Anti-Yo positive paraneoplastic limbic encephalitis associated with nasopharyngeal carcinoma: A rare case.

Paraneoplastic neurological syndromes are rare immune-mediated disorders that may develop independently of tumor stage or metastatic spread. Limbic encephalitis is an uncommon manifestation, and its occurrence in association with head and neck cancers is exceptionally rare. We describe a 42-year-old man who presented with subacute ataxia, tremor, dysarthria, and altered consciousness. Brain magnetic resonance imaging revealed hyperintensities in the left hippocampus, parahippocampal gyrus, and amygdala, while cerebrospinal fluid analysis demonstrated lymphocytic pleocytosis, elevated protein levels, oligoclonal bands, and positivity for anti-Yo antibodies. Concomitant imaging identified a nasopharyngeal mass, which was subsequently confirmed as keratinizing nasopharyngeal carcinoma. The patient was treated with high-dose intravenous corticosteroids and immunoglobulin, resulting in complete neurological and radiological recovery. To our knowledge, this is the first reported case of anti-Yo positive paraneoplastic limbic encephalitis associated with nasopharyngeal carcinoma, underscoring the importance of considering paraneoplastic etiologies in atypical neurological presentations and demonstrating the potential for favorable outcomes with timely immunomodulatory therapy.