-Case Reports-

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

Hiroyuki Dan¹, Kyongsong Kim¹, Rinko Kokubo¹, Ryutaro Nomura², Daijiro Morimoto³ and Akio Morita³

¹Department of Neurological Surgery, Nippon Medical School Chiba Hokusoh Hospital, Chiba, Japan
²Department of Cyberknife Center, Chigasaki Central Hospital, Kanagawa, Japan
³Department of Neurological Surgery, Nippon Medical School, Tokyo, Japan

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.

J Nippon Med Sch 2023; 90: 121-125

Keywords
metastatic spinal tumor, pleomorphic adenoma

Correspondence to
Hiroyuki Dan, Department of Neurological Surgery, Nippon Medical School Chiba Hokusoh Hospital, 1715 Kamagari, Inzai, Chiba 270-1694, Japan
h-dan@nms.ac.jp

Received, September 12, 2021
Accepted, October 27, 2021