[Clinicopathological observation of solitary fibrous tumor of the orbit].

OBJECTIVE: To study the clinicopathological characteristics of orbital solitary fibrous tumor. METHODS: It was a retrospective case series study. The clinical and pathological characteristics of 8 cases of orbital solitary fibrous tumor that were treated in Tianjin Eye Hospital from January 2003 to December 2011 were reviewed and analyzed. Immunohistochemical staining was performed, investigating the expression of CD34, vimentin, S-100 and SMA. RESULTS: In the 8 cases, 5 cases were male and 3 cases were female; 6 cases involved the right orbit and 2 cases involved the left orbit. Patients' ages ranged from 30 to 60 years, and the mean age was 41 years; duration of symptoms ranged from 2 months to 5 years. The locations of the tumor were in the superior or superotemporal orbit (5 cases), lacrimal sac and medial orbit (2 cases), or inferior orbit (1 case). The clinical features mainly included the swelling of the upper lid, unilateral painless orbital or lacrimal sac mass, proptosis and diplopia. CT scan usually revealed a moderately or intensely enhanced mass that was well-circumscribed. Complete tumor removal was performed in all cases. The tumor sizes ranged from 1.2 - 3.1 cm and appeared as a round or irregular oval mass with a thin fibrous capsule; incomplete capsule was found in 3 tumors. Microscopic observation revealed that the tumor was composed mainly of spindle or oval cells in a fascicular, storiform, hemangiopericytoma-like or a "patternless" pattern, with numerous thick bands of collagen that showed diffuse positive staining for CD34 and vimentin. Five cases had been followed-up from 6 to 86 months postoperatively, no evidence of local recurrence had been found in these patients. CONCLUSIONS: Orbital solitary fibrous tumor is a spindle cell tumor with diffuse positive staining for CD34 and vimentin. This tumor usually is well circumscribed and encapsulated. Complete excision is the preferred treatment. The tumor should be distinguished from other spindle cell tumors in the orbit.