Teaching NeuroImages: Prosopagnosia heralding anti-NMDA receptor encephalitis

A 23-year-old right-hand-dominant woman presented with 3 weeks of progressive difficulty recognizing faces, including her own, subsequently developing psychosis. Noncontrast CT head and MRI brain with contrast revealed a nonenhancing lesion of the right posterior temporal lobe and fusiform gyrus, with corresponding hypermetabolism on FDG-PET/CT brain (figure). EEG demonstrated right posterior temporal slowing. CSF and serum anti–NMDA receptor (NMDAR) antibodies were positive, with CT abdomen/pelvis revealing ovarian teratoma. Teratoma removal, plasmapheresis, and 1 cycle of rituximab yielded symptom resolution over 1 month. Anti-NMDAR encephalitis rarely presents with prosopagnosia,1 and in this case, is likely secondary to right fusiform gyrus dysfunction.2