Are bilateral cavernous hemangiomas of the orbit rare entities? The role of MRI in a retrospective study.

Cavernous hemangioma is a benign orbital extraocular vascular lesion consisting of large dilated venous channels with fibrous, well-delineated capsule and hemosiderin deposition. Cavernous hemangioma is considered to be almost always unilateral and bilateral cases have been rarely described. The aim of our study is to evaluate imaging characteristics of cavernous hemangioma and evaluate the prevalence of bilateral cases. We studied 14 patients with cavernous hemangioma of the orbit with surgical confirmation. MRI was performed on a 1.5-T unit before and after contrast agent administration. Each MR examination had been retrospectively evaluated in order to define signal patterns, dimensions, location and other main imaging characteristics. In 3 out of the 14 cases studied (21.4%) bilateral cavernous hemangiomas were found. Thirteen masses appeared isointense on T1, two were hypointense, and two heterogeneous. On T2, 12 were hyperintense, 3 were heterogeneous, 1 isointense, and 1 hypointense. Contrast enhancement was inhomogeneous in 5, homogeneous and intense in 12 cases. The size ranged from 3mm up to 21 mm (average 14.57). In four patients also CT scan without contrast administration of the orbits was performed. Bilateral cavernous hemangioma appears to be more frequent than as predicted by the literature. In our opinion the main reason of this incongruence is related to technological advances. Our results could also be related to carelessness of radiologists to inspect the other orbit for possible concomitant lesions, and thus invites to major attention in exploring both orbits for eventual bilateral lesions.