Teaching Case

We present a women with progressive visual impairment on the right eye (for years); followed by progressive proptosis and diplopia.

A 73 year old women presented with a longstanding history of right visual impairment (since years) followed by a slowly progressive (6 months) protrusion or bulging of the right globe accompanied by mild eyelid fullness, diplopia and pain in frontal and right orbital regions. Because of progressive symptoms, the women asked for consultation.
Examination confirmed right proptosis, showed right ophthalmoplegia and right optic atrophy. No other anomalies in neurological examination. Neuro-imaging is obviously of importance in the work-up, trying to clarify the aetiology.
Proptosis can result from many conditions including benign or malignant space-occupying lesions of the orbit. A change in visual acuity can result from an anteriorly directed mass effect. In some cases, a compressive optic neuropathy can be the aetiological basis for the visual acuity or field disturbance. Extraocular muscle dysfunction and the resultant diplopia can be secondary to extraocular muscle impingement.
The patient underwent CT and MR that showed a common orbital intraconal mass. The mass was removed and histopathology proved that it was a cavernous hemangioma.

Orbital cavernous hemangiomas are the most common benign masses in the adult orbit and the most common retrobulbar lesions in adults, after inflammatory pseudo-tumour and lymphoma. They are also considered as intraconal masses without optic nerve involvement (differential diagnosis of optic nerve sheath meningioma and optic nerve glioma). They consist in venous malformations of the orbit characterized by dilated, endothelial-lined vascular channels, with a variable amount of fibrous septations and a peripheral fibrous firm capsule. Because the blood flow within these vascular spaces is essentially stagnant, thrombosis is common, but spontaneous bleeding is rare. This is in distinction to cavernomas in the brain. They grow by thrombosis and subsequent recanalization of thrombosed sinusoids.
They predominate in young to middle-aged women, but ranging from 10 to 60 years. Patients usually present with slowly progressive painless unilateral proptosis, but can also have diplopia, visual impairment and increased intra-ocular pressure with large lesions. They are almost always intraconal (80%), with extraconal malformations being uncommon. Is a well defined mass and may enlarge with a Valsalva maneuvre or during pregnancy.
According to the grading system of vascular orbital lesions (1999, Orbital Society), cavernous hemangiomas are classified as type 3 - arterial flow lesions. They are considered low-flow AVM with small-caliber feeding arteries. However, these lesions are not easily identified at angiography. Support for an arterial supply is the fact that the majority of cavernous malformations arise in the lateral intraconal orbit in the area of the posterior ciliary artery.
The major role of MR in the evaluation of cavernous hemangiomas is to provide the precise anatomic delineation of the mass and its relationships to the optic nerve and other orbital structures. These lesions are surgically curable because they are encapsulated and do not recur if completely removed.
The differential diagnosis often includes a cranial nerve schwannoma because cranial nerves III, IV, V and VI have branches within the orbit. Both conditions are well-defined masses, hyperintense on T2-weighted images and enhance. It was shown on dynamic scanning that cavernous hemangiomas begin with a central spot or point of enhancement, which spreads peripherally (the contrast enters these lesions slowly, images obtained after injection usually show minimal or heterogeneous enhancement; it is more uniform on more delayed images), whereas orbital schwannomas usually enhance initially on the periphery. Both may remodel adjacent bone. If an intralesional (hyperintense on T2-weighted images) flow void is seen on T2-weighted images, another diagnosis should be considered, such as vascular hemangiopericytoma, venous varix, or an arteriovenous malformation.
Other masses that can occur in the orbit may be considered in differential diagnosis. Hemangiopericytoma is an uncommon vascular neoplasm with similar appearance (but with margins less well-defined) in neuroimaging studies, such as intense enhancement after contrast. Nevertheless, they are local aggressive and can destroy boneto extend beyond the orbit. Metastases can also occur, with a dense homogeneous stain in angiography. Orbital varix is also a vascular mass, uniformly enhancing, and distensible with Valsalva maneuvre.