Cholesterol granuloma of the petrous apex is a newly recognized clinical entity distinct from cholesteatoma. Cholesterol granuloma usually produces symptoms of trigeminal, facial, and abducens nerve palsy and may not affect the auditory nerve. The characteristic computerized cranial tomographic (CCT) finding is a nonenhancing, smooth-walled, expansile lesion that is isodense with brain tissue in a patient with bilaterally well pneumatized mastoids and petrous apices. Treatment is limited to drainage of the cyst and insertion of a stent for permanent aeration of the petrous apex. Of ten cases of cholesterol granuloma of the petrous apex recently diagnosed at the Otologic Medical Group, the correct preoperative diagnosis was made in nine patients on the basis of CCT findings. Six of the nine patients had serviceable hearing preoperatively; serviceable hearing was maintained postoperatively in five patients.

These radiologic changes may help distinguish ELSTs from other tumors of the temporal bone and posterior fossa.

Cholesterol granuloma of the petrous apex is a readily recognizable and treatable entity that is more common than previously realized. Cholesterol granuloma grows slowly in the petrous apex as a mass lesion until it produces hearing loss, tinnitus, vertigo, and facial twitching. Twelve cases of cholesterol granuloma of the petrous apex are illustrated; ten of these are analyzed in detail, especially with respect to CT findings. A sharply and smoothly marginated expansile lesion in the petrous apex, isodense with brain and nonenhancing on CT, is in all probability a cholesterol granuloma. Cholesterol granuloma and cholesteatoma of the petrous apex are different lesions and treated differently. Cholesterol granuloma can be treated simply and effectively by drainage and permanent fistulization. Preoperative recognition by CT is important for planning proper treatment.

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The diagnostic contributions of computed tomography (CT) and magnetic resonance (MR) imaging were compared in 12 patients with benign intratemporal vascular tumors (hemangioma or vascular malformation). The tumors included six in the internal acoustic canal and six in the geniculate ganglion region. Clinical and histologic correlations were made. Two of the six patients with tumors in the internal acoustic canal underwent CT, and both required gas cisternography to show the tumor. Five patients in that group underwent MR imaging, and all five studies showed the tumor. All six patients with geniculate ganglion tumors underwent CT. Results in one study were questionable, and five showed the tumor. Five patients in this group underwent MR imaging, but the MR findings were positive in only two cases. MR imaging should therefore be performed before CT in the evaluation of facial nerve dysfunction, as it demonstrated all tumors in the internal acoustic canal and some in the geniculate ganglion region. If MR findings are negative, CT should then be performed to rule out a possible geniculate ganglion lesion.