An Axial CT image of an 82-year-old diabetic man shows marked thickening of the right pinna (arrowhead) and external auditory canal (arrows) without extension to the skull base or evidence of mastoiditis.
Facts: Malignant Otitis Externa
- Severe infection of the external auditory canal (EAC) and skull base
- Elderly diabetics and immunocompromised patients
- Most common organism = P. aeruginosa
- Extension into deep structures or chronic osteomyelitis may occur without signs on local examination
- Potential complications: osteomyelitis of the temporomandibular joint, sigmoid sinus thrombosis, meningitis, optic neuritis
- Biopsy usually required to exclude carcinoma
Staging
- Stage 1 = confined to EAC and/or facial nerve paralysis
- Stage 2 = osteitis of the skull base and/or multiple cranial nerve involvement
- Stage 3 = meninges or brain involvement
Imaging
- CT commonly used to define location, extent of disease.
- MRI may complement CT in cases with cranial nerve, brain involvement
- Imaging monitoring of diseases may be done with bone scan and/or gallium scan
Reference:
Okpala NCE, Siraj QH, Nilssen E, Pringle M. Radiological and radionuclide investigation of malignant otitis externa. J Laryngol Otol 2005;119:71-75.
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