Acoustic cellular schwannoma invading the petrous bone: case report.

Cellular schwannoma, a variant of benign schwannomas characterized by a high pseudosarcomatous cellularity, rarely involves the cranial nerves. In this report, we present the case of a 74-year-old woman with a cellular schwannoma of the VIIIth cranial nerve, which recurred from an ordinary schwannoma resected 9 years before. The tumor has been controlled for 35 months by a simple re-excision, indicating the benign nature of this tumor, although the tumor showed bone destruction and a high MiB-1 labeling ratio.