Novel CT-guided biopsy of isolated perineural spread of adenoid cystic carcinoma along the trigeminal nerve masquerading as chronic trigeminal neuropathy.

The differential diagnoses for chronic peripheral neuropathy are broad and diagnosing a cause can be challenging. We present a case of isolated perineural spread of adenoid cystic carcinoma to the trigeminal nerve involving skull base foramina and Meckel's cave in the setting of chronic trigeminal neuropathy and no known prior malignancy. Computed tomography-guided core (CT) needle biopsy was needed to arrive at a diagnosis and a novel approach was required to obtain tissue from the trigeminal nerve lesion at foramen ovale.