Neonatal Pustular Melanosis Clinical Presentation

Term or near-term infants are born with this condition. Pustules are usually uniformly sized and wipe off easily in the delivery suite.

The primary lesions in neonatal pustular melanosis progress through three stages of development. Initially, they appear as rather uniform round 2- to 4-mm nonerythematous pustules. They are not clear vesicles; rather, they contain milky, purulent exudate. The pustules rupture easily. They are frequently missed because they are superficial and are usually wiped off easily in the delivery suite when the newborn is cleansed of vernix. Pustules on the thicker areas of skin such as the knees or palms may persist for several days. ^{[7, 8]}

Next, a delicate collarette of thin white scale is left around the perimeter of each denuded pustule. Near-term infants, especially those delivered by cesarean delivery, may exhibit just the unbroken pustules, and term infants may have only macules remaining, usually with the telltale collarette of flaking epidermis.

Lastly, within hours of exposure to the terrestrial environment, the central pigmented brown macule becomes apparent. The macules are round, have smooth and distinct borders, and are frequently confused for freckles. They may be profuse or sparse and typically are found under the chin and on the neck, upper chest, back, and buttocks. Occasionally, the palms, soles, and scalp are affected.

When considering suspected neonatal pustular melanosis, the following should also be considered:

• Erythema toxicum neonatorum: These lesions are small papules on an erythematous base, contain predominantly eosinophils, and do not heal with postinflammatory hyperpigmentation.

• Congenital cutaneous candidiasis: The pustules are usually very inflamed and contain organisms on laboratory smear or biopsy.

• Impetigo: Pustules are inflamed and contain organisms on laboratory smear and culture.

• Congenital Langerhans cell histiocytosis: Widely distributed papules and pustules form adherent crusts, not frecklelike macules.

• Congenital varicella: Pustules are larger, numerous, generalized, and widely dispersed in the setting of an ill neonate with unstable vital signs.

• Miliaria: This characterized by clear vesicles (crystallina) or pustules (pustulosa) that erupt in a setting of hyperthermia.

• Herpes simplex: Lesions begin as vesicles, become turbid, and develop into pustules. The vesicles are grouped or clustered and contain multinucleated giant cells.

• Milia: This is characterized by firm, white, superficial, pin-head–sized papulelike cysts filled with keratin debris.

• Acropustulosis: The pustules predominate on the palms and soles and are not present at birth.