[A case of paraneoplastic limbic encephalitis associated with malignant lymphoma presenting with a late-onset bilateral thalamic lesion].

A 63-year-old man presented with cognitive impairment including disturbance of memory functions and character change. Fluid-attenuated inversion recovery (FLAIR) magnetic resonance (MR) imaging revealed signal hyperintensities in the bilateral medial temporal lobes. Cerebrospinal fluid analysis revealed high protein concentrations, positive results for the oligoclonal band, and a slightly positive result for glutamate receptor ε2 (GluRε2) antibody. Voltage-gated potassium channel (VGKC) antibody was slightly positive in serum. Computed tomography showed enlargement of the left supraclavicular, left axillary, and renal hilar lymph nodes, and 18 F-fluoro-2-deoxy-D-glucose positron emission tomography revealed increased uptake at the same sites. Lymph node biopsy findings were consistent with diffuse large B-cell lymphoma. Based on these findings, the patient was diagnosed with paraneoplastic limbic encephalitis (PLE) associated with malignant lymphoma. The patient received intravenous injection of immunoglobulin and R-CHOP chemotherapy, but his neurological condition deteriorated. MR imaging showed atrophic changes in the medial temporal lobes during immunotherapy and chemotherapy. FLAIR/T2-weighted imaging revealed signal hyperintensities in the bilateral thalami after the first course of R-CHOP chemotherapy. This is the first report of PLE associated with diffuse large B-cell lymphoma presenting with late-onset bilateral thalamic lesions.