February 2006

A seven-day-old male infant was noted to develop several vesicular lesions over his entire body including the palms and soles. The lesions were fairly superficial, were discrete, and had minimal to no erythema surrounding them. The infant had a normal temperature and was feeding well. The infant was full term and delivered by spontaneous vaginal delivery. His maternal history was negative for infectious diseases, and there were no ill contacts. What do you think is the diagnosis?

Answer

This infant had transient neonatal pustular melanosis (TNPM).

This disorder is noted at birth or shortly thereafter. It occurs in 4.4% of black infants while only 0.2% of white infants are affected. Typically, the vesiculo-pustular lesions are located on the neck, face and trunk. The lesions can also be noted on the palms and soles. Hyperpigmented macules may occur following the resolution of a pustule in the same location. Hyperpigmented macules can also be noted right at birth or without a history of a preceding pustule.

The pustules are easily ruptured and are sterile when a culture of the fluid is obtained. When the contents are examined microscopically using a Wright’s stain, neutrophils are seen.

Differential diagnoses included:

• Erythema toxicum neonatorum — erythema toxicum papules are usually on the trunk and have a surrounding erythema and/or wheals (flea-bitten rash). The lesions spare the palms and soles. Erythema toxicum neonatorum is much more common than TNPM. A skin biopsy would show eosinophils.
• Miliaria crystallina — this disorder can also present with superficial vesiculo–pustular lesions. The lesions tend to be localized in intertriginous areas or on the face and scalp. Occluded areas have an increased susceptibility to form lesions. A skin biopsy will show lymphocytes in the eccrine ducts.
• Neonatal herpes simplex – the vesiculo-pustular lesions are arranged in groups and are not as superficial as TNPM. The infant may have symptoms, including feeding intolerance and temperature instability. Ulcers can develop, however, in TNPM, ulcers do not develop.
• Congenital candidiasis — the infants with congenital candidiasis have more scale and erythema, and the rash tends to have a more patchy appearance.
• Eosinophilic pustular folliculitis — this tends to be seen in older children and the pustules contain eosinophils. The lesions are follicular-centered and the most common location is the scalp.
• Incontinenti pigmenti — is a genetic skin disorder that is characterized by vesicular lesions arranged in a linear pattern. IP is transmitted as an X-linked dominant disorder and greater than 95% of the patients with this diagnosis are girls. The other stages seen on the skin with IP are verrucous and hyperpigmented.

No treatment is necessary for transient neonatal pustular melanosis. The pustules resolve spontaneously over several days and the hyperpigmented macules resolve over several months.

Source: Patricia Treadwell, MD

For more information:

• Mengesha YM, Bennett ML. Pustular skin disorders: diagnosis and treatment. Am J Clin Dermatol 2002;3:389-400.
• Buckley DA, Munn SE, Higgins EM. Neonatal eosinophilic pustular folliculitis. Clin Exp Dermatol 2001;26:251-255.
• Treadwell PA. Dermatoses in newborns. Am Fam Physician 1997;56:443-450.
• Wagner A. Distinguishing vesicular and pustular disorders in the neonate. Curr Opin Pediatr 1997;9:396-405.