An 88-year-old male patient visited our hospital due to back pain with the symptom onset of three months ago. He had a history of left pneumonectomy due to pulmonary tuberculosis 30 years ago. He showed no neurologic deficit on physical examination and no abnormal laboratory findings.
The patient underwent contrast-enhanced chest CT. A left paravertebral lobulated mass measuring approximately 8 cm was noted at the T6 level with homogenous enhancement, compromising the left neural foramen and central spinal canal with spinal cord compression (Fig. 1A). Another smaller mass similar to the previous one was noted in the right paravertebral space at the same level, compromising the right neural foramen and central spinal canal. The continuity between the two paravertebral masses was unclear. Associated bony erosions were suspected at the T6 vertebra and left 6th costovertebral junction. A large amount of loculated fluid collection was noted in left hemithorax with partially calcified uneven pleural thickening, suggesting chronic empyema. Enlarged lymph nodes were seen in the both paratracheal and subcarinal areas, and the left para-aortic space of the upper abdomen.
On spinal MRI, bilateral paravertebral masses revealed diffuse T1 low and T2 heterogeneous high signal intensity (SI) with direct invasion of the epidural space at the T6 level (Fig. 1B). Continuity between the two paravertebral masses was not identified. There was bone marrow SI change in the vertebral body of T6 and the lower endplate of T5 with no evidence of bony cortical destruction or widening of the neural foramen. Bone marrow SI change was also noted in the posterior arc of the left 6th rib.
In consideration of unusual CT and MRI findings, advanced age of the patient, and history of chronic empyema, there was a high probability of malignancy, and our primary radiologic diagnosis was malignant lymphoma. Malignant mesothelioma and sarcoma, which are known to have association with chronic empyema, were included in the radiologic differential diagnosis. Multiple lymphadenopathies and suspected metastatic bone lesions supported the probability of malignancy. As the tumors extended through the neural foramen into the spinal canal, a possibility of malignant neurogenic tumors such as malignant schwannoma can be taken into account; however, there was no significant neural foraminal widening on imaging findings.
On subsequent fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT, the bilateral paravertebral masses revealed intense FDG uptake (maximum standardized uptake value = 14.3, Fig. 1C). There were hypermetabolic bone lesions in T5-7 vertebrae, bilateral 6th and left 7th ribs, and enlarged mediastinal and upper abdominal lymph nodes also revealed high FDG uptake, suggesting metastasis.
A CT-guided coaxial needle biopsy of the left paravertebral mass was successfully performed (Fig. 1D). On microscopic examination of the biopsy specimen, hypercellular spindle cell tumor was observed with moderate to marked nuclear pleomorphism and increased mitotic activity (> 5/10 on high power fields), arranged in a storiform pattern and intratumoral staghorn vascular structure. And those findings were suggestive of malignant SFT (Fig. 1E), Immunohistochemistry revealed positive staining for CD99, and negative staining for CD34 (Fig. 1F). An excisional biopsy with surgical management was planned for the next step but was not performed due to the deterioration of the patient's general condition. The patient received radiation therapy targeting the T6 vertebra for a month and was followed up at an outpatient clinic. Follow-up imaging studies after the radiation therapy revealed no significant interval change during the period of 4 months. However, unfortunately, the patient suddenly died due to acute duodenal perforation.
This study was approved by our Institutional Review Board, which waived the requirement for informed consent (IRB No. SCHUH 2022-04-004).