Radiology (March) 146:629-642,1995
Retinal hemangioblastomas (RHb) are among the most frequent and earliest detected lesions associated with VHL. They have been called "retinal angiomas" and "retinal hemangiomas" but hemangioblastoma is the preferred term since they are histologically identical to lesions found in the CNS.
Between 45 to 59% of patients with VHL exhibit RHb (2,4,9,18). About 50% of cases have bilateral RHb (17). RHb have been diagnosed in one and two year olds but only about 5% of cases are discovered before age 10 (4,33). New lesions may develop within two year intervals so frequent monitoring is important (12).
Histologically, the RHb is composed of extensive vascular channels lined by cuboidal endothelial cells. Foamy stromal cells and pericytes comprise the remainder of the tumor (34). The lesions are usually peripheral in the retina but can involve the optic disc or ora serrata directly. A dilated feeding artery and vein is typically present and microaneurysms can be seen (35). Tiny peripheral microangiomas can also be seen in VHL, but are not by themselves, diagnostic.
The RHb are usually asymptomatic if peripheral but if they become large or if they are located centrally, they can cause profound vision loss. Arteriovenous shunting and leaky capillaries lead to exudation of fluid (4). Complications due to hemorrhage include retinal detachment, macular edema, glaucoma, cataract, uveitis, and sympathetic ophthalmitis (4,8). Glaucoma or severe pain can be an indication for enucleation (17,36).
Screening consists of direct or indirect ophthalmoscopy at a minimum. Moore et al recommend the routine use of fluorescein angioscopy for detecting small lesions and reserve formal fluorescein angiography for documenting the size of small RHb (37). Periodic tonometry to exclude glaucoma is also recommended (2). Only large retinal lesions will be seen on contrast enhanced MRI and CT scans (Figure 5). Generally, if the lesion is visible on an imaging study it is already at an advanced stage and vision is severely impaired. RHb can calcify or even ossify at later stages (8).
Figure 5. MR depicting retinal hemangioblastomas and an endolymphatic sac tumor.
a) Precontrast T1 weighted MRI demonstrates a small left eye and high signal
intensity foci in the epidural space adjacent to the expected location of
the endolymphatic sac (arrow). b) Post contrast T1 weighted MRI demonstrates
intense enhancement of both the eye and the endolymphatic sac tumor. c.)
CT through the petrous ridge demonstrates bone erosion at the site of the
endolymphatic sac tumor, typical of the locally aggressive behavior of this
tumor (curved arrow).
Treatment consists of the aggressive use of laser photocoagulation and is often successful in preventing blindness if RHb is diagnosed and treated early. After lesions have enlarged and bled, however, photocoagulation may not help the patient recover vision but it may delay further vision loss (4). Cryotherapy has been used for large lesions (4).
RHb is not the only cause of blindness in VHL. Optic nerve and chiasm hemangioblastomas and post neurosurgical damage to the occipital lobe are other causes for vision loss (38).
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