Dichorionic diamniotic twins were born at 37 weeks of gestation by cesarean section to a 34-year-old primigravid Japanese woman because the first twin was in breech presentation. The mother had been diagnosed with pemphigus vulgaris prior to her pregnancy. In addition to a high antidesmoglein 3 autoantibody titer, flaccid bullae and erosions on both of the twins’ lips and in their oral cavities at 13 days of age led to the diagnosis of neonatal pemphigus vulgaris. This case highlights the need for awareness that pemphigus
vulgaris may not occur immediately after birth.