A 23-year-old Hispanic female was referred for the evaluation of a funny-looking optic nerve in the right eye.

She reported no ocular problems, but her medical history was significant for headaches that occurred every one to two days in the deep orbital and occipital areas. She took Lexotan (bromazepam, Roche) and Desflam (bumadizona, Merck) for the headaches. Her family medical history was unremarkable.

On examination, best-corrected visual acuity was 20/30 O.D. and 20/20 O.S. Extraocular motility was smooth and full, and confrontation visual fields were full to careful finger counting. Pupils were round and reactive with slight anisocoria, and there was a trace afferent pupillary defect in the right eye.

Slit lamp evaluation was unremarkable. IOP measured 15mm Hg O.U. Dilated fundus examination revealed the presentation shown at right.

Take the Retina Quiz

1. Which of these bests describes the blood vessel pattern in this patients right eye?

a. Venous tortuosity and engorgement.
b. Arteriovenous malformation.
c. Venous beading.
d. Blood vessel sheathing.

2. What is the disease process?

a. Hemangioma.
b. Neovascularization.
c. Genetic disorder.
d. Autoimmune disease.

3. What is the correct diagnosis for this patient?

a. Combined hamartoma of the retinal pigment epithelium.
b. Capillary hemangioma of the retina.
c. Racemose hemangioma of the retina.
d. Retinal telangiectasia.

4. What further testing is warranted?

a. Neuroimaging.
b. Blood pressure measurement.
c. Ultrasonography.
d. Chest X-ray.

5. What is the recommended treatment for this patient?

a. Surgical excision.
b. External beam radiation.
c. Laser photocoagulation.
d. Observation.

Discussion

This striking retinal vasculature in our patient represents an abnormal arteriovenous communication known as racemose hemangioma of the retina, or Wyburn-Mason syndrome. Patients with this condition often have similar vascular malformations elsewhere in the body, namely the central nervous system.

This rare condition generally is unilateral, congenital and nonhereditary. There is no known predilection for race or sex.¹

Retinal manifestations of Wyburn-Mason syndrome include one or more dilated, tortuous arteries that emerge from the optic disc and extend into the retina. There, they form a distinct arteriovenous communication with a similarly dilated vein, as we observed in our patient. The arteriovenous anastomoses exhibit variable alterations in capillary and arteriolar networks.

Visual symptoms depend on the size, extent and location of the abnormal vascular process. Small arteriovenous anastomoses involve only subtle alterations within the capillary system, so patients generally are asymptomatic.

Large racemose anastomoses are characterized by direct artery-to-vein communications and can involve the entire fundus. They typically resembles a bag of worms. Larger anastomoses often involve more severe vision loss.

More advanced retinal lesions also have a higher incidence of central nervous system involvement. The dilated vessels may resemble those of a capillary hemangioma of the retina. However, Wyburn-Mason syndrome exhibits no distinct tumor, exudation or retinal detachment, and the condition is typically nonprogressive. Orbital arteriovenous malformations may be associated with mild proptosis, conjunctival vascular dilatation or a bruit.

Except for fluorescein angiography, ancillary tests contribute little to the diagnosis of racemose hemangioma. Fluorescein angiography exhibits early rapid filling of the arteriole. The fluorescein then passes through the arteriovenous communication back toward the optic disc with a short transit time. Unlike a capillary hemangioma, there is no leakage from the retinal vessels and no staining of the vitreous in the late phases.

Some 81% of patients with retinal arteriovenous malformations have intracranial vascular anomalies.² CNS vascular lesions typically are ipsilateral to the involved eye and often occur in the midbrain. In some cases, retinal lesions may be an extension of an intracranial vessel abnormality that has extended anteriorly along the visual pathway and the optic nerve to the retina.

Neurologic symptoms vary according to lesion size, location and configuration. Patients may exhibit changes in mental status, headaches, seizures, visual field abnormalities and cranial-nerve palsies. A computed tomography scan of our patient was normal, so we concluded that her headaches were an incidental finding.

Other systemic signs include subarachnoid hemorrhage, hydrocepha-lus, gingival hemorrhages secondary to arteriovenous malformations in the maxilla/mandible, and mental retardation. Warn patients about a risk of massive hemorrhage with facial or dental surgery.

The retinal vascular lesions usually remain stable, so there usually is no treatment. The role of laser photocoagulation is unclear; this may be necessary only in rare cases that involve retinal edema. There is no distinct tumor, so external beam radiation is not indicated. Comprehensive neurologic evaluation, including magnetic resonance imaging or CT scans, is indicated to rule out involvement of the central nervous system.

We educated our patient about this disorder, and told her that her mild vision loss will probably remain stable.

Kathryn Nelson, O.D., optometric resident at Bascom Palmer Eye Institute in Miami, wrote this case.

1. Shields JA, Shields CL. Intraocular Tumors: A Text and Atlas. Philadelphia: W.B. Saunders Company, 1992:412-4.
2. Bidwell AE. 2001. Wyburn-Mason Syndrome. www.emedicine.com.
   

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