23 - Retinoblastoma

Abstract

This chapter gives a synoptic view of classification, epidemiologic data, pathology, clinical features, diagnostic procedures, staging, and treatment of retinoblastoma. It is a malignant tumor of the embryonic neural retina frequently affecting young children under the age of 5 years. Tumors may be unilateral or bilateral, unifocal or multifocal. There are hereditary and nonhereditary forms of the disease, and the disease can be sporadic or familial. It is the paradigm for a genetically inherited cancer and provides the basis for Knudson's two-hit hypothesis of carcinogenesis. There are three overlapping methods for classifying retinoblastoma such as laterality, focality, and genetics. The tumor is composed mainly of undifferentiated anaplastic cells that arise from the nuclear layers of the retina. Histology shows similarity to other embryonal tumors of childhood, such as neuroblastoma and medulloblastoma, including features such as aggregation around blood vessels, necrosis, and calcification. The clinical features are leukocoria, strabismus, decreased visual acuity, inflammatory changes, hypema, and vitreous hemorrhage. The diagnosis is carried out by screening, and intraocular and extraocular extent of retinoblastoma. The standard staging system for intraocular retinoblastoma is not truly a staging system, but rather a grouping system and is the Reese–Ellsworth classification. The initial therapy is dependent on both the intraocular and extraocular extent of the disease. Therapeutic modalities include the following and a combined modality approach: systemic chemotherapy, external beam radiotherapy, local ophthalmic therapy, and enucleation. This chapter closes with the posttreatment management and future prospective of retinoblastoma.