Geniculate ganglion meningiomas: CT and MR appearances.

A 19-year-old woman had three episodes of left facial paralysis, each with complete resolution. The initial computed tomographic (CT) scan was interpreted as normal (Fig 1A). The patient returned 1 year later with recurrent facial paralysis. Magnetic resonance (MR) imaging showed a mass at the geniculate turn (Fig 1B). Retrospective review of the initial CT findings revealed expansion of the distal labyrinthine segment of the facial nerve and geniculate turn. The bony margins were indistinct with suggestion of faint intratumoral bone. The presumptive diagnosis was an “ossifying” hemangioma. At surgery, a fibrotic tumor was present at the geniculate turn, which was excised along with the tumor. A greater auricular nerve graft was placed. At pathology, the mass was noted to compress the facial nerve. Microscopically, it demonstrated psammoma bodies with plump elongate spindle cells with a syncytial growth pattern. Immunohistochemical features were also consistent with the diagnosis of meningioma. Strong positive results were obtained with epithelial membrane antigen and vimentin. Stains for low-molecular-weight cytokeratin and factor VIII revealed normal levels. The patient had not regained any appreciable facial nerve function by 2 years after surgery.