Rare malignant primary spinal intradural extramedullary mesenchymal chondrosarcoma: a case report and literature review

Background: Mesenchymal chondrosarcoma (MCS) is a rare malignant chondrosarcoma with a high propensity for recurrence and distant metastasis. MCS usually arises from bone tissue, and rarely occurs outside the bone. MCS in the subdural and extramedullary regions of the spinal cord is especially rare. In this article, we report a case of spinal intradural extramedullary MCS with herpes virus infection, which is the first such case reported in East China. Case Description: A 13-year-old male complained of intermittent low-grade fever, sweating, progressive constipation with weakness of both lower extremities and bilateral hypoesthesia after a 5-month history of herpes virus infection. Spinal magnetic resonance imaging (MRI) revealed a subdural-extramedullary solid nodular mass with isointensity on T1-weighted imaging and hyperintensity on T2-weighted imaging that was located behind the superior margin of the T5 vertebral body. The patient was initially diagnosed with thoracic meningioma and underwent spinal cord tumour resection followed by adjuvant chemotherapy. Histopathological examination revealed that the tumour was mainly composed of round or oval cells and mesenchymal chondroid matrix, and gene analysis showed the fusion of HEY1 exon 4 to NCOA2 exon 13. Both test results were consistent with the diagnosis of primary intraspinal MCS. At the 1-year follow-up, the patient received adjuvant chemotherapy, and the reexamination images revealed no evidence of tumour in situ tumour recurrence or distant metastasis. Conclusions: As more research has been done on MCS, it has been found that the disease is more likely to occur in adolescents, but is often overlooked due to its lack of imaging characterization. Therefore, the misdiagnosis rate can be reduced only by closely considering clinical manifestations with pathology and imaging findings. Although MCS is a highly malignant tumour, early primary spinal intradural extramedullary MCS can cause neurological symptoms, early detection and treatment can achieve basic total surgical resection. Postoperative adjuvant chemoradiotherapy can further reduce recurrence.