Prenatal sonographic features of fetal mediastinal teratoma

Mature Triphyllic Cystic Teratoma of the Posterior Mediastinum in a Fetus: A Case Report and Literature Review

A teratoma is a neoplasm composed of cell populations or tissues that are reminiscent, in their appearance, of normal elements derived from at least two embryonic layers. Fetal mature teratomas are normally benign, cystic, and typically occur along the midline, while they are rare in the posterior mediastinum. Teratomas are frequently solitary; however, they may sometimes be associated with other congenital anomalies and/or with chromosomal abnormalities. Clinically, they are often asymptomatic but can occasionally cause compression symptoms. Prenatal diagnoses are uncommon and made with ultrasonography; differential diagnosis with other congenital conditions is mandatory. We report the case of a 21 weeks of gestational age old fetus with a mature triphyllic fetal cystic teratoma, grade 0, located in the right posterior mediastinum. The tumor presented as a 3 cm wide cystic mass that caused a contralateral shift of the surrounding structures. Histological examination later revealed the presence of derivatives of the three germ layers, such as hyaline cartilage, smooth muscle, nervous tissue, and a respiratory-type epithelium.

Prenatal Diagnosis of Fetal Heart Failure

Fetal heart failure (FHF) is a condition of inability of the fetal heart to deliver adequate blood flow for tissue perfusion in various organs, especially the brain, heart, liver and kidneys. FHF is associated with inadequate cardiac output, which is commonly encountered as the final outcome of several disorders and may lead to intrauterine fetal death or severe morbidity. Fetal echocardiography plays an important role in diagnosis of FHF as well as of the underlying causes. The main findings supporting the diagnosis of FHF include various signs of cardiac dysfunction, such as cardiomegaly, poor contractility, low cardiac output, increased central venous pressures, hydropic signs, and the findings of specific underlying disorders. This review will present a summary of the pathophysiology of fetal cardiac failure and practical points in fetal echocardiography for diagnosis of FHF, focusing on essential diagnostic techniques used in daily practice for evaluation of fetal cardiac function, such as myocardial performance index, arterial and systemic venous Doppler waveforms, shortening fraction, and cardiovascular profile score (CVPs), a combination of five echocardiographic markers indicative of fetal cardiovascular health. The common causes of FHF are reviewed and updated in detail, including fetal dysrhythmia, fetal anemia (e.g., alpha-thalassemia, parvovirus B19 infection, and twin anemia-polycythemia sequence), non-anemic volume load (e.g., twin-to-twin transfusion, arteriovenous malformations, and sacrococcygeal teratoma, etc.), increased afterload (intrauterine growth restriction and outflow tract obstruction, such as critical aortic stenosis), intrinsic myocardial disease (cardiomyopathies), congenital heart defects (Ebstein anomaly, hypoplastic heart, pulmonary stenosis with intact interventricular septum, etc.) and external cardiac compression. Understanding the pathophysiology and clinical courses of various etiologies of FHF can help physicians make prenatal diagnoses and serve as a guide for counseling, surveillance and management.

Fetal thoracic teratomas: mediastinal or pericardial?

BACKGROUND

Mediastinal and pericardial teratomas have overlapping imaging features that may make accurate prenatal diagnosis challenging.

OBJECTIVE

To identify prenatal imaging features that may aid in distinguishing between mediastinal and pericardial teratomas.

MATERIALS AND METHODS

Prenatally diagnosed pericardial and mediastinal teratomas evaluated at our fetal center from 1995 to 2020 were included in this Institutional Review Board-approved study. Lesion volume was calculated using prospectively reported ultrasound (US) measurements and the formula of a prolate ellipsoid, which was then normalized to head circumference. Prenatal US and magnetic resonance imaging (MRI) studies were anonymized with two fetal imagers reviewing the US studies and two different fetal imagers reviewing the MRI studies. These experienced reviewers scored location of the mass in the craniocaudal axis and in the transverse axis. MRI reviewers also scored the presence of inferior cardiac compression by the lesion and whether there was identifiable thymic tissue. Reviewer disagreements were resolved by consensus review.

RESULTS

Eleven pericardial teratomas and 10 mediastinal teratomas were identified. All cases underwent detailed fetal anatomic US and fetal echocardiogram and 10/11 (91%) pericardial teratomas and 8/10 (80%) mediastinal teratomas underwent fetal MRI. Median volume was higher for mediastinal teratomas compared to pericardial teratomas (42.5 mL [interquartile range (IQR) 15.9 - 67.2 mL] vs. 8.1 mL [IQR 7.7 - 27.7 mL], P=0.01) and median volume/head circumference was also statistically higher in mediastinal teratomas (1.33 [IQR 0.78 - 2.61] vs. 0.43 [IQR 0.38 - 1.10], P=0.01). Logistic regression analysis demonstrated a statistical difference between teratoma types with respect to location in the craniocaudal axis by both modalities with mediastinal teratomas more commonly located in the upper and upper-middle thorax compared to pericardial teratomas, which were more commonly found in the middle thorax (US, P=0.03; MRI, P=0.04). Logistic regression analysis also demonstrated a statistical difference between teratoma types with respect to position along the transverse axis by both modalities with mediastinal teratomas more commonly located midline or left paramedian and pericardial teratomas more often right paramedian in location (US, P<0.01; MRI, P=0.02). Inferior cardiac compression observed by MRI was associated more commonly with mediastinal teratomas compared to pericardial teratomas (87.5% [7/8] vs. 10% [1/10], P<0.01). Identifiable thymus by MRI was more commonly observed in cases of pericardial teratomas, however, this difference was not statistically significant (P=0.32).

CONCLUSION

Mediastinal teratomas are associated with larger lesion size and inferior cardiac compression when compared to pericardial teratomas. These features combined with lesion location in the craniocaudal and transverse axes may allow for more accurate prenatal diagnosis and optimal perinatal and surgical management.

Prenatal ultrasonic features of a mediastinal teratoma: A case report and literature review

Fetal mediastinal teratomas represent only 10% of congenital teratomas in children and 2.6% of all mediastinal masses in children. Teratomas have multifactorial etiology, such as chromosomal abnormalities. Fetal mediastinal teratomas are rare. Mediastinal teratomas can cause hydrops fetalis, fetal demise, and neonatal respiratory distress; therefore, accurate perinatal management and interventions are very important. We describe a case of fetal mediastinal teratoma wherein the cystic fluid in the fetal tumor was aspirated and confirmed by surgical pathology after birth at the authors' center. The teratoma in this case was characterized by a large single cystic mass with clear borders in the anterosuperior mediastinum, which grew rapidly and was closely related to the thymus. The infant was healthy at birth, and the tumor was surgically removed the age of 1 year. The postoperative course was uneventful, and the patient was in good health 6 years postoperatively. This case and literature review suggests that ultrasound examination can accurately diagnose fetal mediastinal teratomas, which is beneficial to provide an accurate basis for fetal prenatal intervention and treatment. Additionally, an important ultrasound feature of a fetal unicystic mediastinal teratoma is a saddle-shaped mass with clear boundaries, which provided an accurate reference for the diagnosis of a fetal cystic mediastinal teratoma by prenatal ultrasonography.

[Fetal mediastinal teratomas. Report of two cases]

Teratomas are one of the most common tumors diagnosed in fetuses and newborns. In this age group, extragonadal teratomas predominate, among which the mediastinum ones accounts for up to 15% of teratomas of the perinatal period. They may be associated with the thymus or thyroid gland; in some cases a clear connection with adjacent organs cannot be identified. Teratomas of the heart, also localized in the mediastinum, are often considered separately from the mediastinal ones; most often the tumor affects the pericardium. The article describes two cases of mediastinal teratomas detected by ultrasound in the second trimester of pregnancy, with signs of rapid growth and compression symptoms typical for this localization of the tumor - hydropericardium and other manifestations of non-immune fetal hydrops. In both cases, immature teratomas (grade 2 and 3) were diagnosed with a predominance of immature neuroectodermal tissue, as well as with the presence of endoderm derivatives, including areas of the hepatoid structure, microglandular structures and cysts lined with mucus-forming epithelium. The mesodermal component was represented by hyaline cartilage. An immunohistochemical study revealed an extremely high proliferative activity in the immature neuroectodermal component - more than 90% of positive nuclei were detected in the neuroepithelium upon reaction with Ki67 antibodies. In all other tissue elements, proliferative activity was low.

Fetal Presentation of Mediastinal Immature Teratoma: Ultrasound, Autopsy and Cytogenetic Findings

Teratomas are the most common congenital tumors, occurring along the midline or paraxial sites, or uncommonly, the mediastinum. Teratomas are classified as mature, containing only differentiated tissues from the three germinal layers; and immature, which also present with neuroectodermal elements, ependymal rosettes, and immature mesenchyme. Herein, we describe a new case of fetal mediastinal immature teratoma detected at 21 weeks of gestational age (wga) + 1 day with thorough cytogenetic analysis. Ultrasound (US) showed a solid and cystic mass located in the anterior mediastinum, measuring 1.8 × 1.3 cm with no signs of hydrops. At 22 wga, US showed a mass of 2.4 cm in diameter and moderate pericardial effusions. Although the prenatal risks and available therapeutic strategies were explained to the parents, they opted for termination of pregnancy. Histology showed an immature teratoma, Norris grade 2. Karyotype on the fetus and tumor exhibited a chromosomal asset of 46,XX. The fetal outcome in the case of mediastinal teratoma relies on the development of hydrops due to mass compression of vessels and heart failure. Prenatal US diagnosis and close fetal monitoring are paramount in planning adequate treatment, such as in utero surgery, ex utero intrapartum therapy (EXIT) procedure, and surgical excision after birth.