How do erythema toxicum neonatorum and transient neonatal pustular melanosis differ?

Erythema toxicum neonatorum (ETN) and transient neonatal pustular melanosis (TNPT) are both benign vesiculopustular disorders of unknown etiology that present during the first few days of life. ETN does not demonstrate a racial predilection and is very common, with up to 20% of neonates being affected. Clinically, it usually presents as macular erythema that usually affects the face initially; approximately 10% to 20% of cases develop pustules within the center of the areas of macular erythema. Biopsies of the pustules demonstrate an acute superficial folliculitis composed primarily of eosinophils. Peripheral eosinophilia may be present in 20% of cases. The lesions resolve without permanent sequelae in 7 to 10 days. Epidemiologically, TNPT differs from ETN in that it occurs in about 5% of black neonates but in ,1% of white neonates. Clinically, it presents as vesiculopustules that are not associated with surrounding erythema. The vesiculopustules resolve within 48 hours and are followed by hyperpigmented macules that may take 3 months to resolve. In contrast to ETN, biopsies demonstrate subcorneal pustules that are not follicular based, and the primary inflammatory cells are neutrophils. Peripheral eosinophilia is absent. Both conditions are benign and self-limited. Treatment is not recommended.

Marchini G, Ulfgren AK, Lore K, et al: Erythema toxicum neonatorum: an immunohistochemical analysis, Pediatr Dermatol 18:177–187, 2001.

Merlob P, Metzker A, Reisner SH: Transient neonatal pustular melanosis, Am J Dis Child 136:521–522, 1982.