Vascular anomalies in the orbit: CT and angiographic diagnosis

From a series of 1,615 patients examined radiologically for unilateral exophthalmos, 523 were shown to have a primary mass lesion in the orbit. Of these, 103 were designated as vascular anomalies, exclusive of the haemangiomata which in this series were classified with the benign orbital tumours. Venous malformations were by far the commonest variety of vascular anomalies encountered. They constituted 13.4% of all primary mass lesions in the series and 4.3% of all causes of proptosis. Their typical appearance on venography is described and correlated with the findings on computerized tomography. Other vascular lesions include carotico-cavernous fistulae and arterio-venous shunts in the middle fossa of the skull which cause secondary dilatation of orbital veins and can be diagnosed by a combination of CT scan and venography. Orbital blood cysts in children and intra-orbital arterio-venous malformations are also described in terms of angiography and computerized tomography.