[Solitary Fibrous Tumours/Hemangiopericytomas of the Maters(Meninx):A Clinicopathologic Analysis].

To study the clinicopathologic characteristics,immunohistochemical features,differential diagnosis,and prognosis of solitary fibrous tumours(SFT)/hemangiopericytomas(HPC)in the maters(meninx). Methods A series of 7 cases previously diagnosed as SFT/HPC at the Department of Pathology,Peking Union Medical College Hospital,during the period from 2008 to 2018 were analyzed for clinical data,histopathology,and immunohistochemical findings.The patients were followed up and the relevant literatures were reviewed. Results These seven patients included two males and 5 females aged 22 to 77 years(mean,49 years).Headache was the most common symptom.The magnetic resonance imaging of SFT/HPC showed irregularly contoured masses and dural tail sign was observed at the periphery of the lesion in 4 cases.The major axis of the tumor ranged from 1.8 cm to 10 cm(mean,4 cm).The tumors were located in the mater in 6 cases and in the spinal meninx in 1 case.The tumors were surgically removed in all cases.Under light microscope,the tumors were formed by long round,oval or spindle cells,with rich branching vascular pattern and varying quantity of collagenous fibers bands in both sparse areas and dense areas.According the WHO classification,2 cases were in WHO grade Ⅰ,2 cases in WHO grade Ⅱ,and 3 cases in WHO grade Ⅲ.Immunohistochemistry of the paraffin-embedded tissues in all cases showed positive immunoreativity for CD34 and vimentin in all seven cases,along with positive signal transducer and activator of transcription 6 in 4 cases,negative epithelial membrane antigen and S-100 in 7 cases,and negative progestational hormone and somatostatin receptor 2 in 6 cases.The Ki-67 index ranged from 1% to 15%.Five patients with follow-up data(including 1 current case)were alive,while 2 patients were lost to follow-up. Conclusions The SFT/HPC are rare in the maters(meninx)and is clinically difficult to be differentiated from other meningioma.The combination of CD34 and signal transducer and activator of transcription 6 helps to diagnose this disease.