Intraplacental Mature Cystic Teratoma

Placental teratomas are benign germ cell tumors composed of mature tissues from multiple germ layers. They may mimic a cardiac fetus but lack organized fetal structures and an umbilical cord.

A 25-year-old G5P1224 woman delivered at 34 weeks of gestation following PPROM. Examination of the placenta revealed a 3.5 cm intraplacental, mixed solid and cystic lesion without a pedicle. Histology showed mature tissues including cartilage, ganglion cells, choroid plexus, and ciliated epithelium, consistent with a mature cystic teratoma.

The absence of an umbilical cord and embryonic organization distinguishes a mature cystic teratoma from an acardiac twin. Unlike the TRAP sequence, placental teratomas occur in singleton pregnancies, carry no recurrence risk, and pose no threat to fetal or maternal health. Accurate diagnosis is crucial to avoid misclassification and unnecessary intervention.