Microcystic meningiomas (MCMs) and meningeal Ewing sarcoma/peripheral primitive neuroectodermal tumours (pPNETs) are difficult to differentiate because of the similarity in their image manifestation on magnetic resonance imaging (MRI). Differential diagnosis of these two tumours before surgery could contribute to ameliorating clinical decision-making, and predicting prognosis. Here, we aimed to comparatively analyse the difference between MRI and pathological findings of these two tumours. Thirteen cases of MCM and eleven cases of meningeal Ewing sarcoma/pPNET confirmed through pathology were analysed retrospectively. The imaging features of the two tumours were statistically analysed using the Chi square test. The average age of patients with MCM and meningeal Ewing sarcoma/pPNET was 47 ± 18.4 years and 20 ± 13.2 years, respectively. Features of MRI, including tumour morphology, dural tail sign, bony destruction, and distant metastasis, were significantly different between the two tumours (p < 0.001). T1-weighted (T1W) signal and enhanced features resulted in a p value of < 0.05. There were no significant differences in the T2-weighted (T2W) signal and peri-tumoural oedema (p > 0.05). MCM immunohistochemistry showed that all the cases were positive for vimentin (Vim), epithelial membrane antigen (EMA), and the ki-67 index was less than 5%, while all the cases of meningeal Ewing sarcoma/pPNET were positive for Vim and CD99, and the ki-67 index was more than 30%. MRI imaging features of MCMs and meningeal Ewing sarcoma/pPNETs were different. Accurate preoperative diagnosis of these two tumours is helpful in implementing a clinical surgical plan and further management. Moreover, imaging combined with pathology can explain the imaging characteristics better.
Keywords: Ewing sarcoma; Magnetic resonance imaging; Microcystic meningioma; Peripheral primitive neuroectodermal tumors.
© 2020. Belgian Neurological Society.