Vascular Lesions of the Orbit: More than Meets the Eye

Abstract

Vascular lesions of the orbit may be classified on the basis of their natural history, growth pattern, and histologic composition as capillary hemangiomas, venous vascular malformations, venous lymphatic malformations, arterial and arteriovenous lesions, or neoplasms. Most follow a characteristic pattern of clinical development and have one or more specific imaging features that allow diagnosis. Hemangiomas typically manifest at or soon after birth and subsequently involute. They are nonencapsulated, poorly circumscribed, often lobulated, and largely extraconal in location. Cavernous malformations are septate and well circumscribed, may exhibit progressive enhancement on delayed images, and do not involute. Orbital varices appear distended on images obtained with the patient prone or during the Valsalva maneuver. Venous lymphatic malformations show multiple fluid-fluid levels, enlarge during viral infections, and may manifest as chocolate-colored cysts after an acute hemorrhage. Arteriovenous malformations, fistulas, and aneurysms have typical angiographic features. Hemangiopericytomas arise from the paranasal sinuses and show early tumor blush and persistent staining on angiographic images. Hemangioblastomas appear as enhancing mural nodules with associated cysts and serpentine flow voids on magnetic resonance (MR) images. Choroidal hemangiomas and melanomas can be differentiated on the basis of their appearances on T2-weighted MR images. Patients with vascular orbital and ocular metastases commonly have a history of breast or lung primary tumors.

Coexistence of Cavernous Hemangioma and Other Vascular Malformations of the Orbit

“…Internal septa are visible within larger lesions. Cavernous malformations demonstrate progressive accumulation of contrast material on late phase dynamic images and delayed images; contrast material does not fill the central part of the lesion until the late venous phase 32 . Differential diagnosis of cavernous hemangioma includes orbital varices, also known as orbital venous anomalies.…”

“…They result from a congenital weakness in the postcapillary venous wall, leading to the proliferation of venous elements and massive dilatation of the valveless orbital veins 31 . On imaging, orbital venous malformation presents as an intraconal, well-defined, triangular configured mass, tapering toward the apex, with highly intense, homogeneous contrast enhancement 31,32 . The first case we described here had the peculiar findings of the coexistence of cavernous hemangioma and a varix.…”

“…Because of the inaccessibility of the small feeding arteries and the multiple collateral pathways available for recanalization, embolization therapy is not often performed 31,32 . After surgical removal, orbital cavernous hemangiomas do not usually recur.…”

“…The use of contrast material does not typically provide significant additional information, but an absence of enhancement is indicative of a lymphatic component. Fluid-fluid levels produced by hemorrhages of various ages within multiple cysts are almost pathognomonic 32,33 . AVMs involving the orbit are rare and typically manifest with periorbital swelling, dilated retinal veins and epibulbar vessels, visible or palpable pulsations and an audible bruit.…”

“…CT and MR with standard and angiographic protocols can help diagnose these lesions 34 . However, conventional catheter-based angiography typically is required for precise definition and treatment planning 32,35 . Our experience indicates that the coexistence of cavernous hemangiomas and other vascular orbital lesions is a fairly frequent event, never previously well-documented.…”