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Placental chorioangioma

A placental chorioangioma is a benign vascular tumour of placental origin. It is the most common tumour of the placenta, and is usually found incidentally.

Epidemiology

The estimated incidence is at ~1% 3 of all pregnancies.

Clinical presentation

In most cases chorioangiomas are asymptomatic, and merely incidental findings. Occasionally, when they are large or multiple, they can result in poor outcomes for both the fetus and the mother.

Pathology

Chorioangiomas 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 give a fetal thrombocytopenia

There is some debate as to the exact nature of chorioangiomas. Most authors consider them as a benign neoplasm while others however, categorise them as hamartomas, given their composition of mostly native placental tissue and their inability to metastasise.

There can be significant variation in size. Most lesions tend to small and lesions > 4 cm are generally rare 8. Large tumours can however produce degenerative phenomenona like, necrosis, calcification, hyalinization, or myxomatous degeneration.

Sub types

Three histological types are recognised:

  • angiomatoid- adult: characterised by numerous blood vessels
  • cellular-young: with poor vascularisation
  • degenerative :
Genetics

Most cases tend to be sporadic.

Location

They tend to occur on the fetal side of the placenta (close to cord insertion).

Associations
Markers

Radiographic features

Ultrasound

Typically a chorioangioma is located near the insertion of the cord, and protrudes into the amniotic cavity.

  • often seen as a hypo-echoic, 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

Colour Doppler interrogation often demonstrates 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 6.

Fetal MRI

MRI usually demonstrates a heterogeneous mass. Signal characteristics include: 

  • T1:  iso-intense to placenta if uncomplicated can be hyperintense if there has been a haemorrhage
  • T2: high signal intensity (can be hheterogeneous, an appearance similar to that of a haemangioma 6.

Complications

Vascular shunting may cause fetal high-output cardiac failure and hydrops fetalis.

Other complications include:

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 12.

The overall prognosis is somewhat dependent on the presence and / or development of hydrops fetalis. In general lesions, larger than 4 cms are considered to produce haemodynamic effects on the fetus 3. Therapeutic amnio-drainage is an option if there is excessive polyhydramios. 

History and etymology

They were thought ot have been first described by Clarke in 1798 13 .

Differential diagnosis

For ultrasound appearances consider:

See also

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