Negligence actions are unlikely to arise from the treatment of genuine cases of otitis externa, but there is some possibility of actions arising where an alternative diagnosis has been overlooked. Failure to diagnose malignant otitis externa may have fatal consequences, while failure to diagnose complicated suppurative otitis media may also have serious adverse consequences. Malignant otitis externa must be suspected in any case of outer ear inflammation attended by severe pain which occurs in an elderly patient who is or may be immunologically compromised (eg a diabetic). In acute suppurative otitis media, the history differs from that of otitis externa because the first symptom is pain, rising to a crescendo and usually relieved by the appearance of discharge, because the pain in this instance is due to pus under tension in the middle ear; the rupturing of the tympanic membrane, which releases discharge into the ear canal, relieves this pain. There may then be further pain due to mastoiditis or secondary otitis externa.