A case of orbital solitary fibrous tumor

Background: Solitary fibrous tumor is a spindle cell neoplasm that most com monly arises in the pleura and very rarely involves the orbit. Case: A 38-year-old woman presented with slowly progressive proptosis of 3 months duration and optic nerve head edema in her right eye. Magnetic reson ance imaging revealed a well-circumscribed, round mass lesion, which showed isointensity to the gray matter in a T1-weighted image, and variegated int ensity in a T2-weighted image and contact with the optic nerve in her right orbit. The tumor was successfully removed by anterior orbitotomy. Observations: The tumor showed a "patternless pattern" of tumor cell arrang ement, alternating hypercellular and hypocellular areas, a hemangiopericyto ma-like pattern, and thickened strands of collagen. Immunohistochemically, the tumor cells were positive for CD34 and vimentin, and all were negative for other markers of epithelial, neural, muscular, histiocytic, and vascula r endothelial cell elements. The tumor was diagnosed as a solitary fibrous tumor, and the patient was doing well with no evidence of recurrence 15 mon ths after surgery. Conclusions: This case was the 19th reported case of solitary fibrous tumor in the orbital region. CD34 is a highly sensitive marker for solitary fibr ous tumor. Jpn J Ophthalmol 2001;45;412-419 (C) 2001 Japanese Ophthalmologi cal Society.