Anatomy and Pathology of the Placenta 5

Question 1

What is the definition and mechanism of gestational trophoblastic disease (GTD)? What are the classifications?

Answer 1

• Definition
  
  • heterogeneous group of “proliferative” placental tissue diseases
    
    • maternal tumor arising from fetal tissue
    • trophoblast → beta-hCG is a tumor marker
• Mechanism
  
  • normal control mechanisms fail
  • invasive tumor with local and distant spread
• Classifications
  
  • hydatidiform mole - 80%
    
    • complete
    • partial
  • persistent/invasive GTD
  • choriocarcinoma
  • placental site trophoblastic tumor (rare)

Question 2

What is the clinical presentation of a hydatidiform mole?

Answer 2

• Irregular bleeding 1st or early 2nd trimester
• Uterine size > dates
• Abnormally high hCG titers (>100,000 IU)

Question 3

What are the risk factors for hydatidiform moles?

Answer 3

• Matenral age
  
  • > 35 yo
  • < 20 yo
• Abnormal oocytes susceptible to atypical fertilization

Question 4

What is a hydatidiform mole?

Answer 4

• Cystic swelling of chorionic villi
  
  • “central cisterns”
• Trophoblastic proliferation
• May precede choriocarcinoma

Question 5

What are common features of a complete hydatidiform mole?

Answer 5

• Genetically diploid (DNA all of paternal origin-androgenetic)
• No embryonic development
• Gross finding of grape-like swollen villi involving all or most of the villi
  
  • circumferential trophoblast hyperplasia
  • loss of p57 expression
• atypia present
• 2% are followed by choriocarcinoma
• Elevated serum hCG

Question 6

What are common features of a partial hydatidiform mole?

Answer 6

• Genetically triploid (ie XXY) - extra haploid chromosome set of paternal origin
• Embryo is present but abnormal and rarely viable through term
• Gross finding of grape-like swollen villi involving only some villi, less prominent trophoblast hyperplasia (focal) and preservation of p57 expression
• Rarely followed by choriocarcinoma
• Less elevated serum hCG
• No atypia

Question 7

What are some findings in persistent/invasive GTD? What is the method of diagnosis?

Answer 7

• Local trophoblastic proliferation and invasion
• Villous pattern maintained
• Metastasis rare
• Diagnosis based upon stable or serially rising hCGs after surgical evaluation

Question 8

What are some prominent features of choriocarcinoma?

Answer 8

• Malignant trophoblastic tumor
• Highly angioinvasive
  
  • hematogenous spread to liver, lungs, and brain
• HCG greatly elevated
• Chemotherapy cures most cases even if metastatic
• Half arise in background of hydatidiform mole, others in apparently normal pregnancy or after abortion