Ophelia Syndrome: Rare Paraneoplastic Encephalitis Following Complete Metabolic Remission in Hodgkin Lymphoma.

Paraneoplastic neurological syndromes (PNS), including limbic encephalitis, are rare associations with Hodgkin's lymphoma (HL), typically occurring before diagnosis. The term "Ophelia syndrome" describes this specific association. We report a rare case of paraneoplastic encephalitis developing after complete metabolic remission in a 16-year-old girl with HL, as assessed on 18 F-FDG PET/CT. Despite seronegative findings for autoimmune encephalitis panels, 18 F-FDG PET/CT demonstrated hypometabolic areas corresponding to magnetic resonance imaging Fluid-Attenuated Inversion Recovery (FLAIR) sequence hyperintensities, consistent with autoimmune encephalitis. This case highlights the importance of 18 F-FDG PET/CT in evaluating atypical neurological symptoms and suggests that PNS may arise even after apparent oncologic remission.