A 3½-month-old white boy presented with scaly, erythematous plaques on perioral and perianal skin and on the trunk and right thigh. The perioral eruption began 1 month before presentation and was treated with oral antibiotics and mupirocin ointment, without improvement. Two weeks later, a perianal eruption and diarrhea developed. Five days before presentation, an eruption developed on the thigh and trunk. The patient was born 5 weeks prematurely and weighed 2.5 kg at birth. He was totally breast-fed. At 3 months, he weighed 5.6 kg. He had been irritable and hard to console since birth, with no smiling and almost continuous crying while awake.