Retinoblastoma

Definition

Retinoblastoma is a malignant neuroblastic tumor derived from the embryonic retinal cell.

Etiology

Retinoblastoma develops following mutations in both alleles of a cell’s RB1 gene. The RB1 gene is located on the long arm of chromosome 13 (13q14) and produces a nucleoprotein that regulates the transition of a cell from G1 to the S phase of the cell cycle. Loss of both RB1 alleles allows uncontrolled cellular proliferation. In approximately 40 % of patients with retinoblastoma, loss of the first RB1 allele is inherited from either an affected parent (10 %) or from a spontaneous mutation in one of the gametes (90 %), and the loss of the second is spontaneous. In the remaining 60 % of patients with retinoblastoma, loss of both RB1 alleles in the same cell is spontaneous (Murphree et al. 2006; Gass 1997; Shields 1999; Conway et al. 2005).

Clinical Presentation

Retinoblastoma commonly presents as leukocoria (white pupil) or strabismus in a young child. Other less common signs...