Intradural-Extramedullary Metastatic Tumor from Lung Cancer-A Case Report and Review

Abstract

A 62-year-old male presented with a thoracic intradural-extramedullary metastasis from lung cancer. He complained of walking difficulty and bilateral lower leg numbness. He had a past history of lung adenocarcinoma three years prior. Thoracic spine magnetic resonance imaging showed that the tumor occupied the right subarachnoid space and spinal nerve roots had shifted to the left side at Th12. He was diagnosed with cauda equina syndrome by an intradural-extramedullary tumor. Surgery was performed (Th12 laminectomy) and we opened the dura mater and arachnoid membrane. The tumor was in the right side and was removed. After the operation, his neurological condition soon improved and he could walk with a cane. By four moths postoperatively, a metastatic brain tumor occurred and he had to use a wheel chair. He died one year after surgery. Immunohistochemical staining was positive for thyroid transcription factor-1 in both the lung adenocarcinoma and intraduralextramedullary tumor. We diagnosed a metastatic tumor. Including the present case, 102 cases of a metastatic intradural-extramedullary tumor have been reported and, thus, the condition may not be rare. In more than twenty years there have only been two case studies, which recommended both operative and non-operative methods. We reviewed the validity of an operation base on the prognosis and surgical results of previous reports. The average life expectancy was 8.6 months. The functional improvement rate was 78%. We recommend an operation for an intradural-extramedullary metastatic tumor because it improves the quality of a patients' short life. Keywords: IntroductionMetastases are by far the most common skeletal tumors seen by orthopedists, and the spine is the most common site of skeletal involvement [1]. A spinal epidural metastasis is the most common neoplastic myelopathy [2]. In a total of 1215 cases of primary lung cancer in an autopsy study, 20 (1.65%) revealed intradural parenchymal involvement [3]. Among 200 patients treated for symptomatic spinal metastases, a localized intradural extramedullary tumor was discovered in 10 cases [4]. Among 136 patients who underwent surgery for spinal metastases, an intradural extramedullary tumor was observed in two cases (1.5%) [5]. To our knowledge, Rogers et al. [6] were the first to report on an intradural-extramedurally metastatic tumor in 1958 since then, 101 cases have been reported in 66 articles . Including our case, the total number of reported cases is now 102. Many authors have described an intradural-extramedullary metastasis as a rare metastatic condition, however, we do not consider it to be rare given the number of reported cases.Two types of treatment have been reported for an intraduralextramedullary tumor, the recommended operative and nonoperative methods [4,18,31,38,45,63]. In two case studies, Perrin et al.[4] recommended a non-operative method and Chow et al.[30] recommended an operation. Both reports had a small number of cases (n=10). There have been no reviews of many cases that were n...