Fahim et al. Journal of Medical Case Reports 2010, 4:408 http://www.jmedicalcasereports.com/content/4/1/408 The most frequent neoplasms associated with PLE are small cell lung cancer, testicular tumors, thymoma, Hodgkin’s lymphoma and breast cancer. In an analysis of 50 patients with PLE, Gultekin and colleagues [4] found that lung cancer was the most common neoplasm identified in 50% of cases, followed by testicular and breast carcinoma in 20% and 8%, respectively. The neu- rological symptoms preceded the diagnosis of cancer in approximately two-thirds of patients with a median duration of three and a half months. Paraneoplastic limbic encephalitis can pose a diagnos- tic challenge in patients with cognitive impairment, especially when there is no evidence of malignant dis- ease, and can be easily mistaken for viral encephalomye- litis or rapidly progressive neurodegenerative disease. Even in the presence of malignancy, the neurological symptoms can be easily attributed to cranial metastases. An MRI scan of the brain is the most sensitive radi- ological investigation to diagnose limbic encephalitis. Typically, it shows hyperintense lesions in the medial temporal lobes and these are best visualized in T2 and axial FLAIR sequences without significant contrast enhancement. A CSF examination is seldom diagnostic of this condition, and the most common findings are consistent with inflammatory changes (pleocytosis, increased protein, oligoclonal bands and increased immunoglobulin content). Anti-neuronal antibodies are frequently found in the serum or CSF of patients with PLE, but the absence of these antibodies does not exclude the diagnosis. The most common is the anti-Hu antibody, which is present in about 50% of patients with small cell lung cancer presenting with limbic encephali- tis and the anti-Ta antibody associated with testicular cancer [4]. Moreover, the presence of antibodies can be predictive for a good response to immunosuppressive therapy [5]. Electroencephalography can be a useful tool in order to support the diagnosis of limbic encephalitis, as it can demonstrate focal or generalized slowing and/or sharp wave epileptiform activity predominantly in the tem- poral regions [6]. The treatment should be directed at the associated malignancy, which frequently improves the neurological symptoms and is superior to immuno- modulatory therapy. Conclusion Our patient’s case highlights the importance of consid- ering PLE in the differential diagnosis of altered mental status in patients with lung malignancy, if there is no readily identifiable cause of cognitive impairment on initial investigations. Prompt diagnosis and early treat- ment of malignancy provides the best chance of clinical improvement in patients with this rare disorder. Page 4 of 4 Consent Written informed consent was obtained from the patient for publication of this case report and any accompanying images. A copy of the written consent is available for review by the Editor-in-Chief of this journal. Acknowledgements We thank Dr A Campbell for providing Figures 4 and 5 and Dr R Hill, Dr G Avery and Dr R Bartlett for their advice on the radiological images presented in this case report. Author details 1Department of Cardiovascular and Respiratory Studies, Castle Hill Hospital, Cottingham, UK. 2Department of Oncology, Castle Hill Hospital, Cottingham, UK. 3Respiratory Medicine, Castle Hill Hospital, Cottingham, UK. Authors’ contributions AF, DVM and MB contributed to the writing of the manuscript. All authors read and approved the manuscript. Competing interests The authors declare that they have no competing interests. Received: 18 January 2010 Accepted: 17 December 2010 Published: 17 December 2010 References 1. Corsellis JA, Goldberg GJ, Norton AR: ’Limbic encephalitis’ and its association with carcinoma. Brain 1968, 91:481-496. 2. Rosenfield MR, Dalmau J: Paraneoplastic limbic encephalitis associated with small cell lung cancer. Comm Oncol 2007, 4:491-494. 3. Bakheit AM, Kennedy PG, Behan PO: Paraneoplastic limbic encephalitis: clinico-pathological correlations. J Neurol Neurosurg Psychiatry 1990, 53:1084-1088. 4. Gultekin SH, Rosenfield MR, Voltz R, Eichen J, Posner JB, Dalmau J: Paraneoplastic limbic encephalitis: neurological symptoms, immunological findings and tumour association in 50 patients. Brain 2000, 7:1481-1494. 5. Storstein A, Bru A, Vedeler CA: Limbic encephalitis-a diagnostic challenge. Tidsskr Nor Laegeforen 2007, 127:3077-3080. 6. Lawn ND, Westmoreland BF, Kiely MJ, Lennon VA, Vernino S: Clinical, magnetic resonance imaging, and electroencephalographic findings in paraneoplastic limbic encephalitis. Mayo Clin Proc 2003, 78:1363-1368. doi:10.1186/1752-1947-4-408 Cite this article as: Fahim et al.: A case of limbic encephalitis presenting as a paraneoplastic manifestation of limited stage small cell lung cancer: a case report. Journal of Medical Case Reports 2010 4:408. Submit your next manuscript to BioMed Central and take full advantage of: • Convenient online submission • Thorough peer review • No space constraints or color ﬁgure charges • Immediate publication on acceptance • Inclusion in PubMed, CAS, Scopus and Google Scholar • Research which is freely available for redistribution Submit your manuscript at www.biomedcentral.com/submit