Neurosurgery notes/Tumours/Tumour syndrome/Turcot syndrome

Turcot syndrome

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Tumour syndrome

General

  • is formed from 2 distinct cancer syndrome)
  • Used to be thought as brain tumours with GI polyps and cancers but now is known to have two distinct cancer syndrome

Brain tumour polyposis syndrome 1 (BTP1)/Mismatch repair cancer syndrome

  • Autosomal dominant
  • Reduced penetrance
  • Characterized by
    • Multiple brain tumors (mainly gliomas) and
    • Other malignancies during childhood.
    • >90% present with café-au-lait macules and other dermatologic abnormalities.
    • 30% develop T cell lymphoma by 10 yrs age
    • 100% develop GI cancer by 20 yrs age
  • Caused by biallelic mutations in 1 of 4 mismatch repair genes.
    • MLH1
    • PMS2
    • MSH2
    • MSH6
      • A different condition (Lynch syndrome 1/hereditary nonpolyposis colorectal cancer (HNPCC)) is caused by heterozygous carriers (only one copy of mismatch repair genes affected.
  • Numbers
    • Rare 200 cases reported
    • Under diagnosed
    • Consanguinity inc. risk: south Asian and middle eastern countries

Brain tumour polyposis syndrome 2 (BTP2)/Familial adenomatous polyposis

  • Autosomal dominant
  • Numbers
    • 1% of all colon cancers
    • <1% of medulloblastomas
  • Diagnostic criteria
    • Hundreds to thousands of colonic polyps at a young age
  • Associated with tumours of
    • Brain (mainly medulloblastoma)
    • Benign colonic polyposis and colorectal carcinomas.
    • Other cancers
      • Osteomas (50-90%)
      • Fibromatosis (10-15%)
      • Thyroid cancer (2-3%)
      • Hepatoblastoma (1%)
  • Due to heterozygous germline mutations in the APC tumor supressor gene (5q21) → activation of the wnt signalling pathway