Updated: 12/26/2021

Retinoblastoma

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  • Snapshot
    • A 2-year-old boy presents to his pediatrician for strabismus. Family history is notable for osteosarcoma in his father. Physical examination is notable for strabismus and bilateral leukocoria. He is referred to a pediatric ophthalmologist for further evaluation.
  • Introduction
    • Overview
      • a primary intraocular malignancy arising from the retina
        • 2 forms
          • heritable retinoblastoma (Rb)
            • associated germline mutations in the RB1 gene or de novo germline mutations
            • typically leads to bilateral disease
          • nonheritable Rb
            • associated with somatic mutations in the RB1 gene
            • typically leads to unilateral disease
  • Epidemiology
    • Incidence
      • most commonly affects children (< 5 years of age)
  • ETIOLOGY
    • Pathophysiology
      • RB1 gene encodes a nuclear protein, retinoblastoma, that serves as a tumor suppressor
        • located in chromosome 13
        • does not allow the cell cycle to proceed from the G1 to the S phase
          • via its binding to E2F, a transcription factor
      • loss of the RB1 gene dysregulates the cell cycle and results abnormal cellular proliferation
      • "2-hit hypothesis"
        • there are 2 Rb alleles that encode the tumor suppressor
          • Rb mutation is inherited, affecting the allele of the RB1 gene
          • a second, acquired mutation that affects the second RB1 allele, leads to the development of retinoblastoma
    • Associated conditions
      • osteosarcoma
  • Presentation
    • Symptoms
      • visual loss
    • Physical exam
      • leukocoria
      • loss of/abnormal red reflex
      • strabismus
      • nystagmus
  • Imaging
    • Ocular ultrasonography
      • indication
        • may be performed prior or during ophthalmologic examination under anesthesia
          • can find echogenic soft-tissue mass with variable shadowing
    • Optical coherence tomography
      • indication
        • performed during ophthalmologic examination under anesthesia
        • provides high-resolution images that can detect small tumors, can serve as a screening tool, and identify tumor recurrence
    • MRI Brain and orbit
      • indication
        • imaging study of choice
        • helps determine potential optic nerve involvement, determine the size of the tumor, and if there is an associated intracranial tumor
  • Studies
    • Ophthalmic evaluation under anesthesia
      • indication
        • newly diagnosed leukocoria in a child
        • component of evaluation of retinoblastoma
      • findings
        • chalky and off-white retinal mass
          • has a friable consistency
    • Biopsy
      • contraindicated because of the risk of tumor seeding
    • Genetic testing
      • performed in all cases
  • Differential
    • Cataract
      • differentiating factor
        • ophthalmologic examination will demonstrate opacification of the lens
  • Treatment
    • Medical
      • local and systemic chemotherapy
        • indication
          • a first-line therapeutic option
    • Surgical
      • laser photoablation
        • indication
          • a first-line therapeutic option
      • radioactive plaques
        • indication
          • a first-line therapeutic option
      • cryotherapy
        • indication
          • a first-line therapeutic option
      • enucleation
        • indication
          • a first-line therapeutic option
  • Complications
    • Metastatic disease
    • Blindness
  • Prognosis
    • Deadly if not treated
      • the tumor expands to fill the eye and destroy the globe
    • > 95% survival with treatment
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