Placenta
Gestational trophoblastic disease
Molar pregnancies
Invasive hydatidiform mole
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PubMed Search: Invasive hydatidiform mole
Table of Contents
Definition / general | Essential features | Terminology | ICD coding | Epidemiology | Sites | Pathophysiology | Etiology | Clinical features | Diagnosis | Laboratory | Radiology description | Radiology images | Case reports | Treatment | Gross description | Gross images | Microscopic (histologic) description | Microscopic (histologic) images | Virtual slides | Positive stains | Negative stains | Sample pathology report | Differential diagnosis | Additional references | Board review style question #1 | Board review style answer #1 | Board review style question #2 | Board review style answer #2Cite this page: Sheikh FN, Gupta R, Lanjewar S. Invasive hydatidiform mole. PathologyOutlines.com website. https://www.pathologyoutlines.com/topic/placentainvasivemole.html. Accessed April 19th, 2024.
Definition / general
- Invasive hydatidiform mole is a hydatidiform mole that has invaded the myometrium / uterine vessels or is present in extrauterine sites (metastatic hydatidiform mole)
Essential features
- Most common form of persistent gestational trophoblastic disease after persistent hydatidiform mole
- Defined as molar gestation invading the uterine wall, vessels or extrauterine sites
- Extrauterine sites include vaginal / pelvic wall, lungs, vulva
- Most commonly results from complete hydatidiform mole, presenting with persistently elevated human chorionic gonadotropin (hCG) after primary molar evacuation
- Rarely diagnosed on imaging prior to evacuation
- Chemotherapy is highly effective with a cure rate of > 80% (Int J Gynecol Pathol 2016;35:134)
Terminology
- Invasive mole
ICD coding
- ICD-O: 9100/1 - invasive hydatidiform mole
Epidemiology
- After persistent hydatidiform mole, invasive / metastatic hydatidiform mole is the most common form of persistent gestational trophoblastic disease
- Incidence of invasive / metastatic hydatidiform mole is 6 - 10 times higher than choriocarcinoma
- Reference: Kurman: Blaustein Pathology of the Female Genital Tract, 7th Edition, 2019
Sites
- Uterus
- Extrauterine sites: vaginal wall / pelvis (most common), vulva, lungs (Kurman: Blaustein Pathology of the Female Genital Tract, 7th Edition, 2019)
Pathophysiology
- Unknown at this time
Etiology
- Most commonly develops from complete hydatidiform moles (Int J Gynecol Pathol 2016;35:134)
- Rarely seen after a partial mole (Curr Oncol Rep 2014;16:408)
Clinical features
- Vaginal bleeding with persistent serum human chorionic gonadotropin (hCG) after evacuation of a hydatidiform mole is the characteristic presentation (Rev Bras Ginecol Obstet 2015;37:42)
Diagnosis
- Pelvic imaging but can rarely be diagnosed before evacuation
- Uterine evacuation / resection
Laboratory
- Persistently high hCG levels after evacuation of a hydatidiform mole
Radiology description
- It is difficult to differentiate an invasive mole from other forms of gestational trophoblastic disease on imaging
- Pelvic ultrasound
- Echogenic vascular mass invading the myometrium
- High velocity and low impedance flow on color Doppler interrogation
- Pelvic magnetic resonance imaging (MRI)
- Often appears as a poorly defined mass that deeply invades the myometrium
- Complete or partial disruption of the junctional zone may also be seen
- Reference: Radiopaedia: Invasive Mole [Accessed 12 May 2023]
Radiology images
Images hosted on other servers:
Ill defined lesion with solid and cystic areas
Case reports
- 31 year old woman presented with abdominal pain and scanty vaginal bleeding 53 days postabortion (Front Surg 2022;8:798640)
- 36 year old primigravida woman presented with vaginal bleeding and hCG elevation after removal of a complete hydatidiform mole (Am J Case Rep 2021;22:e931156)
- 41 year old woman who had been pregnant 3 times, had 2 deliveries after 24 weeks gestation and had 1 abortion (G3P2Ab1) presented 2 months after curettage of molar pregnancy with vaginal bleeding and acute abdomen (J Reprod Infertil 2017;18:205)
Treatment
- Chemotherapy has a cure rate of > 80% (Int J Gynecol Pathol 2016;35:134)
Gross description
- Erosive and hemorrhagic lesion
- Superficial or complete invasion of the myometrium that can perforate the uterus and involve periuterine structures
- Hydropic villi may be seen
- Reference: Kurman: Blaustein Pathology of the Female Genital Tract, 7th Edition, 2019
Gross images
Images hosted on other servers:
Hydatidiform mole invading the cervix
Microscopic (histologic) description
- Presence of molar villi with associated trophoblasts in the myometrium, uterine vessels or extrauterine sites is a diagnostic feature
- Typically, the morphologic characteristics of complete (most common) or partial mole are seen in the invasive component; villi are usually less hydropic but can also show prominent hydropic changes with increased trophoblast hyperplasia
- Metastatic hydatidiform moles are most commonly complete hydatidiform moles in extrauterine locations
- Reference: Kurman: Blaustein Pathology of the Female Genital Tract, 7th Edition, 2019
Microscopic (histologic) images
Contributed by Sonali Lanjewar, M.D., M.B.B.S.
Villi invading myometrium
Trophoblastic proliferation
Virtual slides
Images hosted on other servers:
Invasive hydatidiform mole
Positive stains
- Intact nuclear p57 expression in the villous cytotrophoblast and villous stromal cells in invasive hydatidiform moles associated with partial moles
Negative stains
- Loss of nuclear p57 expression in the villous cytotrophoblast and villous stromal cells in invasive complete hydatidiform mole
Sample pathology report
- Uterus, hysterectomy:
- Invasive hydatidiform mole (see comment)
- Comment: Chorionic villi are seen invading the myometrium.
Differential diagnosis
- Choriocarcinoma:
- Also presents with high hCG
- Has more striking cytologic atypia and proliferation in addition to a biphasic pattern of atypical syncytiotrophoblasts and cytotrophoblasts
- Lacks villi (except in the rare instance of gestational choriocarcinoma)
- Placenta accreta:
- Normal placenta with villous implants invading into the myometrium without an intervening decidual layer
- Villi do not show hydropic changes and lack trophoblastic hyperplasia and atypia
- Seen in term placenta whereas molar pregnancies are characteristically seen in first trimester
Additional references
Board review style question #1
What is the most common site for metastatic invasive hydatidiform mole?
- Lungs
- Pelvis / vaginal wall
- Peritoneal cavity
- Vulva
Board review style answer #1
B. Pelvis / vaginal wall. The pelvis / vaginal wall is the most common site for metastatic hydatidiform moles. Answers D and A are incorrect because vulva and lungs are the next most common sites. Answer C is incorrect because metastatic invasive hydatidiform moles are not usually seen in the peritoneal cavity.
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Reference: Invasive hydatidiform mole
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Reference: Invasive hydatidiform mole
Board review style question #2
Which of the following is true about invasive hydatidiform mole?
- Grossly presents as a mass-like lesion
- It is a rare type of persistent gestational trophoblastic disease
- Presents as a persistent elevation of hCG after primary evacuation of a hydatidiform mole
- They can usually be diagnosed by imaging prior to removal
Board review style answer #2
C. Presents as a persistent elevation of hCG after primary evacuation of a hydatidiform mole. In invasive / metastatic hydatidiform moles, hCG levels are persistently high despite the evacuation of the primary molar pregnancy. Answer A is incorrect because invasive hydatidiform moles present as an erosive, hemorrhagic lesion on gross examination. Answer B is incorrect because invasive hydatidiform moles are second only to primary hydatidiform moles in incidence. Answer D is incorrect because in most cases, imaging is not helpful in its diagnosis.
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Reference: Invasive hydatidiform mole
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Reference: Invasive hydatidiform mole
