Concurrent Complete Spinal Cord Syndrome and Sixth Cranial Nerve Palsy in Advanced Adenoid Cystic Carcinoma: A Case Report and Literature Review

Adenoid cystic carcinoma (ACC) with intracranial metastasis and sixth cranial nerve (CN VI) palsy, spinal metastases, and malignant spinal cord compression is an uncommon clinical entity. We present a case of a patient exhibiting this constellation of findings secondary to the parotid ACC. A 55-year-old man with no identifiable risk factors for ACC presented with a 10-year history of a left parotid tumor. He underwent two surgical resections and received one cycle of chemotherapy. Subsequently, his disease progressed locoregionally and systemically. He developed diplopia due to left sixth cranial nerve palsy caused by an intracranial metastatic lesion, together with complete spinal cord syndrome secondary to thoracic spinal metastases with malignant spinal cord compression. The patient was treated with whole-brain radiotherapy for intracranial metastasis and palliative spinal radiotherapy for spinal cord compression, achieving neurological stabilization without further deterioration. Systemic therapy with a tyrosine kinase inhibitor was subsequently initiated (lenvatinib 24 mg QD). The lungs are the most common site of distant metastasis in ACC, followed by bone and liver involvement. However, intracranial dissemination may occur rarely and should be considered in the clinical evaluation of these patients.