A Clinicopathologic Study of Seven Cases of Orbital Solitary Fibrous Tumours

Objective To describe the patient demographics, clinical findings, investigations, surgical outcomes, and histopathological findings of seven cases of orbital solitary fibrous tumours. Method This was a retrospective review of seven cases of orbital solitary fibrous tumour, which were followed up in Hospital Serdang, a national oculoplastic centre, from years 2008-2017. Results This study included seven patients with ages between 21 and 35 years old; two were males and five were females. All seven patients presented with painless chronic unilateral proptosis. Radiological imaging of the orbit showed a localized contrast enhancing intraorbital mass. All patients underwent orbitotomy and excisional biopsy. Intraoperative findings showed a well-encapsulated and vascularized mass. Histological findings of spindle-shaped cells were noted. All cases had positive staining for cluster of differentiation (CD) 34, five were positive for CD 99, four were positive for B-cell lymphoma (BCL-2), and five patients had positive staining for S-100. Three of the patients did not have clear margins during the primary operation and subsequently had a recurrence within two years. Conclusion A solitary fibrous tumour is a rare mesenchymal tumour with a pleural origin. The orbit is the most common extrapleural site of the tumour and they are usually benign. Immunohistochemistry is important to differentiate it from other, more aggressive forms of orbital tumours. Regular follow-up is important to monitor for recurrence.