Orbital Cavernous Venous Malformation (Cavernous Hemangioma)
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Orbital cavernous venous malformation (formerly known as cavernous hemangioma) is a benign, non-infiltrative, slowly progressive vascular neoplasm surrounded by a well-delineated fibrous capsule. It is the most common benign neoplasm of the orbit in adults.
Disease Entity
Cavernous venous malformation (cavernous hemangioma) of the Orbit ICD-9 228.0
Disease
Orbital cavernous venous malformation (cavernous hemangioma) is a benign, slowly progressive vascular neoplasm surrounded by a fibrous capsule. It most commonly presents in middle-aged adults (ages 20-40 years) and women are affected more than men. Its location is most often within the muscle cone, lateral to the optic nerve. Treatment is usually reserved for symptomatic patients (diplopia or visual disturbance) and includes surgical excision. Bilateral cavernous venous malformations of the orbit have been rarely reported.
Etiology
Cavernous venous malformation (cavernous hemangioma) is the most common benign neoplasm of the orbit. It is considered a congenital abnormality. There is no evidence to suggest a heritance pattern. It is not a neoplasm in the usual sense, as it is not derived from a single cell, proliferating cell. Instead, cavernous venous malformations are composed of a network of vascular channels separated by fibrous tissue stroma. Growth of the tumor is secondary to budding of vascular channels into surrounding tissue.
Risk Factors
There are no established risk factors for cavernous venous malformations. However, pregnancy has been associated with accelerated growth of pre-existing cavernous venous malformations.
General Pathology
Cavernous venous malformation is an encapsulated nodular mass composed of dilated, cavernous vascular spaces separated by connective tissue stroma. Flattened endothelial cells line the vascular spaces, which are filled with blood. One to five layers of smooth muscle cells surround the vascular spaces. These histopathologic features may also be seen in lymphangioma.
Pathophysiology
Cavernous venous malformation is a congenital abnormality that presents after sufficient growth causes cosmetic or visual disturbance. Growth of the tumor is a result of budding of the vascular channels into the surrounding soft tissue. It has been speculated that a localized, low-grade change in hemodynamics causes opening of new channels allowing for extension of the tumor into the surrounding interstitium. A fibrous capsule forms at the interface of the advancing tumor and the normal neighboring tissue. Surrounding soft tissue is displaced, compressed or occasionally incorporated into the tumor. Symptomatic visual impairment occurs as a result of involvement of the optic nerve, extraocular muscles or surrounding vasculature.
Primary prevention
Cavernous venous malformation is a congenital vascular neoplasm. There is no primary prevention for this disease entity
Diagnosis
The diagnosis of cavernous venous malformation is suspected clinically and confirmed with orbital imaging, most commonly MRI. They most commonly present as solitary, unilateral lesions. However, multiple tumors have been reported, particularly in Blue Rubber Bleb Nevus Syndrome. Rarely, they may present simultaneously with a cavernous hemangioma of the brain. Cavernous venous malformations have also been reported to present as an osseous lesion involving the orbital bones or as a tumor within the lacrimal gland.
Imaging with time-resolved imaging with contrast kinetics MRI (ie. TRICKS) has also been shown to demonstrate highly characteristic flow characteristics to support the diagnosis.
History
The classic history for cavernous venous malformation is an adult, more often a women, in the 2nd to 6th decade of life with slowly progressive, painless proptosis. Patients usually report a gradual onset of symptoms over a period of 6 months to 2 years. Induced hyperopia or optic nerve compression may result in a complaint of decreased vision. Diplopia may also be a feature of the patient’s history due to extraocular muscle restriction. Gaze evoked amaurosis has been reported.
Physical examination
Depending on the size and location of the cavernous venous malformation, exam findings may range from normal to severe axial proptosis with poor vision, elevated intraocular pressure (IOP), motility defects and a relative afferent pupillary defect. Physical exam should include assessment of visual acuity, pupillary reaction,color vision, Hertel exophthalmometry, intraocular pressure, slit lamp exam with fluorescein and dilated fundus exam and visual fields in case of suspected optic nerve compression. A tumor of sufficient size may induce hyperopia or compress the optic nerve causing decreased visual acuity or an afferent pupillary defect. Hertel exophthalmometry will enable the examiner to appreciate small amounts of proptosis. Slit lamp exam with fluorescein instillation should be used to assess for surface irregularities that may occur as a result of incomplete lid closure from proptosis. Dilated fundus exam may reveal optic nerve swelling, choroidal folds or circumscribed compression of the globe.
Signs
The most common signs of cavernous venous malformation include axial proptosis, motility defects and optic nerve swelling. It does not usually produce inflammatory signs.
Symptoms
Patients with cavernous venous malformations usually present with painless, progressive proptosis. As the tumor grows and involves the extraocular muscles, optic nerve and globe, patients will report double vision and decreased vision.
Clinical diagnosis
The diagnosis of cavernous venous malformation may be suspected clinically but is confirmed with orbital imaging. A presenting complaint of proptosis should always prompt a consideration of orbital imaging. Pupillary abnormalities elevated IOP, optic nerve swelling and choroidal folds should raise suspicion of a possible orbital mass.
Diagnostic procedures
Orbital imaging with B-scan, A-scan, computed tomography (CT) and magnetic resonance imaging (MRI) all contribute to the diagnosis of cavernous venous malformation. B-scan ultrasound reveals a smooth, round to oval lesion behind or apposing the globe with moderate to strong sound attenuation. A scan ultrasound exhibits a regular internal structure, high internal reflectivity and moderate to strong sound attenuation. On CT scan, cavernous hemangioma appears as a well circumscribed, homogenous mass slightly hyperdense to muscle,commonly located intraconally. In long-standing lesions, bone remodeling and small foci of calcification may occur. Low vascular flow results in mild contrast enhancement. Coronal imaging is especially important to assess for position of the tumor relative to the optic nerve. MRI images of cavernous hemangioma exhibit a heterogenous signal, due to flow voids within the lesion.
Laboratory test
Cavernous venous malformation is diagnosed radiologically after a thorough clinical assessment.
Differential diagnosis
The differential diagnosis for a well circumscribed, round to oval, solid orbital mass includes: peripheral nerve sheath tumors (schwannoma and neurofibroma), hemangiopericytoma, fibrous histiocytoma, solitary fibrous tumor and melanoma.
Management
General treatment
Management of cavernous venous malformation is dependent on the presence or absence of symptoms. For small, asymptomatic lesions, periodic observation with once or twice yearly pupil exams, visual acuity, color vision, exophthalmometry, dilated fundoscopy, visual fields and CT or MRI studies is appropriate. For larger lesions causing diplopia or visual disturbances, surgical excision is the treatment of choice. There is no current role for radiotherapy.
Medical therapy
Treatment of cavernous venous malformation is via surgical excision. There are currently no medical therapies for the treatment of cavernous hemangioma.
Surgery
The choice of approach to surgical excision of a cavernous venous malformation depends on the location and size of the tumor. Cavernous venous malformations involving the anterior two-thirds of the orbit can be resected via an anterior eyelid, transconjunctival or transcaruncular approach. More posteriorly located tumors may require a lateral orbitotomy. A transcranial approach may be required for lesions involving the orbital apex. A cryoprobe is often used to aid in removal with minimal blood loss. Even large tumors are usually removed easily and completely.
Surgical follow up
Follow-up is similar to that after any orbital surgery. The patient is usually seen in the first week after surgery and then at 1 month. The surgeon should monitor the patient for recurrences if the tumor was incompletely excised.
Complications
Visual loss from injury to the central retinal artery has been reported as a complication of surgery. Blood loss is typically minimal due to the tumors encapsulation. As with any orbital surgery, there is always the risk of injury to extraocular muscles, optic nerve and surrounding adnexal structures.
Prognosis
With complete exicision of the cavernous venous malformation, the visual prognosis is excellent. If the tumor is incompletely excised, recurrences may occur and in some cases are relentless. Hyperopia as a result of mass effect against the posterior globe may persist even after tumor excision.
Additional Resources
- Turbert D, Puente, Jr, MA. What Is Hemangioma? American Academy of Ophthalmology. EyeSmart/Eye health. https://www.aao.org/eye-health/diseases/hemangioma. Accessed March 15, 2023.
References
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4. Orbit, Eyelids and Lacrimal System, Section 7. Basic and Clinical Science Course, AAO, 2020-2021, p. 75-77.
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7. Warner EJ, Burkat CN, Gentry LR. Orbital fibrous histiocytoma mimicking cavernous hemangioma on dynamic contrast-enhanced MRA imaging. Ophthal Plast Reconstr Surg. 2013 Jan-Feb;29(1):e3-5. doi: 10.1097/IOP.0b013e31825412f7.
