Case 2: A Large Prenatally Undiagnosed Mass in a Preterm Infant, What Could It Be?

A 2.2-kg female infant is born at 28 4/7 weeks’ gestation to a 21-year-old gravida 1, para 0 woman with adequate prenatal care. During pregnancy, the mother is treated for Chlamydia with repeat negative cultures. She has negative serologies and a normal fetal ultrasonographic scan at 20 weeks’ gestation. Delivery is via cesarean section due to premature labor and frank breech presentation. At delivery, the infant is noted to have no respiratory effort and a large sacrococcygeal mass (Fig 1) . Positive pressure ventilation is started and the infant undergoes intubation 3 minutes after birth. Figure 1. Infant at delivery noted to have large sacrococcygeal teratoma. The admission physical examination findings are significant for a sacrococcygeal nodular, firm and nonpulsatile 20×30–cm mass, with minimal ulceration that is displacing the lower limbs anteriorly. Magnetic resonance imaging (MRI) of the pelvis shows a presacral mass with a large external component and relatively small internal component; the cephalad portion of the mass occurs at the level of L5, splaying the aortic bifurcation (Fig 2) . The infant’s vital signs are stable with minimal ventilatory support. Laboratory studies are positive for anemia (hemoglobin 11.4 g/dL [114 g/L]), a normal α-fetoprotein (AFP) level for gestational age (60,500 ng/mL [60,500 μg/L]), and a slightly elevated aspartate aminotransferase level (141 IU/L [2.35 μkat/L]). Figure 2. Magnetic resonance imaging scan of the pelvis showed a presacral mass (red arrow) with a large external component and relatively small internal component. On day 2 after birth, the infant develops hypotension and worsening respiratory failure; she is started on inotropes and high-frequency oscillation. The lesion becomes more tense and darker in color, concerning for intralesional hemorrhage. The infant also develops thrombocytopenia (platelets 66,000/μL [60×109/L]) and receives multiple platelet and red blood cell transfusions in preparation for surgery. Resection of the mass …