Computed tomography in malignant external otitis.

Malignant external otitis is a severe infection of the external auditory meatus occurring predominantly in diabetics and usually caused by Pseudomonas aeruginosa. The infection may spread along several routes: directly by bony erosion into the adjacent mastoid bone, anteriorly into the parotid gland and temporomandibular joint and inferiorly into the soft tissues of the infratemporal fossa. We present four cases of malignant external otitis that illustrate the typical patterns of spread of this disease and the role that radiology, and in particular computed tomography, plays in its diagnosis and management.