This is a retrospective review of 21 patients diagnosed with solitary fibrous tumour of the orbit between 1996 and 2018 at a single centre. The authors reviewed the clinical presentation, management and course of the disease and reanalysed the histopathology looking specifically for the presence of CD34 and STAT6 (signal transducer and activator of transcription 6) markers on immunohistochemistry. The mean age was 48 years (range 14-84) with an equal male to female ratio. Most presented with a slow onset painless periorbital fullness or proptosis and six had diplopia. CT and MRI imaging showed well-circumscribed enhancing masses usually in the extraconal space and in the superior orbit. One patient had diffuse malignant disease requiring exenteration, but the other 20 underwent local excision, three of which had increased mitotic activity on histology suggesting malignant disease. Average follow-up was 60 months, with six patients developing recurrent disease between three and 54 months later. All 21 specimens were CD34 positive, and all of the 20 tested for STAT6 were positive. STAT6 has a high specificity and sensitivity for solitary fibrous tumour. The authors advise that complete excision is the preferred management, but concede that in 24% of their cases the tumour could only be removed piecemeal due to fragmentation, and positive surgical margins were left in a third of patients. Of the six who had recurrent disease, four had further surgery and two were observed, but none developed distant metastases or died of their disease. This is the largest published series to date of orbital solitary fibrous tumour and provides valuable insights into the diagnosis and management of this challenging entity.
Diagnosis and management of solitary fibrous tumour
Reviewed by James Hsuan
Solitary fibrous tumor of the orbit: A case series with clinicopathologic correlation and evaluation of STAT6 as a diagnostic marker.
