A fetal case of a large sacrococcygeal teratoma

Rationale: Sacrococcygeal teratoma (SCT), derived from early embryonic pluripotent stem cells, is one of the most common neoplasms in fetuses. We report a case of a large mass in the fetal sacrococcygeal region detected by ultrasonography at a gestational age of 16+ weeks. Patient concerns: A 26-year-old woman, gravida 2, para 1, was referred to our hospital with a mixed echo protrusion (3.6 × 2.8 × 2.8 cm in the fetal sacrococcygeal region. Diagnoses: Ultrasound scan showed that the sacrococcygeal mass had grown to 7.1 × 5.8 cm. Magnetic resonance imaging revealed a large exophytic mass about 7.7 × 4.5 × 6.5 cm in the perineum of the fetus. Pathological examination revealed malignant SCT. Interventions: The patient was closely monitored and followed-up through prenatal examinations to assess the condition of the mother and child. Outcomes: The fetus was found dead in utero at 20-week gestation. The pregnant woman then induced labor. Lessons: SCT is a common germ cell tumor in fetuses. Attention should be paid to maternal and fetal conditions due to serious complications. Appropriate interventions during pregnancy and timely surgery after delivery are recommended.