Encephalitis mediated by antibodies against the metabotropic glutamate receptor subtype 5 (mGluR5) is always paraneoplastic and associated with Hodgkin's lymphoma.79 The signs of this extremely rare condition (only seven cases reported) include marked and subacute memory loss, depression, delusions, hallucinations, and psychosis together with tumor symptoms of cachexia, fever, and night sweats. Here, GRM5 is linked to viral encephalitis.