Placental Chorioangioma is a benign vascular tumor, originating from the placenta.It is the most common tumour of the placenta, and is usually found incidentally.
Epidemiology:
The estimated incidence is at ~1% of all pregnancies
Pathogenesis:
They were thought to have been first described by Clarke in 1798. A chorioangioma is generally thought to arise as a malformation of the primitive angioblastic tissue of the placenta. The angiomas are perfused by the fetal circulation and thus, when they are large, may represent a significant impediment to fetal cardiac activity. They may also sequester platelets and can in turn result to fetal thrombocytopenia.
There is some debate as to the exact nature of chorioangiomas. Most authors consider them as a benign neoplasm while others, categorise them as hamartomas, given their composition of mostly native placental tissue and their inability to metastasise.
Chorioangiomas vary greatly in size. Most chorioangiomas tend to be small and lesions >4 cm are generally rare. Large tumours can however produce degenerative phenomenona like, necrosis, calcification, hyalinisation, or myxomatous degeneration.
Subtypes:
Three histological types are recognised
> Angiomatoid: Characterised by numerous blood vessels
> Cellular: with poor vascularisation
> Degenerative
Location: They tend to occur on the fetal side of the placenta (close to cord insertion).
Associations:
The following are the recognized association of Placental Chorionagioma
- Beckwith-Wiedemann Syndrome
- Single Umbilical Artery
- Fetal Anaemia
- Fetal Congestive Heart Failure
- Hydrops Fetalis
- Polyhydramnios
Markers
- Raised Maternal Alpha Feto-Protein
Diagnosis:
Ultrasound:
Typically a chorioangioma is located near the insertion of the cord, and protrudes into the amniotic cavity.
>Often seen as a hypoechoic, rounded mass, located near the chorionic plate +/- umbilical cord insertion site.
>It usually contains anechoic 'cystic' areas, and can be seen as distinctly separate to normal surrounding placental tissue
>Some heterogeneous areas caused by degenerative processes/ internal haemorrhage can be seen.
>Chorioangiomas can also rarely appear pedunculated
>Doppler: often demonstrates low resistance pulsatile flow within the anechoic 'cystic' areas, which actually represent enlarged vascular channels.
Large chorioangiomas may undergo spontaneous infarction with decreased echogenicity, decreased tumour volume, and decreased blood flow on colour Doppler images.
Fetal MRI
MRI usually demonstrates a heterogeneous mass. Signal characteristics include:
>T1: isointense to placenta if uncomplicated can be hyperintense if there has been a haemorrhage
>T2: high signal intensity; can be heterogeneous, an appearance similar to that of a haemangioma
Complications
Vascular shunting may cause fetal high-output cardiac failure and hydrops fetalis.
Other complications include:
- Polyhydramnios
- Premature Labour
- Fdetal Thrombocytopaenia
- Intra-uterine Growth Restriction (IUGR)
- Placental Abruption
- Pre-Eclampsia
Treatment and Prognosis:
Chorioangiomas are usually treated with expectant management, as the majority of tumours are asymptomatic. Small tumours are often monitored with ultrasound ~every 6-8 weeks, whereas large tumours require serial ultrasound examinations more frequently ~every 1-2 weeks. Some tumours may even regress spontaneously during pregnancy.
The overall prognosis is somewhat dependent on the presence and/or development of hydrops fetalis. Chorioangioma larger than 4 cm are considered to produce haemodynamic effects on the fetus. Therapeutic amnio-drainage is an option if there is excessive polyhydramios.
Differential Diagnosis:
Ultrasound Differntial Diagnosis includes:
> Sub-amniotic Hematoma
> Partial hydatidiform mole
> Placental Teratoma
> Atypical Venous lake
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