[The mandatory diaper peek in newborn girls]

We present a 3 day old girl born at term presenting with an interlabial, cystic mass. Pregnancy, delivery and routine antenatal screening were unremarkable. The smooth lesion was located in the anterior half of the vulva, covered with thin vessels. The medially displaced urethra and the medio-posteriorly displaced hymen were identified. Voiding was not impaired. We discuss the differential diagnosis of vulvar masses in the newborn girl. A thorough clinical examination must be the standard of care of pediatric examinations in infants.