Anti-Tr/DNER Antibody-Associated Paraneoplastic Neurological Syndrome Complicated with Warthin Tumor: a Case Report and Literature Review.

Generally, paraneoplastic neurological syndrome (PNS) associated with anti-delta/notch-like epidermal growth factor-related receptor (anti-Tr/DNER) antibodies primarily presents with cerebellar ataxia and is frequently complicated by Hodgkin's lymphoma (HL). Extracerebellar manifestations are relatively rare, and cases in the absence of an underlying malignancy are rare. Here, we report a 60-year-old patient presenting with scanning speech, proximal limb weakness, gait ataxia, and a palpable neck mass. The paraneoplastic syndrome antibody test showed that both serum and cerebrospinal fluid (CSF) anti- Tr/DNER antibodies were positive. A 5-day regimen of intravenous immunoglobulin and high-dose dexamethasone led to neurological improvement. The patient exhibited enhanced proximal muscle strength (from grade 4- to 4+) in the lower extremities and partial recovery in coordination. The pathology of the right upper cervical mass was consistent with Warthin tumor. Re-examination of serum and cerebrospinal fluid Tr/DNER antibodies remained positive. We describe a case of probable PNS characterized by anti-Tr/DNER antibody-associated cerebellar ataxia and a pathologically confirmed benign Warthin tumor. This case expands the known phenotype of anti-Tr/DNER disorders, underscoring the importance of antibody testing in rapidly progressive cerebellar ataxia even in the absence of a detectable malignancy.