It is vesiculopustular rash made up of 1–3 mm fluid-filled lesions that rupture, leaving behind a collarette of scale and a brown macule.

Transient neonatal pustular melanosis was initially described in 1961 as lentigines neonatorum[6] and as such was not fully distinguished from other similar rashes.

[3] It has been suggested that TNPM is merely a precocious form of erythema toxicum neonatorum based on the similar histopathology.

[5] Transient neonatal pustular melanosis is diagnosed clinically, based on appearance alone, with no need for special testing.

Proper identification is important to distinguish it from other serious, infectious neonatal diseases[3] and to help avoid unnecessary diagnostic testing and treatments.