Prenatal diagnosis of fetal umbilical cord teratoma

Introduction

Congenital umbilical cord teratomas are extremely rare tumors of the umbilical cord [2]. As teratomas include tissues from all three germ-cell layers, they have both cystic and solid components that can be defined prenatally by ultrasonography. There were 14 teratoma cases reported in the English literature and four of these cases have the diagnosis of both exomphalos and teratoma [3, 4, 7, 8, 12]. Other malformations and chromosomal aberrations were also defined as being associated with umbilical cord teratomas [4, 7, 8, 12]. As teratomas can lead to adverse fetal outcomes, close follow up of the fetus is recommended [3, 4, 7, 8, 12]. Here we report an umbilical cord teratoma without any associated abnormalities, diagnosed prenatally which lead to fetal demise in utero.

Case

A 32-year-old pregnant woman gravida 3, para 2, was referred to our clinic with a diagnosis of omphalocele at 15 weeks of gestation. Her previous pregnancies were uneventful. The results of her integrated prenatal screening tests for this pregnancy were negative.

In the evaluation of the fetus, ultrasonography (USG) (Aplio 80, Toshiba, Tokyo, Japan) revealed a mass (25×22×24 mm in diameter) that was located next to the fetal abdomen containing a heterogeneous area, both echogenic and hypoechogenic, suggesting solid and cystic structures (Figure 1A and B). The hyperechogenic area was thought to be the bowel, thus the lesion was first defined as a hypogastric omphalocele. An acardiac twin and tumor of the umbilical cord were the other options considered in the differential diagnosis.

Figure 1

(A) A 22.7 mm lesion near the fetal abdomen, seen by ultrasonography at the 16th week of gestation. The arrow shows the mass with both hyper- and hypoechoic areas. (B) Ultrasonographic appearance that shows the relation between the mass, fetal abdomen and umbilical cord. Arrow indicates the umbilical vessels.

An amniocentesis was performed to exclude chromosomal abnormalities, which showed normal 46,XX karyotype. The mass was further investigated at 18 weeks by USG and at 21 weeks by USG and magnetic resonance imaging (MRI) (3T, Achieva, Philips, Nijmegen, The Netherlands) using a torso phased-array coil with the mother in the supine position to rule out the other differential diagnoses such as acardiac twin and tumors of the umbilical cord. MRI sequences performed were single-shot turbo spin-echo and T1-weighted in the axial, coronal and sagittal planes with respect to the fetus, a field-of-view of 400 mm or less when possible, and a slice thickness of 3 mm (Figure 2). Doppler findings of the umbilical artery were within normal limits in all examinations. The single-shot turbo spin-echo and T1-weighted images demonstrated a 36×49×52 mm heterogeneous mass, related with the umbilical cord. The lesion had both cystic and solid patterns. All small and large bowel loops, fetal liver, gallbladder, stomach, spleen, bilateral kidneys and bladder of the fetus were demonstrated in normal localizations. As the tumor had a heterogeneous character containing umbilical vascular structures (two arteries and one vein) (Figure 2) it was identified as teratoma of the umbilical cord.

Figure 2

Single-shot turbo spin-echo images of the umbilical cord mass (star indicates the teratoma; black arrow indicates umbilical vessels – two arteries and one vein; white arrow indicates the cord insertion to abdominal wall).

In the next antenatal visit at 26 weeks, fetal cardiac activity was absent. A female fetus weighing 748 g was delivered vaginally. On macroscopic examination, a mass measuring 60×55×45 mm and 25 mm away from the fetal umbilicus in the umbilical pouch was visualized (Figure 3). The tumor tissue was gray-to-yellow colored, containing osseous-like areas. The microscopic examination of the mass revealed tissues derived from the endodermal, mesodermal and neuroectodermal germ layers (Figure 4A–D). There were glandular structures lined with columnar epithelium beside highly differentiated glial and fat tissue. In addition to this, stratified squamous epithelium, sebaceous gland, cartilage and bone tissue were defined. There was no malignant differentiation. In respect to these findings, the tumor was diagnosed as teratoma of the umbilical cord. The cord length was 100 mm, containing three vessels, and it had a paracentral placental insertion. In the microscopic examination of the umbilical vein, the lumen proximal to teratoma was nearly three-quarters of the diameter compared to distal portion. Post-mortem examination of the female fetus did not reveal any further malformation and all organs had the usual anatomic localization with normal development.

Figure 3

Macroscopic appearance of the teratoma and fetus.

Figure 4

Microscopic evaluation of umbilical cord teratoma. (A) Squamous epithelial islands involving keratinous material centrally. These islands are located in between the mesenchymal elements of fat and connective tissue. (B) Area of bone tissue in the teratoma. (C) Area of glandular tissue lined by the columnar epithelium. (D) Area of glial tissue.

Discussion

Teratomas are the most frequent congenital tumors and may occur at any unusual location in the fetus and the placenta [3, 11, 13]. Umbilical cord teratomas derive from ectopic germ cells that migrate out of the wall of the invaginated gut into the connective tissue of the cord [9]. They rarely contain malignant tissue components [11, 13]. Similar to the present case, umbilical cord teratomas have both a solid and cystic nature, and are covered with skin. As the bowel loops are visualized hypoechoically in USG, it is important to differentiate the origin of the umbilical cord mass. It may be the cord itself or other herniated organs within exopmhalos, such as the liver or intestine [1, 8].

Umbilical cord teratomas tend to grow rapidly and may cause cardiac failure and fetal hydrops. If the teratoma is associated with the umbilical vessels or omphalocoele it may lead to rupture of the fetal cord [4, 11]. The mass diameter should therefore be followed closely and hydrops fetalis should be monitored.

Umbilical cord teratomas may be associated with other midline defects, such as exomphalos and bladder exstrophy [3, 8]. Exomphalos can also mimic or hide the umbilical cord teratoma [3, 5]. A detailed evaluation of umbilical cord and placenta should be performed in all fetuses, especially in fetuses with a diagnosis of exomphalos. Even though the sensitivity of the ultrasonography in screening anterior abdominal wall defects is high and the herniated fetal organs can be visualized, most cases of umbilical cord teratomas have an accurate diagnosis postnatally. Since associated anomalies were noted in nearly half of the cases (6/15), anatomical survey should be performed in presence of umbilical cord teratoma [4, 7, 8, 12]. In our case the fetus had no other anomalies and had a normal karyotype.

Differential diagnosis of a mass located in the cord also may include small acardiac twins, especially those of the amorphous type. Acardiac twins can be differentiated from umbilical cord teratomas by having an independent, although rudimentary, umbilical cord and a craniocaudal skeletal organization, whereas teratomas do not [6].

Fetal MRI provides the potential advantage of superior soft tissue characterization with better differentiation of the tumor compared with USG. Fast MRI sequences, such as T2-weighted fast spin-echo and half-Fourier single-shot fast spin-echo, have virtually eliminated the need for fetal premedication, with a concomitant improvement in image resolution and diminished blurring [10]. MRI was helpful for confirming our diagnosis.

A review of postnatally-diagnosed cases revealed that five of the 11 fetuses/newborns died due to associated malformations [12]. Only seven out of 15 fetuses (including our case) were alive and well in the literature [3, 4, 7, 8, 12]. The presence or absence of abdominal wall defect did not seem to affect the fetal viability. Although fetal Doppler evaluation was normal in USG examinations, the compression of the mass on the umbilical cord vessels as it enlarges may cause impaired blood flow and may be responsible for fetal demise. Since the most of the isolated cord teratoma cases in the literature are terminated or lost in utero there must be a clear consensus about the follow-up method. Nevertheless, close follow up should be planned for these cases, especially the ones with exomphalos, to continue antenatal sonographic surveillance of mass size, local vascular effects, and fetal systemic effects including high-output failure.

Conclusion

Exomphalos and cord teratoma have discriminative acoustic shadowing, nevertheless an appropriate prenatal diagnosis of teratoma can be challenging. Narrowing of the umbilical cord between the mass and the abdominal wall and the rapid growth pattern of the mass may lead to fetal demise. Close follow-up of these cases is recommended.