CNSC-09. OTOSYPHILIS MIMICKING A VESTIBULAR SCHWANNOMA

Abstract Vestibular schwannomas are common nonmalignant primary brain tumors representing up to 80% of the cerebellopontine angle (CPA) tumors. Their diagnosis is made radiographically in most cases with the presence of an enhancing mass along the 8th nerve complex. The United States is experiencing a surge in the number of recorded syphilis cases with an approximate 80% increase since 2018 according to the CDC, after reaching an all-time low in the year 2000. Syphilis can involve the Central Nervous System (CNS) in its early, late, and latent forms, and in its early stages it typically presents in the form of meningitis which can be accompanied by cranial neuropathies especially of the nerves II, VII, and VIII. We present a case of a 35-year-old man who presented with subacute onset unilateral left-sided hearing loss and dizziness that did not respond to prescribed steroids. Magnetic resonance imaging (MRI) revealed an enhancing mass in the left cerebellopontine angle presumed to be a vestibular schwannoma. The patient was subsequently planned for radiosurgery, however, MRI done during the procedure revealed that the mass was of a smaller size. The patient was referred to neuro-oncology and work up included cerebrospinal fluid (CSF) analysis that showed 3 white blood cells, normal protein and glucose, and negative VDRL. Cytology, flow cytometry, and inflammatory markers were negative. However, the Treponema pallidum antibodies were positive confirming otoshyphilis. The patient was treated accordingly with a course of Penicillin G with near resolution of the enhancement of the 8th nerve complex. His hearing remained impaired on his initial follow up, however, his facial weakness near resolved. This case brings up an important diagnostic question in cases of presumed schwannomas where patients would be otherwise treated solely based on the MRI appearance, especially given the re-emergence of syphilis.