CT and MRI findings of intracranial extraskeletal mesenchymal chondrosarcoma-a case report and literature review

Background: Intracranial extraskeletal mesenchymal chondrosarcoma (EMCS) is a rare neoplasm and often misdiagnosed before histopathological examination due to its rarity. There were few reports previously on the radiological features of intracranial EMCS. We described a 20-year-old male patient with intracranial EMCS focusing on the imaging characteristics. Case Description: The patient was admitted to our hospital due to headache and dizziness for two months, without nausea, vomiting, limb convulsions and loss of consciousness during the illness. Pre-contrast computed tomography (CT) revealed a large slightly hyperdense mass with irregularly lobulated margins in the right parietal and occipital region and multiple patchy calcifications in peripheral of the lesion. The inner table of right parietal bone adjacent to the mass was compressed, thickened, and eroded. Magnetic resonance imaging (MRI) exhibited intermediate and hypo-intensity on T1-weighted images (T1WI) and slight hyperintensity on T2-weighted images (T2WI) with extremely high intensity rim of cerebral spinal fluid (CSF) and low intensity flow-void vessel. The mass demonstrated heterogeneous remarkable enhancement and "dural tail" sign also was noted. The important imaging signs of this case are irregular calcifications of soft tissue on CT and "dural tail" sign on MRI. The patient underwent tumor resection and was followed up postoperatively with serial MRI every three months. He was alive without obvious clinical symptoms and evidence of recurrence for 9 months. EMCS is a highly invasive tumor and it is difficult to differentiate EMCS from the other intracranial malignant tumors only by clinical characteristics or findings of CT and conventional MR imaging. Radiotherapy and chemotherapy after radical resection are the best treatment choice. Therefore, postoperative patients should be reviewed routinely. Conclusions: A knowledge of the imaging features could facilitate differentiation of intracranial EMCS, but the final diagnosis depends on pathological examinations. This paper focuses on the imaging characteristics of EMCS and fully describes the details of lesions in order to provide clinicians with effective differential diagnosis information and improve clinical decision-making.