Retinoblastoma: an overview.

Retinoblastoma, the most common intraocular malignancy of childhood arises due to mutation of the retinoblastoma gene on chromosome 13q14. In the hereditary setting this mutation is present in all germ line cells and can occur as early as during development; however it requires a mandatory second "hit" or mutation of the remaining allele for retinoblastoma to develop. The non-hereditary form arises from spontaneous mutation affecting both alleles in a somatic cell of the retina. The tumor may present with leucocoria or strabismus. The diagnosis is best made by an ophthalmologist who examines the patient under sedation. Although tissue biopsy is not routinely performed, imaging studies like ultrasound and MRI scan can serve as useful adjuncts to help in establishing the diagnosis and also aid in staging. Group A tumors are smaller than 3 mm while group B tumors are >3 mm or those located in the macula. Groups C and D tumors are associated with localized and diffuse vitreous seeds respectively. Group E tumors occupy >50% of the globe and are generally not salvagable. Despite the fact that great advances have been made in the treatment of retinoblastoma in the last two decades, a large number patients undergo procedures associated with significant morbidity such as enucleation. We recommend large multi institutional studies using newer therapeutic models and targeting novel pathways to improve the outcome in advanced stage retinoblastoma.