Section 24. Neoplastic Disorders >
Part 3. Solid Tumors >
Chapter 461. RetinoblastomaRima F. Jubran and Anna T. Meadows
Topics Discussed: leukocoria; medical oncology; pediatric oncology; retinoblastoma; retinoblastoma, familial ; trilateral retinoblastoma.
Excerpt:"Retinoblastoma (RB) is the most common primary intraocular malignancy
of childhood. Incidence rates vary from 1 in 14,000 to 1 in 22,000
live births, and it is estimated that 300 children develop retinoblastoma
in the United States annually.1 There is no race
or gender predilection. Approximately 80% of children are
diagnosed before the age of 3 years. More than half of patients
diagnosed in the first year of life have bilateral disease compared with
less than 10% of older children. Retinoblastoma (RB) appears to develop only when both alleles
of a tumor suppresser gene (RB1) located on 13q14
are absent or defective. In hereditary RB every cell in the body
inherits one absent or defective gene. During normal development,
a mutagenic "hit" to the remaining normal allele
results in the loss of normal cellular growth regulation and tumor
development.2 In sporadic, nonhereditary RB, a
single retinal cell must receive 2 mutagenic hits to the 13q14 tumor
suppressor gene before RB can be expressed. Point mutations of the RB1 gene
are the most common events. Variable deletions of the long arm of
chromosome 13 are not commonly found in patients with RB and patients
who are developmentally delayed should not be presumed to have the
chromosome 13q deletion syndrome.3,4 ..."
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