Description
Wyburn-Mason syndrome is one of the phakomatoses (“birthmarks”), the congenital or heritable conditions characterized by hamartomas and/or neoplasms throughout the body. The other phakomatoses include Neurofibromatosis, Sturge-Weber syndrome, Tuberous sclerosis, ataxia-telangiectasia and Von Hippel Lindau syndrome. Wyburn-Mason syndrome is not hereditary.
Wyburn-Mason syndrome is a very rare, congenital and usually unilateral syndrome characterized by arteriovenous malformations (AVMs) of the retina and central nervous system. Within the AVMs, arteries and veins communicate directly without an intervening capillary bed. In other words, there is a congenital direct connection between the arterial and venous systems. Similar lesions often exist within the orbit, periorbital soft tissues and bones, and the optic nerve and chiasm. Arteriovenous anastomoses may also be present, characterized by more subtle alterations in the capillary and arteriolar networks.
Visual loss in this syndrome may result from retinal or vitreous hemorrhage, reduced perfusion to the rest of the eye (‘vascular steal’) or intracranial bleeding. Central nervous system involvement may also result in other neurological deficits or seizures.
Note: not all patients with retinal AVMs develop extraretinal AVMs; and only those with both retinal and central nervous system AVMs are diagnosed with Wyburn-Mason syndrome. The AVMs are sometimes described as ‘racemose hemangiomas’; this is technically inaccurate.
Symptoms
Wyburn-Mason syndrome is usually diagnosed in a young adult with reduced vision in one eye. Although the AVMs are present at birth, they tend to develop throughout the first few decades of life, with corresponding progression of symptoms and increased risk of bleeding. The diagnosis may also be made incidentally.
Signs
Retinal examination reveals hugely dilated, tortuous retinal blood vessels, with arteriovenous communications. There are no signs of exudates, unlike Retinal Capillary Hemangioma or Retinal Telangiectasia (Coats’ disease). Other signs depend on the location and size of extraretinal AVMs, and include proptosis, ocular motility defects, homonymous hemianopia and focal neurological signs.
Prevalence
Very rare (less than 1/100,000).
Significance
May cause severe visual impairment in the affected eye. Central nervous system AVMs may remain dormant, but are potentially life-threatening.
Differential Diagnosis
Retinal Capillary Hemangioma, Coats’ Disease (Retinal Telangiectasia), Von Hippel Lindau
See Also
The other phakomatoses include Neurofibromatosis, Sturge-Weber syndrome, Tuberous sclerosis, ataxia-telangiectasia (conjunctival telangiectasis) and Von Hippel Lindau syndrome
Management
Additional investigations
Intravenous fluorescein angiography highlights the retinal AVM (see figure). Magnetic resonance imaging (MRI) is sensitive at detecting central nervous system AVMs and associated complications. Neurological assessment is indicated in the presence of suggestive symptoms, or when imaging investigations demonstrate central nervous system AVMs.
Treatment
No safe and effective treatment is currently available for retinal AVMs. Some intracranial AVMs are amenable to radiologically guided embolization or irradiation.
Review
Yearly review is appropriate. The patient is warned that dental or facial surgery to the affected side may cause severe bleeding.
Figure 1
Dilated varicose veins extending from the disc below & then temporal to the macula. The vascular ‘steal’ resulted in venous stasis & retinal vein occlusion.
Figure 2
Fluorescein angiogram displays filling of the lesion in the arterial phase of the angiogram.
