Retinal astrocytoma

• Description - this is a rare and benign tumour of the retina ± optic nerve head. Isolated tumours are not usually associated with systemic disease but multiple or bilateral tumours are seen in patients with tuberous sclerosis (occurs in about 50% of these patients) and more uncommonly with neurofibromatosis.
• Presentation^[2] - they are often asymptomatic but the patient may present with leukocoria. It may also present in adolescence.^[3] Examination reveals a sessile yellow-white mass which can be mistaken for retinoblastoma. Later on, this may become calcified. There may be an associated retinal detachment.^[3]
• Management - these are benign and do not require treatment in themselves, although complications such as retinal detachments need addressing.
• Prognosis - these do not affect the vision.^[4]

Retinal capillary haemangioma^[5]

• Description - this is a rare (~1:50,000 live births), nonmalignant but sight-threatening vascular hamartoma of the retinal or optic disc vasculature. It may be solitary or there can be multiple lesions. The former may occur in isolation (von Hippel disease) but about half of them occur in the context of systemic disease - von Hippel-Lindau syndrome (VHL). All patients with multiple lesions have systemic disease. As there is an inherited component of VHL, if there is a single ocular lesion and a positive family history, the patient is deemed to have VHL. Various types of haemangiomas can occur:^[4]
  • Capillary haemangioma (by far the most common presentation): small well-defined orange-red nodules with associated dilatation and tortuosity of overlying vessels.
  • Exophytic haemangioma: sessile, ill-defined lesion associated with retinal oedema and haemorrhage ± retinal detachment.
  • Optic nerve head haemangioma.
• Presentation^[4] - second to third decade: these lesions may be asymptomatic and picked up on routine screening or may present with visual impairment - more so in exophytic and optic nerve head haemangiomas.
• Management - very small lesions may be managed conservatively but very closely monitored. Otherwise, treatment options include photocoagulation, cryotherapy or brachytherapy. Radiotherapy or surgical excision may also be considered.^[3] Treatment with anti-vascular endothelial growth factor is emerging as a promising option, although it is early days and there has yet to be more research into both safety and efficacy.^[6] Vitreoretinal surgery may be required where severe haemorrhage has occurred.
• Prognosis - this depends on the size and location of the lesion but generally is frequently poor with more than 25% having complete visual loss of the affected eye. There are associated complications which adversely affect visual outcome. These include macular oedema, epiretinal membrane formation, retinal detachment and vitreous haemorrhage.

Retinal cavernous haemangioma^[4][7]

• Description - this is a rare, congenital, unilateral vascular hamartoma. In some patients, this is an autosomal dominant inherited condition which is associated with similar lesions of the skin and central nervous system (referred to as neuro-oculocutaneous phacomatosis or cavernoma multiplex).
• Presentation - second to third decade (females more than males): usually this is a chance finding but, occasionally, patients present with decreased vision secondary to a vitreous haemorrhage. Examination varies from small lesions that look a little like background diabetic retinopathy, to large vascular tortuosities which may show a fluid level within them as the red cells sediment because of the sluggish flow of blood.
• Management - this is usually managed conservatively^[3] although a large, non-resolving vitreous haemorrhage may require a vitrectomy (removal of the vitreous).
• Prognosis - there is a variable outlook for patients with extensive lesions but most patients with localised pathology retain good vision.

Retinal racemose haemangioma^[4]

• Description - this is a rare, usually unilateral, congenital arteriovenous malformation resulting in a direct communication between arteries and veins without an intervening capillary bed. This results in dilated, tortuous fundal vessels. Wyburn-Mason's syndrome refers to a subgroup of these patients who have an associated lesion in the ipsilateral midbrain. In some instances, there are also lesions in the maxilla, mandible, orbit and facial skin.
• Presentation - this is usually a chance finding although there may be visual impairment.
• Management - no treatment is available for retinal lesions but intracranial ones may be managed with surgery, radiotherapy or embolisation.^[3]
• Prognosis - these vessels may occasionally result in haemorrhages if very large. Otherwise, there is neither deterioration nor improvement of vision. Wyburn-Mason's syndrome can be associated with irreversible neurological changes, stroke and death.

Retinal vascular proliferative tumour^[8]

• Description - this is a rare tumour involving the glial cells and the vessels and is characterised by single or multiple nodules on the retinal surface. It usually occurs in healthy patients and is often mistaken for other pathologies (eg retinal angiomas or amelanotic choroidal melanomas). However, in 25% of cases, it arises as a complication of other ocular disease such as retinitis pigmentosa, uveitis, retinal detachment, congenital toxoplasmosis, and Coats' disease.
• Presentation - (most commonly) fourth to sixth decade: blurring of vision ± floaters ± photopsia (flashing lights).
• Management - observation (small, uncomplicated peripheral lesions), cryotherapy, laser photocoagulation or brachytherapy. Occasionally, vitreoretinal surgery is required.
• Prognosis - this varied between patients and may be non-progressing (or slowly progressing) in some patients and rapidly progressing in others. There is a guarded visual prognosis. There are a number of complications that can further limit the outlook: haemorrhage, exudation, macular oedema and retinal detachment.

Tumours of the retinal pigment epithelium

• Congenital hypertrophy of the retinal pigment epithelium (CHRPE)^[4] - this is a common benign lesion occurring in about 1% of the population.^[3] It is a proliferation of the retinal pigment epithelium associated with a hypertrophy of their melanin granules. It is said to be typical or atypical.
  • Typical CHRPE - these may be solitary or grouped lesions which show various pigmentation patterns. These need to be clinically distinguished from melanoma.
  • Atypical CHRPE - these multiple, haphazardly placed lesions show variability in size and degree of pigmentation. These are bilateral.^[3] They may be associated with familial adenomatous polyposis, Gardner's syndrome and Turcot's syndrome.
  Typical lesions are simply observed over time. Individuals with atypical lesions need a prompt investigation of their family history for bowel disease.
• Retinal pigment epithelium adenoma^[9] - this is an unusual and benign condition and presents as a black lesion. It is monitored and managed conservatively.
• Retinal pigment epithelium adenocarcinoma^[9] - this is an extremely rare condition which, up until now, has not been found to spread beyond the eye. It is more documented in females and tends to present as a prolonged inflammation of the eye. Atypical choroidal melanoma was the initial diagnosis in almost all cases. Treatment is with enucleation of the eye.
• Combined hamartoma of the retinal pigment epithelium and retina^[3] - this is a rare, usually unilateral malformation involving the retinal pigment epithelium, the retinal astrocytes and retinal vasculature. It tends to affect males and is found more commonly in patients with neurofibromatosis-2 (occasionally neurofibromatosis-1). It presents with decreased vision, floaters and leucocoria.
• Hamartoma of the retinal pigment epithelium^[4] - this is an uncommon, well-circumscribed, jet-black lesion usually found at the macula.