What Is Gestational Trophoblastic Disease?

 

 

A General Overview

Gestational trophoblastic disease (GTD) is a group of rare tumors that lead to abnormal growth of cells inside a woman’s uterus. GTD does not actually develop from cells of the uterus like the case in cervical cancer. On the other hand, these tumors start in the cells would somehow develop into the placenta during pregnancy. 

GTD starts in the layer of cells known as the trophoblast that envelops an embryo. Early in normal development, the cells of the trophoblast create tiny projections called villi. Later these villi develop inside the lining of the uterus. 

 

What are the Types of Gestational Trophoblastic Disease?

The main types of gestational trophoblastic disease include:

  • Hydatidiform mole
  • Invasive mole
  • Choriocarcinoma
  • Placental-site trophoblastic tumor
  • Epithelioid trophoblastic tumor

Hydatidiform mole

Hydatidiform mole is the most common form of gestational trophoblastic disease (GTD), it is also called molar pregnancy. It is formed by the villi that have been swollen with fluid. These swollen villi develop in clusters that seem like bunches of grapes. This is known as molar pregnancy but forming a normal baby, in this case, seems impossible. However, in some cases (less than 1 in 100), a normal fetus can develop with the molar pregnancy. Hydatidiform moles do not cause cancer but they can develop into cancerous GTDs. There are two types of hydatidiform moles: complete and partial.

A complete hydatidiform mole usually develops when one or two sperm cells fertilize an egg cell which does not have nucleus or DNA (known as “empty” egg cell). Surgery can be considered as an option to remove most complete moles. Most often this is an invasive mole, but on rare occasions, it is choriocarcinoma, a cancerous form of GTD. 

A partial hydatidiform mole takes place when two sperm fertilize a normal egg. Partial moles, in general, are totally removed by surgery. However, some women with partial moles could need further treatment after the surgery. The persistent gestational trophoblastic disease is GTD that won’t be cured by surgery. Persistent GTD takes place when the hydatidiform mole has developed from the surface layer of the uterus into the muscle layer below. The surgery is used in order to treat a hydatidiform mole scrapes the internal parts of the uterus. In fact, this removes only the internal layer of the uterus and can not remove tumors that developed into the muscular layer. 

Invasive mole

An invasive mole is a hydatidiform mole that has developed into the muscle layer of the uterus. It can develop from complete or partial moles. It develops in rare cases, actually 1 out of 5 women who have had a complete mole removed. The risk of developing invasive moles in these women increases in the following cases:

  • More than four months between their last menstrual period cycles
  • The uterus becomes very large
  • They are over the age of 40
  • They have had the gestational trophoblastic disease previously

 

As these moles have grown totally inside the muscle layer, they are not totally removed during a D & C. invasive moles can disappear on their own, sometimes, but in general, they need more treatments. 

Choriocarcinoma

A choriocarcinoma is a cancerous form of gestational trophoblastic disease (GTD). it is more likely to happen more than other types of GTD as it grows quickly and spreads to organs from the uterus. Half of all gestational choriocarcinomas begin as molar pregnancies. 

Placental-site trophoblastic tumor

A placental-site trophoblastic tumor (PSTT) is an extremely rare type of GTD that develops where the placenta is connected to the lining of the uterus. This tumor, in general, develops after a normal pregnancy or abortion, however, it may also develop after complete or partial removal of the mole. Most placental-site trophoblastic tumors do not spread to other places inside the body. 

Epithelioid trophoblastic tumor

An epithelioid trophoblastic tumor (ETT) is a very rare type of gestational trophoblastic disease that can be really difficult to diagnose. The ETT used to be known as typical choriocarcinoma because the cells look similar to the choriocarcinoma cells under the microscope but now studies say it is a separate disease.

 

What are the Signs of GTD?

The main sign of GTD is the abnormal vaginal bleeding along with the following signs:

  • Vaginal bleeding not linked to menstruation
  • A large-sized uterus more than expected during pregnancy
  • Pain in the pelvis
  • Severe nausea
  • Vomiting
  • High blood pressure
  • Severe headache
  • Swelling of hands and feet
  • Shortness of breath
  • Dizziness

 

GTD can cause, sometimes, an overactive thyroid and here are the symptoms of an overactive thyroid include:

  • Irregular heartbeat
  • Shakiness
  • Sweating
  • Weight loss
  • Trouble sleeping
  • Movements in bowel frequently
  • Anxiety
  • Irritability

 

Tests and procedures used to detect and diagnose gestational trophoblastic disease

  • Physical examination; an examination of the whole body to detect signs of health problems such as lumps or anything else seems abnormal. 
  • Pelvic examination; an examination of the vagina, cervix, uterus, fallopian tubes and ovaries. A speculum is placed inside the vagina and the doctor checks the vagina and cervix to detect any signs of diseases. 

 

Gestational Trophoblastic Neoplasia

Diagnosis

Gestational trophoblastic disease (GTD) is defined by certain abnormal proliferation of trophoblasts. If they cause invasion, they are known as gestational trophoblastic neoplasia (GTN).

 

High-risk Metastatic Gestational Trophoblastic Neoplasia

The treatment of high-risk metastatic gestational neoplasia may include the following: 

  • Combination of chemotherapy
  • Intrathecal chemotherapy and radiation therapy
  • High-dose chemotherapy to the brain

 

GTD Management 

The main pillar of GTD management is surgery. Partial moles are generally diagnosed on pathology specimens after D & C for missed abortion. On the other hand, complete moles are generally diagnosed by ultrasound then scheduled for surgery. Women with GTD can develop a hysterectomy. They need hCG monitoring later on in the same case with any other GTD as they can still develop metastatic disease after getting the hysterectomy. However, most patients will need to keep reproductive capacity.

Preoperative assessment:

  • A detailed medical history
  • A complete physical examination
  • Group & screen
  • CBC
  • Creatinine
  • Electrolytes
  • LFTs
  • TSH (T4, T3 if TSH abnormal)
  • CXR
  • Pelvic ultrasound

 

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