Congenital cholesteatoma localized to the tip of the mastoid bone: a case report and possible etiology.

Congenital cholesteatomas of mastoid origin are extremely rare. We reported one in 2007 and experienced an additional case. A male presented with a 5-month history of right-sided ear discharge. Computed tomography of the temporal bone showed a soft tissue density occupying the mastoid tip. At surgery, the cholesteatoma sac was completely isolated from the mastoid antrum and lateral air cell in the mastoid tip area. We now doubt the rarity of this entity. With a brief literature review, we consider how the cholesteatoma localizes to the tip of the mastoid bone.