Paraneoplastic Limbic Encephalitis Associated with Adenocarcinoma of Lung

Paraneoplastic limbic encephalitis (PLE) is a rare, immune-mediated entity. We present an unusual case of a patient who has double cancers and two different paraneoplastic neurological syndromes.

A 58-year-old gentleman has histories of adenocarcinoma of lung and malignant thymoma associated with myasthenia gravis, which underwent surgery and chemotherapy 3 years ago. This time, he presented to our ward with rapidly progressive memory decline and myoclonic jerks in his limbs for two weeks. Magnetic resonance imaging (MRI) of brain showed increased signal intensity over bilateral mesial temporal regions on T2 Fluid Attenuated Inversion Recover (FLAIR) series. Chest computed tomography showed cancer recurrence. He received steroid pulse therapy firstly and right lung lower lobe lobectomy later. Pathology report of the tumor was recurrent adenocarcinoma. After the immunotherapy and tumor resection, his mentality improved gradually. Six months later, brain MRI showed resolution of bilateral temporal hyperintensity with residual mesial temporal atrophy.

From our case, we would like to emphasize that paraneoplastic limbic encephalitis should be considered among the differential diagnosis of rapidly progressive dementia associated with myoclonus, along with other neurodegenerative diseases. Depending on its underlying malignancy, the cognitive impairment may be substantially reversible, despite atrophy of mesial temporal lobes.