Not So Benign: A Rare Atypical Ectopic Choroid Plexus Papilloma

Choroid Plexus Papillomas (CPPs) are rare neoplasms (0.4-0.6 % of all brain tumors) arising from cuboidal epithelial cells of the choroid plexus. Atypical choroid plexus papillomas are even more rare and characterized by aggressive features of increased mitotic activity and frequent metastases even at diagnosis. Atypical choroid plexus papillomas accounted for 9% of choroid plexus tumors in the Surveillance Epidemiology and End Results (SEER) Database from 1978 to 2009. We describe a 56 year-old woman with a rare atypical choroid plexus papilloma ectopically located in the cerebellopontine angle and mistaken for a vestibular schwannoma or glossopharyngeal schwannoma. She demonstrated leptomeningeal seeding involving multiple cranial nerves and spinal cord. Besides papilledema she developed several neuro-ophthalmic features slowly over time from involvement of cranial nerves and subsequent intraparenchymal spread and radiation necrosis in the brainstem. Besides being rare, the cerebellopontine angle location of this tumor is also extremely uncommon making this a very unique case.