A female patient with breast cancer presenting with altered sensorium. The following MRI suggests:

The epidemiology of limbic encephalitis mimics that of the underlying malignancy. Tumours which can result in limbic encephalitis include: small cell carcinoma of the lung (classic cause); testicular germ cell tumors; thymic tumours; breast cancer; ovarian carcinoma; haematologic malignancies; gastrointestinal malignancie Clinical presentation: Clinical presentation typically causes sho-term memory loss and mental status changes. Seizures and psychosis have also been repoed . Radiographic features: MRI: High T2 signal without enhancement. Appearance is similar to herpes simplex encephalitis, and changes are most evident in the mesial temporal lobes. Bilateral involvement is most common (60%). PET scan: Can show increased FDG uptake . Differential diagnosis: Herpes simplex encephalitis - acute time course, presence of fever.