Fahim et al. Journal of Medical Case Reports 2010, 4:408 http://www.jmedicalcasereports.com/content/4/1/408 Page 3 of 4 Figure 4 Histology from a computed tomography (CT)-guided lung biopsy showing infiltration of the left lower lobe with neoplastic cells, consistent with small cell lung cancer. cognitive function improved considerably over the course of next few months and her condition remained stable 18 months after presentation. Discussion Paraneoplastic limbic encephalitis, first described as a clinical entity in 1968 [1] is characterized by short-term memory deficits, mood and behavioral changes and rela- tive preservation of other cognitive functions. There may be seizures, which are most often partial complex in nature. Moreover, hypothalamic involvement can manifest with hyperthermia, hyperphagia or pituitary hormonal deficits [2]. Patients with PLE often present with symptoms of neurological involvement distant from the limbic system (commonly brainstem and Figure 6 Axial fluid attenuation inversion recovery (FLAIR) MRI of the brain showing a bright signal from the medial temporal lobe on the left side (arrow) consistent with limbic encephalitis. cerebellum). Bakheit and colleagues [3] found that only 32% of patients had isolated limbic encephalitis. The neurological symptoms often precede identification of the tumor by weeks or months and the non-specific nat- ure and diversity of symptoms add to the difficulty in diagnosing this rare clinical entity. Figure 5 Immunohistochemistry of a lung biopsy specimen showing positive staining with CD56, suggestive of small cell carcinoma of lung. Figure 7 Hyperintense signal from the hippocampus/medial temporal lobe on the right (arrow).