A Rare Case of An Atypical Solitary Fibrous Tumour of Orbit.

Solitary fibrous tumours are of mesenchymal origin and comprise of uncommon spindle cell neoplasias. Most commonly the lesions arise from pleura but other rarer sites include lungs, peritoneum, pericardium, nasal cavities, thyroid, parotid gland and orbit. We report the case of a 41-year-old male patient who presented to us with a painless, progressive growth of a mass in the superior part of left orbit with proptosis and inferotemporal displacement of the left eye. Computed Tomography (CT) scan revealed homogeneous enhancing lesion in the superior compartment of left orbit in the extraconal region, extending intraconally and distorting the globe. Upon imaging, the differential diagnosis were lacrimal gland tumour, atypical cavernous haemangioma and nerve sheath tumour. Surgical treatment included complete excision of the mass with the intraoperative finding of mass extending upto the superior oblique tendon, a part of which was excised. Histopathological examination revealed CD34 positive, Bcl-2 and MIC-2 positive tumour with the diagnosis of a solitary fibrous tumour with atypical features but no malignant features. After a follow-up of 18 months, no recurrence was detected.