Spindle cell tumour is a type of connective tissue cancer which is characterized by the presence of spindle-shaped cells when seen under the microscope. It commonly occurs in the pleura, lungs, peritoneum, pericardium, liver, kidneys and rarely in the head and neck region.
Solitary fibrous tumour is a visceral spindle cell tumour originating from the mesenchyme and is rarely seen in the orbit. Orbital solitary fibrous tumours (SFT) remains a highly underdiagnosed tumour due to its rare occurrence outside of the pleural sites and its similarity with other spindle cell tumours.
Pathophysiology of Spindle Cell Sarcoma Orbit
Orbital solitary fibrous tumours show mesenchymal and/or fibroblastic differentiation and have a strong and diffuse immunoreactivity to CD 34. They are most commonly seen originating from the pleura and are rarely known to affect extrapleural sites like the orbit.
They are well-circumscribed, encapsulated tumours with cellular and cystic areas. The tumour cells have a characteristic spindle-shaped appearance and are arranged in whorls. Orbital solitary fibrous tumours stain positive for CD 34 and BCL-2 on immunohistochemistry.
Symptoms and Signs of Spindle Cell Sarcoma Orbit
Spindle cell sarcoma of the orbit is a slow-growing, mostly benign tumour presenting with gradual unilateral painless progressive proptosis and pressure symptoms in a middle-aged individual.
It becomes symptomatic after one month to several years after onset and could be associated with visual loss, restriction of eyeball movement, palpable mass or blepharoptosis. The growth of orbital solitary fibrous tumour is usually variable, non-tender, and non-pulsatile.
Diagnosis of Spindle Cell Sarcoma Orbit
Solitary fibrous tumours of the orbit are usually diagnosed using various imaging modalities such as ultrasonography, Computerized Tomography, Magnetic Resonance Imaging, and Magnetic Resonance Angiography. Low reflectivity with moderated sound attenuation on ultrasonography might indicate the presence of a solitary fibrous tumour.
CT scan shows well-circumscribed mass with or without bony remodelling with moderate enhancement. MRI reveals intermediate to moderate intensity mass on T1-weighted images before and after gadolinium while angiography shows a richly vascular tumour with uniform staining.
Diagnosis is confirmed using histopathologic features and immunohistochemical studies.
Treatment of Spindle Cell Sarcoma Orbit
En bloc surgical excision with complete removal of the tumour is the treatment of choice for spindle cell sarcoma of the orbit.
The chance of recurrence leaves room for close clinical follow-up and review surgery, but there is no conclusive evidence supporting radiotherapy or chemotherapy for prevention of recurrence.