Ancient Schwannoma Mimicking Glomus Jugulare
30 September 2019 (online)
Introduction Schwannomas are benign tumors arising from the nerve sheath. Schwannoma of the jugular foramen (JF) is rare. We report a case of ancient schwannoma arising from the JF, the first of its kind to be reported in the literature.
Case Report A 37-year-old male presented with ear pain, pulsatile tinnitus, reduced hearing in the left side since 6 months and ear discharge since 3 months. Past history of ear surgery was done for ear discharge 15 years back. No history of difficulty in speech and swallowing, nasal regurgitation, facial deviation, hemifacial spasms, or dizziness was reported.
On examination: left EAC–reddish polyp was present, did not bleed or pain on touch. Post aural scar was present. Right ear: normal. Audiological testing was suggestive of moderate conductive hearing loss on left and minimal hearing loss on right. There were no obvious neurological deficits on examination.
Investigations: HRCT showed skull base isodense lesion with extension into jugulare foramen—glomus jugulare (GJ). Contrast MRI well defined extra-axial, soft tissue enhancing mass in relation to the left CP angle involving petrous part of temporal bone with extension into the middle ear and external ear with salt and pepper appearance—GJ/Nerve sheath tumor. MRA showed encasement of the ICA by the lesion with no obvious feeders.
Treatment: patient underwent left side transmastoid transtemporal excision of the tumor. Intraoperatively ECV and IJV were ligated. Facial nerve was identified and transposed. Tumor mass completely removed in peacemeal, reconfirmed with endoscopic evaluation. Defect was sealed using abdominal fat graft. Postoperative grade-4 facial palsy noted. HPE: spindle cells arranged in sheets having elongated nuclei with hypocellular areas and nuclear atypia—s/o ancient schwannoma.
Discussion JF mass can be classified according to the structure of origin; it was to be extrinsic or intrinsic. Based on history and imaging characteristics, the diagnosis was thought to be GJ. But histopathological diagnosis was AS. There are four variants of schwannoma. AS is characterized by degenerative changes, such as hemorrhage, cystic degeneration, hyalinization and calcification. These characteristics mimic GJ on imaging giving salt and pepper appearance. Treatment is surgical excision since it is a benign tumor and radioresistant with good prognosis.
Conclusion Schwannomas of JF though rare has to be considered as a differential diagnosis for JF mass; however, the treatment remains the same with good prognosis.