This very common and completely benign condition usually arises in the first 2 days of life. It is seen in about half of healthy newborns and occurs less frequently in preterm infants. The lesions are erythematous macules, within which papules and pustules may develop. The trunk is the most common site, but all other body surfaces, except for the palms and soles, may be involved. Occasionally' these lesions may occur in plaques. The eruption shown in Fig. 1-1 began 2 hours after delivery and involved the face and trunk. The eruption shown in Fig. 1-2 was unusual in that it was so widespread and vesiculopustular. 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. Occasionally, peripheral eosinophilia is also present. The cause of this condition is not known, and it resolves spontaneously within 10 days. No treatment is required.
This is a benign neonatal dermatosis that is most common among African-American infants. The original lesion is a vesiculopustule, which may be present at birth. This small blister quickly ruptures and leaves a typical collarette of superficial scale. Both intact pustules and collarettes are seen in the newborn in Fig. 1-3 and Fig. 1-4. Figure 1-4 shows the brownish-pigmented macules that may develop at the site of resolving lesions. These macules may be sparse or numerous and resolve without residua over a period of several weeks to several months.
In some infants, the pustule and collarette stages seem to occur in utero, and the sole cutaneous manifestations are the typical macules. Lesions of transient neonatal pustular melanosis favor the forehead, neck, chin, and lower back but may be very widespread and may involve the palms and soles (Fig. 1-6). Scraping the base of an unroofed pustule reveals polymorphonuclear leukocytes but no bacteria, pseudohyphae, or multinucleated giant cells. A biopsy of a pustule, which is rarely necessary, shows an intraepidermal collection of polymorphonuclear leukocytes.