Exostoses are usually asymptomatic unless they become large enough to cause a hearing loss by blocking the external canal or entrapping wax.
Exostoses may be circumscribed, or diffuse. They appear as small, hard, shiny, discrete round or oval excrescences, which are sometimes pedunculated and may be single or multiple.
The skin overlying the exostosis is usually thinner and paler than normal.
A single exostosis can be differentiated from a foreign body or cyst by gentle palpation with a blunt, ring ended probe.
In advanced cases three large exostoses arising from opposing sides of the canal can reduce the lumen to a tri-radiate star the "Mercedes Benz" sign.
Multiple coalescent exostoses are blocking the lumen of this patient's bony external auditory canal.
A small narrowed lumen can be seen in the anteroinferior quadrant.