect of EAC and involves air cells in mastoid
Stage IV	EACC beyond temporal bone

4 stages of external auditory canal cholesteatoma (EACC) on temporal bone computed tomography. (A) Stage I. The lesion was within the external auditory canal. (B) Stage II. The lesion invaded the middle ear. (C) Stage III. The lesion invaded the mastoid cavity. (D) Stage IV. The lesion extended beyond the temporal bone. | Shin, S. H., Shim, J. H., & Lee, H. K. (2010). Classification of external auditory canal cholesteatoma by computed tomography. Clinical and experimental otorhinolaryngology, 3(1), 24–26. https://doi.org/10.3342/ceo.2010.3.1.24

MR imaging:

Application of DWI was a breakthrough with cholesteatomas depicting high signal intensity due to T2 shine through and partly because of diffusion restriction

The right external auditory canal lesion is iso to hypointense on T1 (arrow in A) and predominantly hyperintense on T2 (arrow in B) | Aswani, Y., Varma, R., & Achuthan, G. (2016). Spontaneous external auditory canal cholesteatoma in a young male: Imaging findings and differential diagnoses. The Indian journal of radiology & imaging, 26(2), 237–240. https://doi.org/10.4103/0971-3026.184419

Diffusion weighted imaging (A) and apparent diffusion coefficient map (B) reveal restricted diffusion by a lesion situated in the right external auditory canal (arrow) | Aswani, Y., Varma, R., & Achuthan, G. (2016). Spontaneous external auditory canal cholesteatoma in a young male: Imaging findings and differential diagnoses. The Indian journal of radiology & imaging, 26(2), 237–240. https://doi.org/10.4103/0971-3026.184419