Imaging findings of solitary fibrous tumors

Objective To investigate the imaging characteristics of solitary fibrous tumor(SFT).Methods This study included 11 cases with SFT proved by pathological results.The imaging manifestations were retrospectively reviewed and analyzed in comparison with surgical and pathological results. Among them,8 patients underwent CT plain scan (1/8) or enhanced scan (7/8),4 patients underwent MR plain scan (2/4) or enhanced scan (2/4),and only 1 patient underwent both CT and MR scan.Results ( 1 )SFT were located in the thoracic cavity(2/11 ),abdominal and pelvis(5/11 ),and somatic soft tissues (4/11 ).The average tumor size was 11.8 cm ( 2.5 to 23.0 cm).Among them,4 tumors were round or ellipse,and 7 tumors were irregular.Eight tumors had well-defined contours,and the others showed illdefined contours.(2)On CT scan,all SFTs showed inhomogeneous density with low density areas.Calcification was seen in I case,and hemorrhagic foci were detected in 2 cases.(3)On MR scan,all SFTs showed intermediate signal intensity on T1 WI.Three tumors were slightly hyperintense and the other was hypointense on T2WI.All of them were rich of vascular signal voids.Three tumors,including 2 tumors with scattered long T1 and T2 signal and 1 tumor in the liver with hyperintense haemorrhage,displayed inhomogeneous mixed signal.One tumor in the orbit showed homogeneous signal.(4)On enhanced scan,9 tumors showed irregular enhancement with multiple circuitous vessels in the arterial phase,and continuous or progressive enhancement with patch non-enhanced areas in the venous phase.( 5 ) Histologically,SFTs were composed of juxtaposed hyper- and hypo-cellular spindle cells,dense collagenous stromas and numerous thin-walled blood vessels with a staghorn configuration.Conclusion The possibility of SFT should be considered when a single soft tissue mass with sharp border,inhomogeneous density is detected,especially with inhomogeneous enhancement maintaining in the venous phase. Key words: Fibroma;  Tomography,X-ray computed;  Magnetic resonance imaging