Vasoproliferative retinal tumour

Short abstract

Brachytherapy requires further evaluation

Vasoproliferative retinal tumour is an enigmatic disease, characterised by one or more retinal nodules, which are usually located pre‐equatorially and inferotemporally, and which cause retinal exudates, macular oedema, and epiretinal membranes. Numerous single case reports and several case series have been published, with the disease described using a variety of terms.¹,²,³,⁴

The tumour in question consists mostly of glial cells interlaced with a fine capillary network and dilated, hyalinised blood vessels, some of which are occluded.⁵,⁶,⁷ Exudates, macrophages, and foreign body giant cells are also present. The histology does not indicate a “vasoproliferative” tumour. The term “reactionary retinal glioangiosis” has been proposed.⁵

Approximately 75% of cases are idiopathic and 25% are secondary to other ocular diseases, such as retinitis pigmentosa, uveitis, retinal detachment, congenital toxoplasmosis, and Coats' disease.³,⁸ Multiple lesions occur in about 6% of patients without predisposing disease and in 41% of patients with pre‐existing ocular disease.³ Multiple lesions can be bilateral, even in the absence of any apparent underlying ocular disease, especially in females.³ Bilateral vasoproliferative tumours have been reported in a pair of monozygotic twins.⁹ There is no sex preponderance. The condition can present at any age but is usually detected between the ages of 40 years and 60 years. A rare, diffuse variety of vasoproliferative tumour exists, which is relatively aggressive and which tends to occur in young females (mean age 19 years).³

Patients tend to present with visual loss, floaters, and/or photopsia. On ophthalmoscopy, the tumour has the appearance of a yellow or pink, intraretinal mass associated with adjacent hard exudates and occasionally retinal and vitreous haemorrhages. The hard exudates tend to extend posteriorly, eventually involving the fovea. There may also be macular oedema and exudative retinal detachment, which can become total. In advanced stages, there can be neovascular glaucoma. Epiretinal membranes may also develop, which can cause retinal distortion. The natural course of this disease varies from patient to patient, progressing slowly or not at all in some but causing severe ocular complications in others.

Fluorescein angiography shows a rich capillary network and/or telangiectatic blood vessels within the tumour. These leak profusely so that the entire lesion is hyperfluorescent in the late stages of the angiogram. On ultrasonography, vasoproliferative tumours vary in size from 1.0 mm to more than 5 mm, averaging about 3 mm. The internal acoustic reflectivity varies from one tumour to another and can be low, medium, or high. Tumour biopsy may be needed in some patients.

The differential diagnosis includes eccentric disciform lesion, retinal haemangioblastoma, amelanotic melanoma, choroidal haemangioma, and Coats' disease.

Observation is recommended if a small, peripheral lesion is not causing much exudation and if there seems to be no threat to vision.¹⁰ Cryotherapy using the triple freeze‐thaw technique can conveniently be applied transconjunctivally in most cases, but repeated treatment may be required, especially if the tumour thickness exceeds 2 mm.³ As early as 1932, Traquair successfully used brachytherapy to obliterate exudative retinal haemangioblastoma.¹¹ Anastassiou et al have used essentially the same approach for the treatment of vasoproliferative tumours, and in this issue of the BJO (p 447) they report their results with 35 consecutive patients treated with ruthenium plaque radiotherapy. Tumour regression and resolution of the exudation were achieved in 31 patients (89%). The four failures occurred in advanced cases, with total retinal detachment and neovascular glaucoma. After a median follow up of 24 months, the visual acuity was the same as at presentation or better in 20 eyes and only five of the remaining patients had severe visual loss. The main cause of visual loss was cellophane maculopathy.

Vitreoretinal surgery may be required to treat vitreous haemorrhage or an epiretinal membrane. Hard exudates threatening the fovea have also been removed successfully (Groenewald, Damato, unpublished data); however, this treatment requires further evaluation. Advanced disease with exudative retinal detachment and neovascular glaucoma may be treatable by surgical removal of the “toxic tumour.” This approach has proved successful in treating severe exudative and neovascular complications developing after radiotherapy of uveal melanoma.¹²

Photodynamic therapy has recently been shown to be effective.¹³ There is scope for investigating agents such as intravitreal triamcinolone and anti‐angiogenic factors like ranibizumab (Lucentis), bevacizumab (Avastin), and anacortave acetate (Retaane). We can expect several case reports on such novel therapies in the near future and it will be interesting to see whether any will supersede the brachytherapy described in this issue of BJO.