Paraneoplastic Neurological Syndromes Associated With Parotid Cancer Expressing the Zic4 Antibody: A Case Report

Paraneoplastic neurological syndromes (PNS) are rare, immune-mediated disorders associated with cancer, often presenting with various neurological symptoms, such as encephalomyelitis, limbic encephalitis, and rapidly progressive cerebellar syndrome. A 66-year-old woman presented to our department with rapidly increasing swelling in her right parotid gland. Fine needle aspiration cytology confirmed parotid cancer, and a right parotidectomy and dermectomy were planned. Preoperatively, she experienced symptoms of nausea and vertigo and was later diagnosed with PNS based on the presence of Zic4 antibodies in the cerebrospinal fluid. Following methylprednisolone pulse therapy and tumor resection, the patient's symptoms resolved completely. Histopathological examination of the surgically excised tissues confirmed a diagnosis of salivary duct carcinoma. Immunohistochemistry revealed that the Zic4 antibody stained the nucleoli of tumor cells. This report presents the first documented case of PNS linked to parotid cancer expressing the Zic4 antibody, along with a review of 21 previous cases of PNS associated with head and neck cancers.