Module 16.2 GTN Flashcards
What is a trophoblast?
The tissue that will become the placenta that attaches to the endometrium to gain access to the maternal circulation
Other than gain access to maternal circulation, what can a trophoblast also do?
- Infiltrate maternal tissues
- Invade vessels
- Be transported to the lungs as an embolism
What is a hydatidiform mole?
A cystic degeneration of chorionic villi in a molar pregnancy (complete and partial molar pregnancies).
What is a molar pregnancy and what are the types?
An abnormal proliferation of pregnancy related to a trophoblast with malignant potential.
- Complete mole
- Partial mole
- Invasive mole
- Choriocarcinoma
What is GTN and what is the most common type?
Gestational Trophoblastic Neoplasia
Most common = Complete molar pregnancy (benign if treated early)
Describe the chromosomes of a complete molar pregnancy and how it occurs?
- 46xx or 46yy (80% of the time)
- 46xy (20% of the time)
- Chromosomes are exclusively from father
An ovum with absent/inactive maternal chromosomes is fertilized by a normal haploid sperm that duplicates and produces a diploid 46xx or 46yy
Or:
An empty ovum is fertilized by 2 haploid sperm to get 46xy
How does a molar pregnancy appear?
No fetus with an extremely abnormal placenta
What are some signs and symptoms of a molar pregnancy? (7)
- Large for dates
- Vaginal bleeding (90%)
- Passage of hydropic villi
- ++hCG serum >100,000 miu/ml, -
- Hyperemesis
- Toxemia or pre-eclampsia before 24 weeks
- Respiratory failure
What is the sonographic feature of a complete molar in the 1st trimester?
Appears like an incomplete abortion
What is the sonographic feature of a complete molar in the 2nd trimester?
Echogenic tissue that expands the endometrial canal with multiple cystic spaces that range in size up to 2cm giving a grape-like appearance
What kind of cysts occur bilaterally 25% of the time with a complete molar due to elevated hCG?
Ovarian theca lutein cysts
What kind of karyotype does a partial molar pregnancy have?
Triploid (69xxx, 69xxy, 69xyy)
What kind of chromosomal makeup does a partial molar pregnancy have?
One set of maternal chromosomes and 2 sets of paternal chromosomes
How does a partial molar pregnancy happen?
Fertilization of a normal ovum with 2 haploid sperm
Describe the pathology of a partial molar pregnancy: (2)
- Abnormal fetus with a triploid karyotype
2. Normal and hydropic placental tissue
What is maternal triploidy?
When one sperm fertilizes an ovum with double maternal info (not a GTN** and not a risk for cancer)
Describe the sonographic features of the placenta with maternal triploidy:
Huge placenta with numerous cystic spaces in a non uniform pattern
How does maternal triploidy appear in the 2nd and 3rd trimester?
Severe asymmetric IUGR fetus, may see hydrocephalus
Describe ‘Diploid-Complete Mole’
No maternal contribution, single sperm fertilization with duplication
Describe ‘Diploid-Dispermy’
No maternal contribution, dual fertilization. Can be XX, YY, or XY
Describe ‘Triploid-Partial Mole’
Dispermy paternal contribution with maternal contribution
Describe ‘Triploid-Triploidy Syndrome’
Diploid maternal contribution
What percent of complete molar pregnancies will be benign?
80%
What percent of partial molar pregnancies will be benign?
95%
What does PTN stand for?
Persistent Trophoblastic Neoplasia
Invasive mole and choriocarcinoma are referred to as what?
PTN (persistent trophoblastic neoplasia)
What potential do PTN’s have?
Malignancy (considered to be the most curable gynecological malignancy)
What percent of molar pregnancies develop into a persistent disease?
20%
In rare cases years after normal term delivery
What is an invasive mole and what is it also known as?
The presence of chorionic villi and proliferating trophoblast deep in the myometrium
AKA: Chorioadenoma Destruens
What is the most common form of PTN?
Invasive mole (80-95%)
What are the stages of an invasive mole?
- Confined to the uterus
- Spread to adjacent organs/vessels
- Embolize to distant sites (lung/brain)
What does choriocarcinoma start as most of the time?
Molar pregnancy and can present after miscarriages, abortions or normal pregnancies occasionally.
What is the histology of invasive mole?
Presence of chorionic villi and proliferating trophoblast deep in the myometrium
What is the histology of choriocarcinoma?
Abnormal proliferating trophoblast with no formed villi
Why is choriocarcinoma able to easily travel from the uterus to other structures?
Because chorionic villi is purely cellular
What are the stages of choriocarcinoma?
- Invades the myometrium
- Invades vessels causing hemorrhage
- Necrosis
- Distant mets
What are the frequent metastasis sites of choriocarcinoma in order of spread?
Lungs, followed by the liver and brain
What are some differentials for PTN? (3)
- Adenomyosis
- Fibroids
- AV malformations
Describe the features of PTN on colour (4) and spectral (2)?
Colour:
- Aliasing due to AV shunt
- Chaotic vasc arrangement
- Lesion looks larger with colour than 2D
- Trophoblastic flow
Spectral:
- Increased PSV >50cm/s (normal = <50)
- Low resistive index (RI) <0.5 (normal = 0.7)
What are other conditions that would have the same high velocity/low impedance type flow like PTN?
- PID
- Pelvic abscess
- Benign and malignant ovarian neoplasia
What helps distinguish between PID, abscess, and ovarian neoplasms from PTN? (3)
- Clinical findings
- Serum hCG **
- U/S appearance
What is non metastatic PTN treated with?
Methotrexate (good prognosis)
High risk metastatic PTN has a pretreatment hCG level of what?
> 40,000 miu/ml
What are the risk factors for a molar pregnancy? (3)
- Advanced maternal age
- Prior molar pregnancy
- Asian ancestry
What is another name for partial molar pregnancy?
Diandric triploidy
What is the treatment for complete and partial mole? (4)
- Induced labor
- D & C
- hCG titer sampling weekly or monthly for a year
- Avoid pregnancy for 1 year
What are the US features of PTN and what scan is used to assess? (5)
EV scan
- Focal echogenic nodule in myometrium
- Grape like cysts
- Hyperechoic/complex lesions
- Bulky, heterogenous uterus
- Tumour may extend to other organs or side walls
What differentiates between diff forms of PTN?
The pathology, not U/S
What are the 2 catagories of metastatic PTN?
- Low risk - cured with chemo
2. High risk
What are the factors of high risk metastatic PTN? (4)
- Having the disease more than 4 months
- Having a pretreatment hCG level > 40,000 miu/ml
- Brain/liver mets
- Poor prognosis
What is the treatment for high risk metastatic PTN? (3)
- Multi-agent chemo
- Radiotherapy
- Surgery
What is Non-Gestational Trophoblastic Neoplasia?
A tumour that produces hCG and can infiltrate into the uterus causing choriocarcinoma
