Benign glandular peripheral nerve sheath tumor of the seventh and eighth cranial nerve complex.

A unique, deep-seated, benign, glandular peripheral nerve sheath tumor (PNST) of the cerebellopontine angle is described. The tumor arose from the seventh and eighth cranial nerve complex in a 15-year-old boy without neurofibromatosis. Histologically, benign glands were embedded in a bland spindle cell stroma. The epithelial cells were immunoreactive for CAM 5.2, and focally for chromogranin. The spindle cells were positive for S100P. The benign glandular PNST unassociated with neurofibromatosis is a controversial entity. The superficial location of most reported cases has made it difficult to exclude entrapped adnexae as a source for the glands. This tumor was separate from the internal auditory meatus on MRI scan, the most likely source of entrapped glands at this site. This case is the first report of a deep-seated, benign, glandular peripheral nerve sheath tumor. It suggests that glandular differentiation in PNSTs, while unusual, is not synonymous with neurofibromatosis or malignancy.