Introduction:
A cholesteatoma is a locally destructive mass of the petrous bone that rarely grows
extratemporally. An extratemporal extension is found mainly in medial cholesteatomas.
Methods:
Case report of a patient with an extensive cholesteatoma of the temporal bone with
compression of the posterior fossa and midline displacement.
Case study:
A 59-year-old male presents with tinnitus on the left side and vertigo. An MRI showed
a 6 cm expansive tumor of the left temporal bone, which displaced the parenchyma of
the cerebellum. A CT of the petrous bone presented an erosion of the posterior semicircular
canal as well as an enlargement of the aqueduct vestibuli.
Intraoperatively it showed a temporal bone cholesteatoma, which could be removed by
opening the posterior fossa and performing a radical mastoidectomy. It also showed
a vertical mucosal fold appeared along the long process of the incus, separating the
anterior epitympanon and mesotympanon from the antrum and allowing to develope a congenital
cholesteatoma behind. The cholesteatoma invaded the aqueduct vestibuli, which explains
the aqueduct vestibuli shown enlarged on the preoperative CT. The canal of the facial
nerve was destroyed over a distance of 2 mm in the mastoid, and the posterior semicircular
canal was destroyed over a distance of 3 mm and was exposed. Immediate coverage of
semicircular dehiscence revealed an unchanged postoperative bone conduction hearing
threshold.
Conclusion:
As differential diagnosis, this case is valuable because the dilatation of the aqueduct
vestibuli was the result of the cholesteatoma and not the cause – as in an idiopathic
"enlarged vestibular aquaeduct syndrome".
