ANTI-MA2 encephalitis mimicking diencephalic demyelinating syndrome

•Lesions in diencephalon can be present in several types of neurological conditions.•Symptoms of paraneoplastic encephalitis may develop days or months before primary tumor be found.•Diencephalic involvement in patients with anti-Ma2 may cause cataplexy, as well as endocrinological conditions. Anti Ma 2 encephalitis is an autoimmune encephalitis, usually paraneoplastic, characterized by isolated or combined limbic, diencephalic, or brainstem dysfunction. Limbic encephalitis (LE) is the most common manifestation. Anti-Ma2 LE can also be manifested as a pure psychiatric disturbance associated or not with hypokinesia. Other patients exhibit excessive daytime sleepiness, vertical ophthalmoparesis, or both associated with LE, due to diencephalic and/or upper brainstem involvement. These cases are challenging and demand extensive work-up for differential diagnosis.