Metastatic Spinal Tumor from Benign Pleomorphic Adenoma: Case Report and Literature Review

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Purpose: Pleomorphic adenomas tend to arise in the salivary glands. They are rare and histologically benign but can result in distant metastasis, and their characteristics need further investigation. We report a case of locally recurring benign primary palatal pleomorphic adenoma that resulted in spinal metastases and review the relevant literature. Case Report: A 58-year-old woman had undergone surgery for a palatal pleomorphic adenoma 22 years earlier and 6 subsequent operations for local recurrences. During follow-up, metastases to multiple organs, including the spine, were diagnosed and 4 CyberKnife treatments were performed. She suffered right flank pain and slight paralysis of the right leg; radiological findings showed a growing metastatic spinal tumor. She underwent removal of a thoracic vertebral tumor and posterolateral fusion. Postoperatively, her symptoms improved. Histopathological analysis indicated a pleomorphic adenoma and no evidence of malignancy. Although there was no local recurrence, 23 months after surgery, a fifth CyberKnife procedure was performed for a growing salivary gland tumor and she is currently being followed up. Conclusion: We described a rare case of benign pleomorphic adenoma that metastasized to the spine. Long-term follow-up for recurrence and metastasis is required for patients with benign pleomorphic adenoma.