Trigeminal nerve schwannoma with ancient change. Case report and review of the literature.

Ancient change in a schwannoma is a histological variant typically found in longstanding tumors. Histologically, the tumor has biphasic features typical of a schwannoma with evidence of degenerative changes that may complicate diagnosis. The authors report on a 23-year-old man with no features of neurofibromatosis who presented with headaches, blurred vision, and ataxic gait. Magnetic resonance imaging demonstrated a rim-enhancing lesion in the cerebellopontine angle with displacement of brainstem structures and no supratentorial hydrocephalus. Using a lateral suboccipital approach together with image guidance and intraoperative neurophysiological monitoring, a gross-total macroscopic excision was performed. At surgery, the tumor was found to arise from the inferior division of the trigeminal nerve. The final histological diagnosis was schwannoma with ancient change. Note that ancient change in schwannomas is a histological variant thought to result from degenerative changes in longstanding tumors. To the authors' knowledge, this is the first independent report of this histological variant in an intracranial schwannoma.