Paraneoplastic limbic encephalitis with late-onset magnetic resonance imaging findings: A case report.

Paraneoplastic limbic encephalitis (PLE), a paraneoplastic neurological syndrome (PNS), is a rare nervous system disorder that results from the indirect effects of tumors and is commonly associated with small-cell lung cancer (SCLC). Previous studies have reported that magnetic resonance imaging (MRI) may be useful for diagnosing LE. Temporal lobe abnormalities are observed using T2-weighted and fluid-attenuated inversion recovery sequences; however, such abnormalities are detected in only 60% of patients with PLE. The present study describes a case of PLE associated with SCLC, in which LE was observed using MRI 26 days after the first convulsive seizure. Although the serum and cerebrospinal fluid analyses for onconeural antibodies were negative, the findings of this case indicate that PLE should be considered in the differential diagnosis, and that repeated brain MRI may be more helpful for diagnosis, as the brain MRI findings may be normal during the early stages of PLE.