A newborn presented on the first day of life with a chest mass found on initial examination in the nursery (Figure 1). She was born at 38.3 weeks via spontaneous vaginal delivery after an uncomplicated pregnancy to a 35-year-old, G3, now P2 mother with no significant medical history. Results of maternal prenatal laboratory tests were all unremarkable. She received regular prenatal care, and routine ultrasonography revealed no anomalies. The Apgar scores were 9 at 1 minute and 9 at 5 minutes. No resuscitation was required in the delivery room. The newborn was already breastfeeding well, voiding, and stooling by the time of the initial examination. Physical examination revealed a 3.5 × 4-cm mobile mass on the right lateral trunk at the midaxillary line at levels approximately T4 to T6. The mass was firm and round, although when palpated it was not homogeneous or smooth. There was no discoloration of the overlying skin. Results of the remainder of the physical examination were normal.