Paraneoplastic neurological syndrome as initial presentation of pulmonary adenocarcinoma.

Paraneoplastic neurological syndromes are defined as remote effects of cancer that are not caused by the tumour and its metastasis, or by infection, ischaemia or metabolic disruptions. The author reports a 63-year-old Caucasian woman presenting with slowly progressing cognitive deficits. Initial workup failed to reveal any obvious cause of her cognitive deficits. Retrospective medical data review revealed a pulmonary nodule, which on further evaluation revealed pulmonary adenocarcinoma with metastatic spread to liver and spine. MRI of the brain did not reveal any metastatic lesion. Cerebrospinal fluid analysis revealed the presence of anti-Hu antibody and a diagnosis of limbic encephalitis was made. Limbic encephalitis is an inflammatory process localised to structures of the limbic system that produces cognitive impairment along with other neuropsychiatric symptoms. This case highlights the importance of considering paraneoplastic syndromes in patients presenting with cognitive deficits.