Bilateral inverted papilloma of the middle ear with intracranial involvement and malignant transformation: first reported case.

Inverted (Schneiderian) papilloma (IP) is a benign but locally aggressive tumor that is typically located in the sinonasal tract. Middle ear involvement and intracranial extension are rare. We present a patient with a history of a completely resected right nasal cavity IP that returned 7 months later with hearing loss, bilateral aural fullness, and right-sided facial weakness. Work-up revealed middle ear IP, and the patient underwent bilateral mastoidectomies. On both sides, the disease caused erosion of the tegmen and was adherent to the underlying dura. There was dehiscence of the carotid canal wall on the left. On the right, the tumor was discovered to have recurred 3 months after initial resection, resulting in complete facial nerve paralysis and trigeminal paresthesias. A right temporal bone resection was undertaken along with neurosurgery. The IP was discovered to have invaded through the dura of the temporal lobe, incase the internal carotid artery, and infiltrate the trigeminal nerve. The facial and vestibulocochlear nerves were sacrificed on the right. Pathology of the right temporal bone revealed malignant transformation to squamous carcinoma. The patient was referred to radiation oncology for postoperative therapy. To our knowledge, this is the first case of bilateral IP of the middle ear with intracranial involvement and malignant transformation. Discussion points include: 1) management of middle ear IP, 2) carotid canal wall dehiscence in erosive middle ear disease, 3) aggressive surgical excision in locally destructive middle ear tumors, and 4) the role of radiation therapy in malignant transformation of IP.