Solitary Fibrous Tumor of the Orbit

Solitary fibrous tumor (SFT) is an uncommon spindle cell tumor of mesenchymal origin. SFT was first described as a pleural-based mass, but has since been identified in numerous extra-pleural sites including the orbit. Although generally benign, malignant variants have been identified and metastasis can rarely occur [1–3]. Ovoid, wellcircumscribed, lobulated mass on noncontrast CT that may appear heterogeneous and may contain calcifications. MRI of benign lesions shows heterogeneous iso- to hypointensity on T1w and heterogeneous hypo- to iso-intensity on T2w sequences; hyperintense signal on T1 may suggest recent hemorrhage (methemoglobin). Heterogeneous hyperintensity on T2w sequences raises the possibility of cystic degeneration or hemorrhage. Tubular flow-void signals are occasionally seen, representing intra-tumoral vessels. Marked homogeneous or heterogeneous enhancement following contrast administration may have central cystic or necrotic changes in larger or malignant lesions. Regions of restricted diffusion may be seen [1–7].