Metastatic Lung Adenocarcinoma in the Spinal Cord with a Negative Positron Emission Tomography and Computed Tomography (PET/CT) scan

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1 C a s e R e p o r t J. of Advanced Spine Surgery Volume 5, Number 1, pp 28~32 Journal of Advanced Spine Surgery JASS Metastatic Lung Adenocarcinoma in the Spinal Cord with a Negative Positron Emission Tomography and Computed Tomography (PET/CT) scan Jung-Ho Park, M.D., Ph.D. 1), Jae-Young Hong, M.D., Ph.D. 1), Si-Young Park, M.D., Ph.D. 2), Seung-Woo Suh, M.D., Ph.D. 3), Sung-Woo Hong, M.D. 1) Department of Orthopedics, Korea University Ansan Hospital, Seoul, South Korea 1) Department of Orthopedics, Korea University Anam Hospital, Seoul, South Korea 2) Department of Orthopedics, Korea University Guro Hospital, Seoul, South Korea 3) Although metastatic lung adenocarcinoma in the spinal cord is rare, it can be diagnosed by positron emission tomography and computed tomography (PET/CT) scan with high sensitivity during the early disease stage. A clinical and radiographic review was performed to present a rare case of an intradural intramedullary adenocarcinoma metastasis in the spinal cord with a negative PET/CT scan. A 75-year-old man with a diagnosis of lung cancer without metastasis confirmed by a negative PET/CT scan with no spinal symtoms (conducted 6 weeks previously) presented with progressive paralysis of both lower extremities and accompanying bowel and bladder symptoms. He underwent radical lobectomy of left lung under diagnosis of lung cancer without distant metastasis 6 weeks ago. Emergent MRI was performed, and MRI revealed a large intradural intramedullary mass compressing the spinal cord and extending from T12 to L1 with anterior compression of the spinal cord. Surgical decompression and tumor resection from T12 to L1 by lumbar laminectomy and durotomy were performed under a microscope. And, a diagnosis of adenocarcinoma to the spinal cord was made based on histopathologic findings. Postoperatively, the patient s neurologic status was not significantly improved. Despite a negative PET/CT scan finding with no neurologic symptoms or pain, surgeons should not exclude the possibility of a spinal metastatic lesion with lung cancer. Key Words: Intradural intramedullary metastasis, Adenocarcinoma, Lung cancer, PET/CT scan Introduction Although metastatic involvement of the extradural spine has been well described, spread of a primary cancer to the intradural spinal compartment is uncommon, and accounts for 6% of metastases to the spine. 1,2) However, intradural intramedullary spinal metastasis can have catastrophic neurologic symptoms, and thus, early diagnosis and treatment are required to improve curability and quality of life. Recently, positron emission tomography and computed tomography (PET/CT) scan commonly performed as a screening tool which shows the high sensitivity and specificity, and early detection of metastatic lesions by PET/CT is known to improve survival. 3-5) And, if there exist no spinal symptoms with negative PET/CT scan findings, surgeons would concentrate on the treatment of primary lesion, which can minimize the cost and time to rule out distant metastasis. Here, we report a rare case of metastasis to the spine from lung adenocarcinoma, which was not detected by PET/CT at initial diagnosis, and which rapidly progressed with neurologic deficits. Corresponding author: Si-Young Park, M.D., Ph.D. Department of Orthopaedic Surgery, Spine Surgery Division Korea University, College of Medicine, Anam Hospital, Seoul, South Korea TEL: , FAX: drspine90@kumc.or.kr 28 Copyright 2015 Korean Society for the Advancement of Spine Surgery

2 Fig. 1. Plain radiogram and axial CT scan of the chest which shows the huge adenocarcinoma located in right lower lung. A B C Fig. 2. Whole body PET/CT scan which shows the hot uptake in right lower lung (A, B), without any metastatic lesion in T12-L1 area (C). Description of patient A 75-year-old man presented at our ER with abrupt onset paralysis of both lower extremities. Initial neurologic examination revealed GIII weakness of lower extremities with bowel and bladder symptoms. The patient had been diagnosed to have primary lung cancer 6 weeks previously. At initial diagnosis, although there exist no neurologic deficit or spinal symptoms, a metastasis work up was performed including a whole body PET/CT scan, but failed to depict a metastatic lesion on the spinal column or other organs (Fig. 1, 2). And, radical lobectomy was performed under the diagnosis of solitary adenocarcinoma of the lung. However, at this presentation (6 weeks after index surgery), spinal MRI was performed in ER to determine the cause of the neurologic symptoms, which revealed a huge intradural intramedullary mass, isointense on T1 and hyperintense on T2 sequences with uniform contrast enhancement. The lesion extended from T12 to L1, with anterior compression of the backwardly displaced spinal cord (Fig. 3). Emergent surgical decompression was performed from T12 to L1 via lumbar laminectomy, and a poorly marginated, highly vascular, intradural intramedullary mass was found to displace the spinal cord with infiltration of the medulla. Radical removal was performed under an operating microscope. However, postoperatively, no significant change in neurologic con- 29

3 dition was evident, and a histopathologic examination revealed large, spherical, nucleated cells with prominent nucleoli and alveolar structures, indicating metastatic adenocarcinoma. In addition, immunohistochemistry showed that the nuclei of tumor cells were strong positive for thyroid transcription factor 1 (Fig. 4). All findings supported a diagnosis of metastatic adenocarcinoma originating from the lung. Discussion Intramedullary spinal cord metastasis, also termed parenchymal spinal cord metastasis, is a rare clinical entity, and an autopsy series reported its presence in % of cancer patients. 2,6,7) However, the majority of patients present with rapid onset symptoms referable to the spinal cord, such as, pain, weakness, sensory loss, and incontinence. As the Fig. 3. Lumbar spine MRI which shows the intramedullary mass extended from T12 to L1 with uniform contrast enhancement. A B Fig. 4. Histopathologic photo which shows (A) the large spherical, nucleated cells with prominent nucleoli and alveolar structures (H & E), and (B) nuclei of tumor cells with positive staining in thyroid transcription factor 1 (CK7). 30

4 disease progresses, patients often deteriorate and manifest the symptoms of complete spinal cord transection. Approximately 20% of patients can ambulate independently in at diagnosis, 40% are ambulatory but require an assistive device, and the other 40% are non-ambulatory. 8) Accordingly, the detection and early treatment of metastatic lesions in the spinal cord are as important as cure of the primary lung lesion. Therefore several diagnostic tools have been used to detect the metastatic lesions in early stage. And, whole body PET scan is often used to diagnose metastatic lesion, and can detect pre-radiologic lesions which can be screened at pre-clinical period. 9,10) After its discovery in the 1970s, PET scan became an important diagnostic modality. And, since the first proof of concept combined positron emission tomography and computed tomography (PET/CT) system started to operate in 1980s, PET/CT has developed into the fastest growing imaging modality worldwide. 3-5,11) PET/CT improves the anatomic localization of abnormalities identified by PET and reduces the number of false result. And, currently available data indicate that PET/CT is extremely sensitive and specific in diagnosis of carcinoma which cannot be detected by other diagnostic tools.11 Accordingly, surgeons depend on PET/CT scans as a screening tool, and treatment strategies are routinely based on the findings obtained. And, if there exist no spinal symptoms with negative scan findings, surgeons would concentrate on the treatment of primary lesion, which can minimize the cost and time to rule out distant metastasis. In the described case, the initial PET/CT scan and radiology findings failed to depict any significant finding in the spinal cord without any neurologic deficit or spinal symptoms. However, only 6 weeks later MRI visualized a huge mass in the T12-L1 area with aggressive infiltration, and neurologic compromise. Although intradural spinal metastasis from a primary adenocarcinoma of the lung have been reported on several occasions, no report has previously described a PET/CT negative case of metastasis from lung adenocarcinoma to the spine with abrupt neurologic deficit. We believe in the described case that either abnormally fast metastatic tumor growth had occurred over the 6-week period and that the mass was not detected by PET/CT at initial diagnosis, or that the specific characteristics of the cancer caused it to be undetectable by PET/CT which means the possibility of false negative PET/ CT scan result in detection of the lung cancer. However, we believe that had we detected the metastatic lesion before neurologic compromise had occurred, the post-surgical outcome would have been substantially better or that we would have been able to adopt a different treatment strategy (radiotherapy or chemotherapy). Accordingly, we caution surgeons not to rely too heavily on negative scan findings, despite the excellent reliability of PET/CT scan as a screening tool. Here we report the first case which shows the falsenegative PET/CT scan with evident metastatic lesion, and give a question to consider adding other diagnostic modality despite the cost implications. Conclusion We present this unusual thought-provoking case, which suggests that PET/CT findings be approached judiciously. And, surgeons should consider this aspect in treatment of spinal metastatic lesion. REFERENCES 1. Kim DY, Lee JK, Moon SJ, et al. Intradural spinal metastasis to the cauda equina in renal cell carcinoma: a case report and review of the literature. Spine (Phila Pa 1976) 2009;34:E Kotil K, Kilinc BM, Bilge T. Spinal metastasis of occult lung carcinoma causing cauda equina syndrome. J Clin Neurosci 2007;14: Czernin J, Allen-Auerbach M, Schelbert HR. Improvements in cancer staging with PET/CT: literature-based evidence as of September J Nucl Med 2007;48 Suppl 1:78S-88S. 4. von Schulthess GK, Steinert HC, Hany TF. Integrated PET/CT: current applications and future directions. Radiology 2006;238: Weber WA, Figlin R. Monitoring cancer treatment with PET/CT: does it make a difference? J Nucl Med 2007;48 Suppl 1:36S-44S. 6. Li D, Brennan JW, Buckland M, et al. Bronchogenic carcinoid metastasis to the intramedullary spinal cord. 31

5 J Clin Neurosci;17: Winkelman MD, Adelstein DJ, Karlins NL. Intramedullary spinal cord metastasis. Diagnostic and therapeutic considerations. Arch Neurol 1987;44: Chamberlain MC, Eaton KD, Fink JR, et al. Intradural intramedullary spinal cord metastasis due to mesothelioma. J Neurooncol;97: Potti A, Abdel-Raheem M, Levitt R, et al. Intramedullary spinal cord metastases (ISCM) and non-small cell lung carcinoma (NSCLC): clinical patterns, diagnosis and therapeutic considerations. Lung Cancer 2001;31: Tsimpas A, Post NH, Moshel Y, et al. Large cell neuroendocrine carcinoma of the lung metastatic to the cauda equina. Spine J;10:e Papathanassiou D, Bruna-Muraille C, Jouannaud C, et al. Single-photon emission computed tomography combined with computed tomography (SPECT/CT) in bone diseases. Joint Bone Spine 2009;76: 폐선암환자에있어 PET/CT 음성척수신경전이암에대한치료 박정호 1), 홍재영 1), 박시영 2), 서승우 3), 홍성우 1) 고려대학교안산병원정형외과학교실 1), 고려대학교안암병원정형외과학교실 2), 고려대학교구로병원정형외과학교실 3) 척수로의전이성폐암은매우드물게보고되어지고있으며, PET/CT 등으로진단되어지고있다. 75세남자환자가폐암으로진단받았으나, 증상이없었고, PET/CT등에서음성반응이나왔으나, 약 6주후양측하지마비로내원하였으며, 대소변장애또한동반하고있었다. 환자는폐전절제술및 MRI를시행받았으며, MRI 검사상 T12-L1 부분에전이성경막내전이성종양이발견되었으며, 이에대해외과적절제가시행되었다. PET/CT등의검사에서음성반응이나오더라도전이성척수종양을의심해볼필요가있다고사료된다. 색인단어 : 폐선암, PET/CT, 척추전이암 32