Extra-Pleural Solitary Fibrous Tumor:CT and MRI Findings with Corresponding Pathological Basis

Objective To analyze the CT and MRI findings of extra pleural solitary fibrous tumor( ESFT) and to improve the understanding and diagnostic ability prior to surgery. Methods CT,MRI and pathological findings were retrospectively reviewed in 12 patients with ESFT proved by operation and pathology. Results The tumors were found in head in 5 cases,pelvic region in 5 cases,and retroperitoneal region in 2 cases. Eight cases were found on CT scan,among which there were 6 benign lesions,presented with well defined round or elliptic margins; 2 malignant lesions with unclear and invasive margins. All of the eight tumors showed heterogeneous masses with patchy,necrotic foci. Contrast enhanced CT images showed marked,heterogeneous enhancement and progressive enhancement in all lesions. On unenhanced MRI,the lesions presented isointensity on T1WI,hyper or isointensity on T2WI in 3 lesions,multiple cystic hypointense and hyperintense signal in one lesion. On contrast enhanced MRI,solid parts of the mass showed intensive enhancement. Immunohistochemical staining showed that Vimentin positive was 100. 0%,CD34( 100. 0%),Bcl 2( 80. 0%),CD99( 71.4%),as well as negative S 100( 100. 0%),SMA( 100. 0%),and CK( 83. 3%). Conclusion CT and MRI findings of ESFT have certain characteristic findings,especially heterogeneous masses with progressive enhancement on CT scan,hypointense signal on T2WI and strongly enhancement on contrast enhancement MRI scan.