Orbital solitary fibrous tumor with aggressive behavior. Three cases and review of the literature.

Background: Solitary fibrous tumor (SFT) is a rare spindle cell tumor that arises most often in the visceral pleura; however, a review of the literature shows at least 31 cases occurring in the orbit. Methods: A retrospective case series of three patients with orbital SFT: a 50-year-old man, observed in 1997, with an angioma-like lesion in the upper half of the orbit causing osteolysis of the orbital roof; a 24-yearold man, observed in 1992, with a superotemporal mass in the right orbit occupying the lacrimal gland region, firstly diagnosed as schwannoma, recurring 4 years after dacryoadenectomy; a 70-year-old man, with a retrobulbar mass diagnosed on a biopsy as hemangiopericytoma, recurring and infiltrating the orbital roof 4 years after surgery. Results: A review of the literature and presentation of three cases of SFT which showed infiltration of the orbital roof and/or recurrence. Conclusions: Our cases provide evidence of how orbital SFT can behave aggressively and mimic other orbital tumors, thus making mandatory the consideration of this relatively new entity in common clinical practice as well as careful follow-up. Their aggressive growth is unusual, described in only 6 of the 31 cases so far reported in the literature. Immunohistochemistry is of importance for the diagnosis, since CD34 immunoreactivity is peculiar to SFT.