Updated: 7/30/2019

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)
  • 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
  • Prognosis
    • deadly if not treated
      • the tumor expands to fill the eye and destroy the globe
    • > 95% survival with treatment
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
      • 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
 

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