Erythema toxicum neonatorum This very common and completely benign condition usually arises in the first 2 days of life. It is seen in about 30% to 50% of healthy newborns and occurs less frequently in preterm infants. Rarely the onset occurs up to 14 days of age.

The lesions are erythematous macules, within which papules (Fig. 1-1) and pustules (Fig. 1-2) may develop. The trunk is the most common site, but all other body surfaces, except for the palms and soles, may be involved. In rare cases, these lesions may occur in plaques.

Erythema toxicum neonatorum Occasionally, this unimportant eruption must be differentiated from more serious infectious processes, such as neonatal herpes simplex. Tzanck smear of a pustule of erythema toxicum neonatorum will reveal numerous eosinophils but no multinucleated giant cells or bacteria.