placental chorioangioma

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

Epidemiology

The estimated incidence is at ~1% 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

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 a benign neoplasm while others, however, 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 small and lesions >4 cm are rare . Large tumors can, however, produce degenerative phenomena like necrosis, calcification, hyalinisation, or myxomatous degeneration.

Subtypes

Three histological types are recognized:

• angiomatoid: characterized by numerous blood vessels
• cellular: with poor vascularization
• 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

Recognized associations include:

• hydrops fetalis: also listed under complications
• polyhydramnios: also listed under complications
• Beckwith-Wiedemann syndrome
• single umbilical artery
• fetal anemia
• fetal congestive cardiac failure
• hepatic and cutaneous hemangiomas
• IUGR

Markers

• raised maternal alpha-fetoprotein (MSAFP)

Radiographic features

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 and internal hemorrhage can be seen
• chorioangiomas can also rarely appear pedunculated
• 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 .

MRI

MRI usually demonstrates a heterogeneous mass. Signal characteristics include:

• 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

Treatment and prognosis

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

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 . Therapeutic amnio-drainage is an option if there is excessive polyhydramnios.

Complications

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

Other complications include:

• polyhydramnios
• premature labor
• fetal thrombocytopenia
• intrauterine growth restriction (IUGR)
• placental abruption
• pre-eclampsia

History and etymology

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

Differential diagnosis

For ultrasound appearances consider:

• subamniotic hematoma
• partial hydatidiform mole
• submucosal uterine fibroid: sub-mucosal leiomyoma of the uterus
• placental teratoma
• atypical placental venous lake: on greyscale imaging

See also

• placental chorioangiomatosis: with multiple chorioangiomas
• placental tumors

Siehe auch:

• Leiomyofibrom Uterus
• Blasenmole
• placental venous lakes
• placental chorioangiomatosis
• placental teratoma
• mesenchymale Dysplasie der Plazenta
• Tumoren der Plazenta
• sub-amniotic haematoma

und weiter:

• obstetric curriculum
• Chorion
• altered alpha fetoprotein levels
• fetal cardiomegaly
• fetal anaemia
• fetal thrombocytopaenia
• benign vascular tumours