Limbic encephalitis secondary to malignant thymoma.

A 56-year-old woman presented with memory loss and an enlarging mediastinal mass on chest roentgenogram. Physical findings were normal except for an altered mental status examination consistent with dementia. Further radiologic assessment was nondiagnostic. Surgical resection of a malignant thymoma resulted in clinical improvement. Treatment for limbic encephalitis should be directed at the underlying disease, and symptoms may improve if the tumor is eradicated.