SOLITARY FIBROUS TUMOR OF THE ORBIT

Solitary fibrous tumor (SFT) of the orbit is a very rare lesion that m ay be misdiagnosed as fibrous histiocytoma, hemangiopericytoma, or oth er orbital tumors. We present a 62-year-old man who presented with pai nless proptosis, 20 years following left eye enucleation for a presume d neurofibroma. On T2-weighted magnetic resonance imaging (MRI), a hyp ointense tumor almost filled his entire left orbit. There was no intra cranial extension. The specimen obtained at orbital exenteration was c onsistent with the histologic, immunohistochemical, and electron micro scopic findings of SFT. The tumor was positive for vimentin and CD34 s taining but negative for S-100 protein and epithelial membrane antigen . Only nine other cases of SFT of the orbit have been documented in th e literature. Recognition of SFT of the orbit as a distinct pathologic entity and further follow-up of published cases are needed to determi ne the prognosis of this rare lesion.