A woman in her 40s with history of a vestibular schwannoma presented for routine follow-up. Four years prior, she developed sudden unilateral low-frequency sensorineural hearing loss (SNHL) and imbalance. A left-sided vestibular schwannoma measuring 32 × 35 mm was documented on magnetic resonance imaging (MRI). She underwent a retrosigmoid approach for gross resection. Postoperative examination showed a left facial nerve paralysis. Two years later, follow-up imaging demonstrated residual tumor growth and a region of enhancing tissue involving the left mastoid and jugular foramen with a craniocaudal dimension of 1.3 cm. She underwent Cyber Knife radiotherapy (1800 cGy) and was followed with serial imaging. Her physical examination revealed stable facial nerve paralysis and unilateral SNHL. Two months later, MRI demonstrated increased intensity of the heterogeneous mastoid tissue on T1-weighted imaging (Figure, A), whereas T2-weighted images demonstrated a hypointense lesion (Figure, B). Computed tomography revealed an infiltrating process with bony erosion of the posterior fossa and labyrinth, involving the jugular foramen and carotid canal. No hypervascularity of the mass was noted on diagnostic cerebral angiography. The patient underwent temporal bone biopsy via a left-sided mastoidectomy (Figure, C and D). The mass was found to occupy the inferior portion of the mastoid cavity, adjacent to the mastoid tip, and infiltrating the external auditory canal.
Feng AL, Weinreich HM, McCarthy EF. Persistent Temporal Bone Lesion After Vestibular Schwannoma Resection. JAMA Otolaryngol Head Neck Surg. 2016;142(3):289-290. doi:10.1001/jamaoto.2015.3204