Placental Chorioangioma: A Rare and Often Overlooked Cause of Polyhydramnios
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INTRODUCTION
Placental tumors are broadly classified into trophoblastic and non-trophoblastic types. Placental chorioangioma is the most common benign neoplasm in nontrophoblastic tumors. However, placental chorioangioma remains a rare condition in absolute terms, with an estimated incidence of only 0.16%–1% of all pregnancies (Fan & Skupski, 2014; Wou et al., 2011). Although the prognosis is generally favorable, large chorioangiomas can disrupt the placental blood flow and lead to adverse maternal and fetal outcomes, including polyhydramnios, fetal hydrops, hemodynamic changes, preterm birth, and even fetal demise. This editorial briefly highlighted placental chorioangioma as a frequently overlooked, yet clinically relevant condition, emphasizing on its potentially manageable perinatal complications.
OVERVIEW AND CLINICAL CHARACTERISTICS
Chorioangioma is a benign vascular placental tumor, and is classified as a type of placental hemangioma (Fig. 1). Although the pathophysiology and molecular mechanisms of chorioangioma remain poorly understood, recurrent cases reported in pregnant women with Fontan circulation and in those residing at high altitudes is suggestive of hypoxia-driven angiogenesis mediated by overexpression of angiogenic cytokines (Fan & Skupski, 2014). Maternal hypertension, diabetes, and female fetuses have been more frequently associated with chorioangiomas; however, data on genetic factors remain limited (Guschmann et al., 2003).
Gross appearance of a placental chorioangioma. (A) Gross examination revealed an irregularly shaped, white-grey, rubbery, solid mass measuring 4 cm×3.5 cm×1.5 cm and weighing 25 g within the placental tissue. (B) Cut surface appearance of the mass. Sectioning of the chorioangioma showed a whitish and gelatinous cut surface. Histopathological examination confirmed the diagnosis of chorioangioma.
Most chorioangiomas are small, asymptomatic, and often undetectable on routine prenatal ultrasonography. However, these occasionally grow into large masses, exceeding 15 cm in diameter (Kesrouani et al., 2013). Tumors measuring greater than 4–5 cm in diameter are classified as large chorioangiomas and are more likely to be detected. Nevertheless, these occur in approximately 1 in 10,000 pregnancies and can be overlooked or diagnostically challenging (Guschmann et al., 2003).
PERINATAL COMPLICATIONS AND PROGNOSTIC FACTORS
Larger (>4 cm) or multiple tumor lesions are associated with increased risks of adverse perinatal outcomes, primarily due to hemodynamic disturbances from abnormal arteriovenous shunting within the tumor (Buca et al., 2020; Wu et al., 2025). As the tumor enlarges, it may function as an arte riovenous shunt leading to high-output cardiac failure in the fetus. This can result in nonimmune hydrops fetalis, cardio megaly, polyhydramnios, increased midcerebral artery velocity, and congestive heart failure (Fan & Skupski, 2014). Consistent with these pathophysiologic mechanisms, a large 10-year study including 175 cases of placental chorioangioma reported that approximately one-third of pregnancies complicated by large tumors (≥4 cm) were associated with severe maternal and fetal complications and required prenatal intervention, and about 20% of affected fetuses or neonates resulted in prenatal death (Ma et al., 2023).
Polyhydramnios is a common complication associated with large placental chorioangiomas. In a subset of this cohort that analyzed 44 cases with tumors measuring ≥4 cm, approximately 27% of pregnancies were complicated by polyhydramnios, often with rapid onset in the second or third trimester. This may lead to maternal respiratory discomfort, preterm labor, and premature rupture of membranes (Dong et al., 2020). However, because polyhydramnios is often idiopathic or attributed to fetal structural anomalies, rare placental causes such as chorioangioma may be overlooked.
Although chorioangiomas can affect fetoplacental circulation (thrombocytopenia and consumptive coagulopathy due to platelet sequestration) and cause multiple complications, these are not clearly associated with structural congenital anomalies. Nevertheless, rare reports of large chorioangiomas coexisting with cranial malformations or choanal atresia suggest a possible secondary effect of chronic hypoxia or altered hemodynamics during organogenesis (Dong et al., 2020).
The severity of complications is positively correlated with tumor size, underscoring the importance of serial monitoring of absolute dimensions and growth rates over time. One study reported that the incidence of hydrops fetalis increased progressively with tumor size ranging from 15% to 52% for chorioangiomas measuring 2–10 cm (in 2 cm increments) (Buca et al., 2020). However, even in the absence of ultrasonographic abnormalities, chorioangiomas <2 cm are associated with an increased risk of neonatal morbidity, as indicated by higher neonatal intensive care unit admission rates (Wou et al., 2011).
DIAGNOSTIC CHALLENGES AND CLINICAL IMPLICATIONS OF PLACENTAL CHORIOANGIOMA
Placental chorioangiomas are typically detected incidentally during prenatal ultrasonography and appear on gray-scale ultrasound as well-circumscribed hypoechoic or hyperechoic masses that are distinct from the surrounding placental tissue. In larger lesions, color Doppler aids in detecting feeding vessels, and distinguishing chorioangiomas from other placental masses. Tumor vascularity is correlated with prognosis, with low-vascularity tumors generally linked to better outcomes. When ultrasonographic findings are inconclusive, the use of fetal magnetic resonance imaging (MRI) using fast low-angle shot and half-Fourier acquisition single-shot turbo spin-echo sequences have been used as an adjunct modality to demonstrate heterogeneous masses on the fetal side of the placenta with signal intensities higher than normal placental parenchyma on both T1- and T2-weighted images (Fig. 2) (Fan & Skupski, 2014).
Axial T2-weighted HASTE image shows about a 3.1-×3.2-×3.4-cm round, well-circumscribed solid mass with homogeneous intermediate signal intensity (white solid arrow) in the placenta (asterisk), adjacent to the cord insertion site (white dashed arrow), at a gestational age of 28 weeks. HASTE, half-Fourier acquisition single-shot turbo spin-echo.
An important limitation for placental chorioangioma diagnosis is not an inadequacy of the imaging techniques but is the frequent omission of placental evaluation. Despite the use of targeted serial ultrasonography and fetal MRI to investigate polyhydramnios or other complicated fetal abnormalities, placental lesions are often overlooked and remain undetected. Clinical assessments tend to prioritize fetal structural anomalies as the primary causes of polyhydramnios due to which rare antenatal placental conditions such as chorioangioma might be overlooked. Consistent with this observation, only 29% of chorioangiomas ≥2 cm were identified prenatally on ultrasound in a previous study (Wou et al., 2011). However, accumulating evidence suggests that prenatal detection, particularly of large chorioangiomas, has improved with advances in ultrasonographic resolution and routine use of color Doppler imaging. In a recent single-center series of 30 histologically confirmed cases, all 3 large lesions (5.5–12 cm) were identified antenatally and then using serial ultrasonography (Nardi et al., 2024). Similarly, a large retrospective study proposed a tumor diameter threshold of 4.7 cm for risk stratification and recommended close sonographic surveillance at 1–2 weeks intervals, including assessment of amniotic fluid volume and fetal Doppler parameters for lesions exceeding this size (Wu et al., 2025).
Prenatal detection of chorioangioma is clinically relevant, particularly in pregnancies complicated by polyhydramnios. This is because a timely diagnosis may facilitate individualized monitoring and management including close surveillance for complications such as mirror syndrome, preterm labor, and fetal hemodynamic compromises. Conservative interventions, such as serial amnioreduction or symptomatic treatment, can be employed, and in selected cases, early interventional approaches including fetoscopic laser coagulation or vascular embolization can be considered to interrupt tumor blood flow and improve outcomes (Agarwal et al., 2023).
CONCLUSION
Chorioangiomas are not always identified during routine prenatal sonographic screening, particularly when clinical attention is primarily directed toward fetal abnormalities. This brief review highlights the importance of incorporating detailed placental evaluation into the diagnostic workup for unexplained fetal compromise especially in cases accompanied by polyhydramnios, to reduce the risk of missed or delayed diagnosis and allow timely intervention. Therefore, careful evaluation of the placenta should be considered when abnormalities in the amniotic fluid volume or maternal-to-fetal hemodynamic changes are observed on ultrasonography, even though chorioangiomas are uncommon.
CONFLICT OF INTEREST
The authors have nothing to disclose.