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Common Newborn Dermatoses
Key Points
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Papulopustular lesions on the palms and/or soles in the first month of life likely represent a self-limited inflammatory process such as eosinophilic pustular folliculitis or infantile acropustulosis—but scabies should be ruled out.
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Neonatal acne (a.k.a. cephalic pustulosis ) is typically multifactorial and self-limited. Treatment is not necessary, but topical agents aimed at reduction of the commensal yeast Malassezia can be beneficial.
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Evidence suggests that early use of emollients in infants at risk of developing atopic dermatitis may prevent later disease.
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Subcutaneous fat necrosis of the newborn is generally benign and self-limited but when extensive can cause hypercalcemia.
This chapter describes a group of cutaneous disorders commonly found in neonates. Most of these disorders are benign and are either self-limited or treated with ease. Recognition of these common neonatal dermatoses is important so as to distinguish them from more serious conditions, sparing patients unnecessary work-up and treatment. Each section includes common clinical features and presentation, notes on establishing the diagnosis (with a short differential diagnosis), the cause if known, and a brief discussion of basic treatment and prognosis.
Erythema Toxicum Neonatorum
Clinical Findings
Erythema toxicum neonatorum (ETN) is a benign inflammatory condition affecting newborns. Estimates of incidence range from 7% to 41%, and it is seen more commonly in white newborns with a higher birth weight and greater gestational age. The condition presents in the first 1 to 3 days after birth as irregularly shaped erythematous macules that can develop overlying vesicles or pustules ( Fig. 94.1 ). ETN most commonly affects the trunk but can involve the face and extremities as well. The palms and soles are typically spared. Affected infants are otherwise healthy. The lesions persist for 1 to 2 weeks and then spontaneously resolve without sequelae.
Diagnosis
The diagnosis is often clinical but can be further supported by the scraping of a pustule, smearing the contents onto a slide, and staining with Wright or Giemsa stain. This will reveal a large number of eosinophils. The differential diagnosis of ETN includes other benign entities such as transient neonatal pustular melanosis, miliaria, infantile acropustulosis, and eosinophilic pustular folliculitis. Additionally, infections such as folliculitis, candidiasis, impetigo, and herpes should be considered and ruled out. If a biopsy sample is obtained, histopathologic features include intraepidermal vesicles filled with eosinophils and a mixed intradermal inflammatory infiltrate localizing around the superficial pilosebaceous follicle.
Etiology
The cause of ETN remains unclear. Studies have shown the presence of inflammatory mediators, as well as increased eosinophil and macrophage activity in affected skin compared with unaffected skin. This has led to the theory that ETN could represent a cutaneous immunologic response to microbial colonization of the hair follicles after birth.
Treatment and Prognosis
No treatment is required for this benign condition. It is usually asymptomatic. Parents can be reassured and informed that the condition will spontaneously resolve in a matter of weeks. Prolonged courses or recurrence is rare.
Transient Neonatal Pustular Melanosis
Clinical Findings
Transient neonatal pustular melanosis is a benign, self-limited condition that presents at birth in affected infants. It is more common in African-American infants. There are three clinical phases of transient neonatal pustular melanosis. At birth, the neonate has very fragile and superficial 2- to 10-mm pustules located most commonly on the forehead, under the chin, on the lower back, and on the shins. These pustules are often wiped off during the initial cleaning after birth. Next, a fine collarette of scale is noted around the resolving pustule. Last, hyperpigmented brown macules develop at the site of the previous pustules ( Fig. 94.2 ). The first two phases usually last 1 to 2 weeks, but hyperpigmentation can persist for several months.
Diagnosis
Diagnosis is clinical, but it can be supported by a scraping from the pustule, with Wright staining of the contents. This will reveal a predominance of neutrophils. The differential diagnosis includes ETN, and these conditions can overlap. Additional considerations include miliaria, acropustulosis of infancy, and infectious diseases such as candidiasis, impetigo, and herpes, which should be ruled out.
Etiology
The underlying cause of transient neonatal pustular melanosis is unknown. Studies linking it with ETN suggest a similar cause.
Treatment and Prognosis
No treatment is required for this benign and self-limited condition. Parents should be informed that while the initial skin findings resolve quickly, the residual hyperpigmentation may take months to completely resolve.
Eosinophilic Pustular Folliculitis
Clinical Findings
Eosinophilic pustular folliculitis (EPF) is a vesiculopustular eruption that can occur in several distinct settings. The infantile form is relatively rare and presents with pruritic follicular lesions typically on the extremities or scalp, although truncal involvement is described ( Fig. 94.3 ). Crops of lesions will occur discretely, not in an annular array as in adults, and persist for days to weeks before resolving without sequelae. EPF tends to present somewhat later than erythema toxicum but has been described on the first day after birth.
Diagnosis
Diagnosis is clinical, and persistence past several weeks generally distinguishes EPF from erythema toxicum, although peripheral eosinophilia may be supportive. Histologic examination demonstrates an eosinophilic follicular infiltrate.
Etiology
The cause is unknown.
Treatment and Prognosis
Treatment is symptomatic and can include emollients, topical corticosteroids, and antihistamines. Topical indomethacin therapy has been used in refractory cases.
Acropustulosis of Infancy
Clinical Findings
Acropustulosis of infancy is a relatively uncommon pruritic, vesiculopustular rash that occurs on the hands and feet with spread to the wrists and calves. First described in 1979, this rash is closely related to preceding infections and infestations, with scabies preceding approximately 50% of cases. The eruption is most common in African-American, Hispanic, and Asian children and presents at less than 1 year of age. Crops of intensely pruritic vesicles and pustules appear on the hands and feet, persist for around 2 weeks, and then resolve ( Fig. 94.4 ). Frequent recurrences are the norm, with each eruption decreasing in intensity until eventual complete resolution around 2 to 3 years of age.
Diagnosis
Diagnosis is primarily clinical, and a history of preceding scabies can be quite helpful in making the diagnosis. If a biopsy sample is obtained, it shows necrolysis of the keratinocytes with intraepidermal pustules filled with neutrophils and eosinophils. The differential diagnosis includes scabies (concurrent infestation must be ruled out and treated if present), pustular psoriasis, coxsackievirus infection, eosinophilic folliculitis, and less likely, an allergic contact dermatitis.
Etiology
The cause of acropustulosis is unknown, but the condition is known to frequently follow prior scabies infestation or coxsackievirus infection.
Treatment and Prognosis
The recurrent episodes of acropustulosis of infancy will eventually resolve around 2 to 3 years of age, but episodes can be managed. Ruling out scabies and treating it if it is present should be a first step. Topical treatment with mid-potency to high-potency corticosteroids is effective for discrete episodes but will not help to prevent relapses. Historically, acropustulosis of infancy was treated with orally administered dapsone, but this is no longer frequently used because of the risk of hemolysis and methemoglobinemia in patients with glucose 6-phosphate dehydrogenase deficiency.
Milia
Clinical Findings
Milia are an extremely common benign entity, seen at birth in 40% to 50% of newborns. They are more common with longer gestations and in infants born to multigravidas. Milia (singular, milium ) are tiny, white monomorphic papules with a smooth surface. They can number from several to dozens. They are an entity distinct from miliaria, which is discussed next. Milia can be present anywhere on the body but occur most commonly on the face, predominantly on the forehead, cheeks, and chin ( Fig. 94.5 ).
Diagnosis
A useful diagnostic tool is expression of the milia contents, which will resemble a tiny, white pearl. This is the keratinocyte debris that forms the interior of the cyst. The differential diagnosis includes sebaceous hyperplasia, which would also present on the face but tend to be more yellow, and miliaria, which presents primarily on the body and in greater numbers with distinct clinical variants.
Etiology
Milia are tiny inclusion cysts that form in the epidermis. The epidermal tissue invaginates, often around a vellus hair, and forms a cyst with a wall of keratin-producing cells.
Treatment and Prognosis
Treatment of milia is not required. They tend to resolve spontaneously over several months. Of note, the presence of multiple large or persistent milia can rarely be associated with syndromes such as epidermolysis bullosa or orofaciodigital syndrome.
Miliaria
Clinical Findings
Miliaria is a benign rash due to obstruction of the eccrine duct occurring in the first 1 to 2 weeks of life, with rapid resolution within days. There are multiple variants depending on the location of the eccrine duct obstruction, with differing clinical presentations. Miliaria crystallina occurs when eccrine ducts within or below the stratum corneum are obstructed and causes small clear vesicles that can be easily wiped away ( Fig. 94.6 ). Miliaria rubra is caused by obstruction of the eccrine duct at the level of the epidermis and is thought to be related to overheating. This causes erythematous papules or papulopustules primarily on the head, neck, face, and trunk. Dermal inflammation contributes to the clinical presentation. Miliaria profunda is caused by occlusion of the eccrine duct at or below the dermal-epidermal junction and causes a mildly inflammatory papular eruption that is rare in newborns.
Diagnosis
The diagnosis of miliaria is made clinically, although scraping of a vesicle or pustule with subsequent Wright staining will reveal few to no cells in miliaria crystallina and lymphocytes in miliaria rubra. The differential diagnosis includes ETN, transient neonatal pustulosis, milia, eosinophilic folliculitis, and infectious entities. Recurrent episodes of pustular miliaria rubra could be a sign of the rare and potentially fatal condition type I pseudohypoaldosteronism, which is an inherited disorder of mineralocorticoid resistance leading to a salt-wasting crisis.
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