Transient Neonatal Pustular Melanosis

Background

Neonatal skin lesions are common. Differentiation of the nonsignificant from more serious clinical entities is important.^{[1, 2, 3, 4]} Transient neonatal pustular melanosis, a benign idiopathic skin condition mainly seen in newborns with skin of color, has distinctive features characterized by vesicles, superficial pustules, and pigmented macules. The lesions of transient neonatal pustular melanosis are present at birth. They occur on the chin, neck, forehead, chest, buttocks, back, and, less often, on the palms and soles.^{[5, 6]} The vesicles and pustules rupture easily (see the image below) and resolve within 48 hours. The brown macules may persist for several months.^{[5, 7]}

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Ruptured pustules and vesicles with remaining characteristic collarette of scale and brown hyperpigmented macules. Courtesy of Anthony J. Mancini, MD.....

See 13 Common-to-Rare Infant Skin Conditions, a Critical Images slideshow, to help identify rashes, birthmarks, and other skin conditions encountered in infants.

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Etiology

The etiology of transient neonatal pustular melanosis is unknown. No familial predisposition has been identified for transient neonatal pustular melanosis.

Increased frequency of placental squamous metaplasia has been reported in the mothers of some of these infants, although this relationship has not been demonstrated in any large trial.^[8]

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Epidemiology

US frequency

Previously published incidence rates for transient neonatal pustular melanosis are 0.6% in white infants and 4.4% in African American infants. The overall rate has been reported as 2.2%.^[9] Transient neonatal pustular melanosis is more common in term-gestation infants.^[10] Transient neonatal pustular melanosis has also been seen in non–African American infants with skin of color, although the literature is sparse.

Race

Transient neonatal pustular melanosis may occur in as many as 5% of African American newborns and less than 0.6% of white infants.

Sex

Transient neonatal pustular melanosis occurs equally in both sexes.^[5]

Age

Transient neonatal pustular melanosis is present at birth

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Prognosis

Transient neonatal pustular melanosis is a benign, asymptomatic, and self-limited skin eruption with no associated mortality or morbidity. The prognosis for transient neonatal pustular melanosis is good. The vesicles and pustules usually resolve within 48 hours,^[11] while the brown macules usually fade over 3-4 weeks but may persist for several months.^[12]

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Patient Education

Reassure the parents that transient neonatal pustular melanosis is a benign, self-limiting condition.

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History

Often, only pigmented macules are present at birth, in which case the pustular phase may have occurred in utero. Skin findings can be correlated with gestational age at birth. Post-term infants are more likely to have the late finding of pigmented macules. No systemic symptoms are associated with the skin lesions of transient neonatal pustular melanosis.^{[6, 13]}

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Physical Examination

Transient neonatal pustular melanosis is characterized by vesicles, superficial pustules, and pigmented macules.

Because of the fragile nature of the superficial pustules, most are broken during the initial drying or cleansing of the newborn. Intact lesions may remain in more protected areas such as beneath the chin, in the axillae, or in the groin. The vesicles and pustules may desquamate during the neonate's first bath, leaving characteristic white collarettes of scale and brown macules. The vesicopustules resolve within 24-48 hours.^[9] The hyperpigmented macules usually fade within 3-4 weeks, although full resolution may take several months.^[12] Note the image below.

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Ruptured pustules and vesicles with remaining characteristic collarette of scale and brown hyperpigmented macules. Courtesy of Anthony J. Mancini, MD.....

Depending on the time of the examination in the neonatal period, the vesicles, pustules, and/or pigmented macules may be found predominantly on the chin, neck, or forehead; behind the ears; or on the trunk, palms, and soles.^[10]

The lesions are 2-10 mm in diameter. Vesicles and pustules are usually 2-4 mm and are often filled with milky fluid. These lesions lack surrounding erythema.^{[7, 12]}

No systemic signs or symptoms are associated with the skin eruptions.

Papules are not seen in transient neonatal pustular melanosis, but they may be seen in neonates with erythema toxicum neonatorium, acne neonatorum, or miliaria. The vesiculopustular lesions may be similar to lesions seen in acropustulosis. Acropustulosis is also more common in African American infants, but it has a male predominance and pruritic lesions cluster on the palms and soles.^[11]

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Laboratory Studies

The diagnosis of transient neonatal pustular melanosis is usually made by clinical examination.

A Tzanck smear with a cellular stain (eg, Wright-Giemsa stain) or Gram stain of the contents of a pustule reveals a predominance of neutrophils and occasional eosinophils and cellular debris.^{[5, 11, 12]} No evidence of bacterial, yeast, or viral infection is found. Gram stain preparations for bacteria are negative. Blood and skin culture results are negative.

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Histologic Findings

Vesicopustules of transient neonatal pustular melanosis show intracorneal and subcorneal collections of neutrophils with occasional eosinophils, mild acanthosis, and some intraepidermal edema. Occasionally, fragmented hairs may be seen in the blister cavity. Dermal inflammatory infiltrate is extremely minimal. Pigmented macules reveal a basket-weave, slightly hyperkeratotic stratum corneum^[9] together with hypermelanosis in the epidermal basal cells, but no melanin in the dermis.^{[8, 14]}

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Medical Care

No specific therapy is indicated for transient neonatal pustular melanosis.^{[5, 10, 11]}

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Prevention

Contagious isolation is unnecessary for transient neonatal pustular melanosis.

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Medication Summary

No medication is necessary for transient neonatal pustular melanosis.

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