Solitary fibrous tumor of the orbit with multiple cavities.

Solitary fibrous tumors (SFTs) are rare spindle cell neoplasms of mesenchymal origin that most commonly arise within pleura and have also been reported in many extrapleural sites including the orbit. Cavitary changes within SFT of both pleura and extrapleural sites have been documented, but remain very rare. To the authors' knowledge, the third known case of an orbital solitary fibrous tumor containing large pseudocystic cavities is described. MRI demonstrated a heterogeneous enhancing mass with multiple cavities. Excisional biopsy revealed solid tumor with large cavities filled with straw-colored fluid and tumor cells that stained positive for CD34 and CD99 antigens, consistent with SFT. The patient had an uncomplicated postoperative course with no sign of recurrence and resolution of the proptosis after 12 months of follow up. SFT are rare benign orbital neoplasms that rarely present with cavitary changes. Current treatment options include complete surgical excision, which was performed in this case. Close follow up is advised to monitor for recurrence.