Transient neonatal pustular melanosis | |
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Other names | Transient neonatal pustulosis [1] and lentigines neonatorum [2] |
Transient neonatal pustular melanosis | |
Specialty | Dermatology, pediatrics |
Transient neonatal pustular melanosis (TNPM), also known as pustular melanosis, is a type of neonatal pustular eruption that is a transient rash common in newborns. 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. [3] The lesions are fragile and with no surrounding erythema. [3] This rash occurs only in the newborn stage, usually appearing a few days after birth, [4] but pigmented macules are sometimes already present at birth. [3] The rash usually fades over three to four weeks but may linger for up to three months after birth. [3] It can occur anywhere on the body, including the palms and soles. [4]
The cause of TNPM is unknown. It has been suggested that TNPM is merely a variant of erythema toxicum neonatorum [3] or a "precocious" form of erythema toxicum neonatorum. [5] No treatment is needed except for parental reassurance.
Transient neonatal pustular melanosis was initially described in 1961 as lentigines neonatorum [6] and as such was not fully distinguished from other similar rashes.
Transient neonatal pustular melanosis was clearly identified in 1976 by Ramamurthy et al. [6] [7]
The cause of TNPM is unknown. [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.
A smear of the pustular contents will show polymorphic neutrophils and occasional eosinophils on Wright's stain. [3]
On histopathology, the pigmented macules will show basal and supra-basal increase in pigmentation without any pigmentary incontinence. [3] Bacterial culture will be negative. [5]
Increased frequency of placental squamous metaplasia has been reported in the mothers of some of these infants. [8]
No treatment is needed except for parental reassurance. The rash spontaneously resolves, usually in three to four weeks, but the pigmented macules may linger for up to three months after birth. [3]
The incidence of TNPM is 0.6% in white infants and 4.4% in African-American infants in the United States. [9] This rash also generally has a higher incidence in non-African-American infants with skin of color. [9]
There is significant regional variation and the incidence can vary widely in other nations. For example, in Brazil, transient neonatal pustular melanosis occurs in 9.6% of all newborns. [10]
TNPM occurs equally in both sexes. [9]
Genetic influence is unlikely as it has been reported in only one of pairs of identical twins. [10]
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