SECTION EDITOR: C. DOUGLAS PHILLIPS, MD
Diagnosis: Suspected arachnoid cyst of the right cerebellopontine angle
The patient's MRI images revealed a 21 × 16-mm lesion isointense to cerebrospinal fluid (CSF) in the right cerebellopontine angle without evidence of contrast enhancement, which was causing minimal mass effect on the anterior cerebellum with anterior displacement and compression of several lower cranial nerves, including the origin of the vestibulocochlear nerve. This lesion has imaging characteristics that are consistent with a diagnosis of an arachnoid cyst, although this is impossible to confirm absent a formal histologic examination. There was no evidence of endolymphatic sac or duct enlargement. It was concluded that the patient had a Meniere's disease–like clinical syndrome caused by compression of the vestibulocochlear nerve by the suspected arachnoid cyst.
Radiology Quiz Case 1: Diagnosis. JAMA Otolaryngol Head Neck Surg. 2013;139(5):520-521. doi:10.1001/jamaoto.2013.2653b