Placental chorioangioma

Last revised by Joshua Yap on 4 May 2023

Placental chorioangiomas are benign vascular tumors of placental origin. It is the most common tumor of the placenta and is usually found incidentally.

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

Recognized associations include:

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.

A chorioangioma is thought to arise as a malformation of the primitive angioblastic tissue of the placenta. The angiomas are perfused by fetal circulation and thus, when they are large, they may represent a significant impediment to fetal cardiac activity. They may also sequester platelets and can, in turn, give fetal thrombocytopenia

There is some debate as to the exact nature of chorioangiomas. Most authors consider them as benign neoplasms, while others categorize them as hamartomas, given their composition of mostly native placental tissue and their inability to metastasize.

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

Three histological types are recognized:

  • angiomatoid: characterized by numerous blood vessels

  • cellular: with poor vascularization

  • degenerative

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

Most cases tend to be sporadic.

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

  • usually contains anechoic "cystic" areas and can be seen as distinctly separate from normal surrounding placental tissue

  • some heterogeneous areas caused by degenerative processes and internal hemorrhage can be seen

  • can also rarely appear pedunculated

  • on color Doppler, often demonstrates low resistance pulsatile flow within the anechoic "cystic" areas, which represent enlarged vascular channels

Large chorioangiomas may undergo spontaneous infarction with decreased echogenicity, decreased tumor volume, and decreased blood flow on color Doppler images 6.

MRI usually demonstrates a heterogeneous mass.

  • T1: isointense to placenta if uncomplicated can be hyperintense if there has been a hemorrhage

  • T2: high signal intensity; can be heterogeneous, an appearance similar to that of a hemangioma 6

Chorioangiomas are usually treated with expectant management, as the majority of tumors are asymptomatic. Small tumors are often monitored with ultrasound around every 6-8 weeks, whereas large tumors require serial ultrasound examinations more frequently around every 1-2 weeks. Some tumors may even regress spontaneously during pregnancy 12.

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

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

Other complications include:

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

For ultrasound appearances consider:

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Cases and figures

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