classification of retinoblastoma

Last reviewed 01/2018

Retinoblastoma can be:

  • familial or sporadic
    • around 94% of newly diagnosed retinoblatomas are sporadic (without a family history of the disease)
    • the remaining 6% are familial
  • bilateral or unilateral
    • the disease is unilateral in 70-75% of patients and bilateral in the remaining
  • heritable or non heritable
    • around 40-50% of cases are hereditary
      • results from germline mutations which can be either a new-onset germline mutation (negative family history) or from a mutation transmitted as an autosomal trait (1,2)
      • typically inherited in an autosomal dominant pattern (2)
      • can manifest as either unilateral or bilateral disease (1)   
    • 50-60% are non hereditary (1)
      • occurs secondary to somatic mutations (2)
      • the tumour always manifests as unilateral disease (1)

All three classification schemes are interrelated (1).

  • bilateral and familial retinoblastomas results from a germline mutation and are thus considered heritable tumours (3)
  • unilateral sporadic disease is usually not considered as a heritable condition
    • around 10-15% of unilateral sporadic cases have a germline mutation while the remaining are caused by somatic mutations (1,3)