Retinal capillary hemangiomas are benign vascular tumors composed of primitive blood vessels in a loose connective tissue stroma. These vessels leak fluid, which may lead to the formation of exudates, hemorrhage and retinal detachment.
At least one quarter of patients with retinal capillary hemangiomas develop one or more associated intracranial or systemic lesions, in an autosomal dominantly inherited condition known as von Hippel Lindau syndrome (VHLS). (See: von Hippel Lindau syndrome).
The most common pathways to the diagnosis are:
- Asymptomatic tumors detected at routine examination, usually in the second or third decade of life.
- Routine screening of members of families carrying the VHLS mutation.
- Symptomatic lesions – most commonly visual impairment from complications of retinal capillary hemangiomas.
Retinal capillary hemangiomas initially appear as small red dots, usually in the mid-peripheral fundus. Over several years, they enlarge to become elevated, yellow-red tumors with a tortuous, dilated feeder artery and draining vein. These feeder vessels are much shorter and less prominent with peripapillary tumors. Rarely, tumors extend outward (i.e., exophytic capillary hemangioma), rendering them less visible at fundoscopy.
Leakage of fluid, lipids and other blood components from larger tumors often results in the accumulation of hard exudates and subretinal fluid in a ring around the lesion. Exudates and edema may also form at the macula, presumably because the retinal pigment epithelial pump is most active in this location, and therefore concentrates extracellular debris. Other complications of advanced tumors include epiretinal membrane formation, retinal detachment (serous, exudative or tractional) and vitreous hemorrhage. Rarely, glaucoma and phthisis bulbi (a shrunken, scarred, opaque and usually blind eye) have been reported in advanced, severe disease.
Retinal capillary hemangiomas are the most common, and often initial, manifestation of VHLS.
Coats’ Disease (Retinal Telangiectasia), Retinal Arterial Macroaneurysm, Retinoblastoma
Von Hippel Lindau Syndrome, Retinal Detachment – Classification.
The prognosis for vision varies with the location, size and complications of the lesion. Treatment is complex. The potential benefits (e.g., resolution of exudates and edema, prevention of retinal detachment and preservation of vision) must be weighed against possible complications (e.g., vitreous hemorrhage, progressive exudation and retinal detachment).
Fluorescein angiography is performed prior to treatment. The tumor fills rapidly with dye, and leaks during the late phase.
Systemic evaluation for possible associated capillary hemangiomas is commonly considered in the presence of multiple retinal capillary hemangiomas, or single hemangiomas in patients with a family history of VHLS. This may include Magnetic Resonance Imaging (MRI), Computed Tomography (CT) scans, screening blood tests and urinalysis. See: Von Hippel Lindau Syndrome.
Genetic assessment for the VHLS mutation may be advisable.
When progression in size or exudation is detected, laser photocoagulation, photodynamic therapy and/or cryotherapy is performed. Should these treatments fail, radiotherapy or local excision may be considered. Lesions within 5mm of the fovea require specialized assessment.
Larger tumors may be treated with diathermy, radiotherapy or surgical resection. Vitreoretinal surgery may be required for persistent vitreous hemorrhage or epiretinal membranes. Visual improvement is unlikely in cases complicated by total retinal detachment or extensive fibrosis.
Small, peripheral lesions may remain stable for many years, and are observed at regular intervals. Ongoing systemic evaluations may also be recommended.
Capillary hemangioma on the temporal margin of the optic disc.