Published online by Cambridge University Press: 20 August 2009
The ocular tumours discussed in this section include retinoblastoma, haemangioblastoma, optic nerve glioma, meningioma and melanoma. Ocular rhabdomyosarcoma is discussed with rhabdomyosarcoma of other sites on pages 136 and 137. Genetic disorders associated with significant ocular manifestations (neoplastic and non-neoplastic) include neurofibromatosis type 1 (NF1), neurofibromatosis type 2 (NF2), von Hippel–Lindau (VHL) disease, tuberose sclerosis and familial adenomatous polyposis (see Part Three).
Retinoblastoma is the commonest malignant ocular tumour of childhood and affects 1 per 20 000 children. The tumour is derived from primitive retinal cells (retinoblasts) and usually presents in early childhood (90 per cent before the age of 5 years). Less than 10 per cent of children with retinoblastoma have a positive family history (where inheritance is autosomal dominant), but new mutations are frequent and approximately 40 per cent of retinoblastoma patients have a genetic predisposition. Retinoblastoma holds a unique place in human cancer genetics as the paradigm of the tumour suppressor gene.
Retinoblastoma typically presents as leukocoria (white eye, cat's eye reflex) or strabismus. It is bilateral in about 30 per cent of cases, and these children have a younger age at diagnosis (mean 8 months) than those with unilateral tumour (mean 25 months). Bilateral or multifocal tumours occur in patients with germline mutations of the retinoblastoma (RB1) gene, but about 15 per cent of children with a single tumour will have a germline mutation.
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