Fahim et al. Journal of Medical Case Reports 2010, 4:408 http://www.jmedicalcasereports.com/content/4/1/408 C A S E R E P O R T JOURNAL OF MEDICAL CASE REPORTS Open Access A case of limbic encephalitis presenting as a paraneoplastic manifestation of limited stage small cell lung cancer: a case report Ahmed Fahim1*, Mohammad Butt2, Damian V McGivern3 Abstract Introduction: The differential diagnosis of altered mental status and behavioral change is very extensive. Paraneoplastic limbic encephalitis is a rare cause of cognitive impairment, which should be considered in the differential diagnosis. Case presentation: A 64-year-old British Caucasian woman presented to our hospital with a 12-week history of confusion and short-term memory loss. She was hyponatremic with a serum sodium level of 128mmol/L. Moreover, there was evidence of left hilar prominence on the chest radiograph. A thoracic computed tomography scan showed left hilar opacity with confluent lymphadenopathy. A percutaneous biopsy confirmed a diagnosis of small cell lung cancer. There was no radiological evidence of brain metastasis on the computed tomography scan. In view of continued cognitive impairment, which was felt to be disproportionate to hyponatremia, a magnetic resonance imaging scan of the brain was undertaken. It showed hyperintense signals from both hippocampi, highly suggestive of limbic encephalitis presenting as a paraneoplastic manifestation of small cell lung cancer. She had a significant radiological and clinical response following chemotherapy and radiotherapy. Conclusion: This case highlights the importance of considering paraneoplastic syndromes in patients with neurological symptoms in the context of lung malignancy. If initial investigations fail to reveal the cause of cognitive impairment in a patient with malignancy, magnetic resonance imaging may be invaluable in the diagnosis of limbic encephalitis. The clinical presentation, diagnostic techniques and management of paraneoplastic limbic encephalitis are discussed in this case report. Introduction The differential diagnosis of cognitive impairment in a patient with lung malignancy is extensive. Paraneoplastic neurological syndromes, including limbic encephalitis, should be suspected as a cause of altered behavior and short-term memory loss, if the more common causes (brain metastasis, biochemical derangement, infection or drug related delirium) have been excluded. We report a case of paraneoplastic limbic encephalitis (PLE) asso- ciated with limited stage small cell lung cancer, which highlights the importance of considering this entity as a cause of cognitive dysfunction in a patient with lung carcinoma. * Correspondence: ahmedfahim@doctors.org.uk 1Department of Cardiovascular and Respiratory Studies, Castle Hill Hospital, Cottingham, UK Full list of author information is available at the end of the article Case presentation A 64-year-old British Caucasian woman with a medical history of fibromyalgia, hypertension and asthma pre- sented to our hospital with collapse and brief loss of consciousness. Our patient had no recollection of the event, and she did not have a history of witnessed seizures. According to her family, she had experienced progressively worsening short-term memory for the pre- vious three months. She was a lifelong smoker with a 50-pack-year history. Her medications included citalo- pram, co-amilozide, salbutamol and beclomethasone inhalers. On examination, she was hemodynamically stable with pulse rate of 60 beats/minute and blood pressure of 107/75. Oxygen saturations were 95% on air. Her abbre- viated mental test score was 7/10. On neurological examination there was no evidence of nystagmus, © 2010 Fahim et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.