Discussion

LE is one of the paraneoplastic syndromes in patients with malignant tumors. LE is common in patients with small-cell lung cancer, breast cancer, testicular tumors, teratomas, Hodgkin lymphoma, and thymomas. 1 Approximately 60% of patients with malignancies and LE have been reported to have specific autoantibodies for PNS, including anti-Hu, anti-Ma/Ta, and NMDA antibodies. 1, 2, 3 We suggest that the LE in our case was induced by nivolumab treatment based on the following findings. First, the onset of symptoms occurred after initiating nivolumab treatment, and the tumor regressed after nivolumab treatment. In general, the neurologic symptoms of PNS are known to precede the appearance of a tumor. Second, we ruled out plausible alternatives for LE, such as herpes encephalitis. In addition, this is the first reported case with anti-Hu antibody in which there was a pathologic examination of LE at the time of postmortem autopsy.