Bilateral cavernous sinus involvement by perineural spread of inverted papilloma

BACKGROUND: Inverted papillomas (IPs) are benign sinonasal tumors of ectodermal origin that are slow growing but locally invasive, have a high rate of recurrence, and have significant malignant potential. They often invade surrounding bone and soft tissue but have never been described to spread perineurally. CASE: We report a case of a 53 year old female who initially presented with epistaxis 15 years ago and was found to have an inverted papilloma. After surgical resection, the patient developed multiple recurrences, all surgically resected, and most recently developed parasthesia in the left V2 distribution and diplopia in the left eye with imaging showing a soft tissue mass in the left posterior maxillary sinus and fullness in V2. The patient returned to the operating room where the maxillary sinus was positive for recurrent IP and perineural invasion was found of the infraorbital nerve. A follow-up MRI several months later showed fullness in both cavernous sinuses extending down to the second and third divisions of the trigeminal nerve. CONCLUSION: We propose that in aggressive forms, perineural spread can occur in IP. We also believe that additional investigations are required to characterize the pathophysiology involved in IP perineural spread.