January 11, 2008 — Clinicians who care for infants must be able to identify common skin lesions and counsel parents appropriately, according to a review article published in the January 1 issue of the American Family Physician. The study authors summarize the presentation, prognosis, and treatment of the rashes most often presenting during the first 4 weeks of life.

"A newborn's skin may exhibit a variety of changes during the first four weeks of life, write Nina R. O'Connor, MD, from the Chestnut Hill Hospital Family Practice Residency Program in Philadelphia, Pennsylvania, and colleagues. "Most of these changes are benign and self-limited, but others require further work-up for infectious etiologies or underlying systemic disorders. Nearly all of these skin changes are concerning to parents and may result in visits to the physician or questions during routine newborn examinations."

Transient vesiculopustular rashes that can be diagnosed clinically, based on their distinctive appearances, are erythema toxicum neonatorum, acne neonatorum, and transient neonatal pustular melanosis.

The most common pustular eruption during the first month of life is erythema toxicum neonatorum, affecting 40% to 70% of newborns. Typical lesions are erythematous, 2- to 3-mm macules and papules that evolve into pustules on the face, trunk, and proximal part of the limbs, each surrounded by a blotchy area of erythema.

Acne neonatorum, which is present in nearly one fifth of newborns, is characterized by closed comedones on the forehead, nose, and cheeks. Other locations, as well as development of open comedones, inflammatory papules, and pustules, are less common.

Transient neonatal pustular melanosis is a vesiculopustular rash affecting 5% of black newborns and less than 1% of white newborns. Unlike erythema toxicum neonatorum, transient neonatal pustular melanosis lesions have no surrounding erythema; rupture easily; and affect all areas of the body, including the palms and soles.

When rashes are accompanied by signs of systemic illness or unusual presentations, infants should be evaluated for Candida, viral, and bacterial infections.

In the newborn, immaturity of skin structures may give rise to milia and miliaria. Heat rash, or miliaria rubra, usually improves with cooling measures. Milia, present in nearly half of newborns, are 1- to 2-mm pearly white or yellow papules caused by keratin retention within the dermis. They usually disappear spontaneously within the first month of life but may persist into the second or third month, so parents should be reassured about their benign, self-limited course.

Miliaria results from sweat retention caused by partial closure of eccrine structures, occurs in up to 40% of infants, and usually appears during the first month of life.

Seborrheic dermatitis, characterized by erythema and greasy scales, is highly prevalent during the first 4 weeks of life, and it needs to be differentiated from atopic dermatitis. Seborrheic dermatitis, or "cradle cap," occurs most commonly on the scalp, but it may also affect the face, ears, and neck. Management of seborrheic dermatitis usually consists of parental reassurance and observation, but tar-based shampoo, topical ketoconazole, or mild topical steroids may be required for treatment of severe or persistent cases.

Features that help to differentiate seborrheic and atopic dermatitis in infancy include age at onset, which is usually within the first month, vs after 3 months of age, respectively. The course of seborrheic dermatitis is self-limited and responds to treatment, whereas atopic dermatitis responds to treatment but often relapses. Seborrheic dermatitis affects the scalp, face, ears, neck, and diaper area, and atopic dermatitis affects the scalp, face, trunk, extremities, and diaper area. Pruritus is infrequent with seborrheic dermatitis but is highly prevalent with atopic dermatitis.

Specific clinical recommendations and their corresponding level of evidence rating are as follows:

• Infants who have vesiculopustular rashes and who appear ill should be tested for Candida, viral, and bacterial infections (level of evidence, C).
• Although acne neonatorum usually resolves within 4 months without scarring, resolution of severe cases may be facilitated by 2.5% benzoyl peroxide lotion (level of evidence, C).
• Miliaria rubra, or heat rash, typically resolves with avoidance of overheating, removal of excess clothing, and treatment with cool baths and air conditioning (level of evidence, C).
• Infantile seborrheic dermatitis generally resolves with conservative treatment, such as petrolatum, soft brushes, and tar-containing shampoo (level of evidence, C).
• Topical antifungals or mild corticosteroids may be used to treat seborrheic dermatitis that is refractory to conservative management (level of evidence, B).

"If seborrheic dermatitis persists despite a period of watchful waiting, several treatment options exist," the review authors write. "Tar-containing shampoos can be recommended as first-line treatment. Selenium sulfide shampoos are probably safe, but rigorous safety data in infants is lacking. The use of salicylic acid is not recommended because of concerns about systemic absorption."

The review authors have disclosed no relevant financial relationships.

Am Fam Physician. 2008;77:47-52.

Clinical Context

Study Highlights

• Transient rashes:
  • Newborn vascular physiology is responsible for 2 types of transient skin color changes: cutis marmorata and harlequin color change.
  • Cutis marmorata is a reticulated mottling symmetrically affecting the trunk and extremities in response to cold and resolves with warming, with no treatment indicated.
  • Harlequin color change occurs suddenly (within 30 seconds to 20 minutes) with the infant lying on his or her side and affects up to 10% of newborns during day 2 to 5, continuing to 3 weeks. No treatment is indicated.
  • Erythema toxicum neonatorum is most common in term infants (40% - 70% incidence) weighing more than 2500 g and typically consists of erythematous 2- to 3-mm macules and papules that evolve into pustules with a flea-bitten appearance. Cytologic examination shows eosinophilia, with no treatment indicated.
  • Transient neonatal pustular melanosis affects 5% of black newborns and less than 1% of white newborns, with rupture and scaling of lesions affecting all areas of the body and resolution within 3 to 4 weeks. No treatment is indicated.
  • Acne neonatorum occurs in up to 20% of newborns, with closed comedones on the forehead, nose, and cheeks from stimulation of sebaceous glands and resolution within 4 months. No treatment is indicated except for extensive persistent cases, which can be treated with 2.5% benzoyl peroxide (skin testing should occur first).
  • Milia are 1- to 2-mm pearly white or yellow papules caused by keratin retention affecting 50% of newborns on the forehead, cheeks, nose, and chin and other surfaces and are benign and self-limiting.
  • Miliaria results from sweat retention and immaturity of skin surface with crystalline and rubra the most common manifestations, both of which are benign. Management consists of avoidance of overheating and treatment with cooling measures.
  • Seborrheic dermatitis is characterized by erythema and greasy scales on the scalp, flexural folds, or diaper area and is usually self-limiting, lasting weeks to months, with 85% of children free of skin disease at follow-up.
  • Treatment begins with soft brush to remove scales, or use of emollient or shampoo and vegetable oil to remove scales from the scalp.
  • More severe cases can be treated with tar-containing shampoos, mild corticosteroid cream, or antifungal shampoos. Ketoconazole may prevent recurrence.
  • Salicylic acid should be avoided because of the risk for systemic absorption.
• Infectious causes:
  • Group A or B Streptococcus bacterial infection is usually associated with systemic signs of sepsis. Gram stain of intralesional contents for Listeria monocytogenes or Pseudomonas aeruginosa will show polymorphic neutrophils with elevated band count and positive blood culture results.
  • Candidal fungal infection presents within 24 hours of birth if congenital or within 1 week if acquired during delivery. Potassium hydroxide preparation of intralesional contents shows pseudohyphae and spores, with thrush as a common condition.
  • Spirochetal infection with syphilis is rare, with lesions on the palms and soles and should be suspected if results of maternal tests are positive.
  • Among viral infections, cytomegalovirus, herpes simplex, and varicella zoster are the most common, and intralesional contents should be examined.
  • Results of the Tzanck test are positive for multinucleated giant cells in herpes simplex and varicella zoster.

Pearls for Practice

• In newborns, most rashes are transient and benign, and they result from physiologic skin changes.
• Management of most transient newborn rashes is observation with no treatment, whereas rashes resulting from infection should be excluded for atypical or systemic presentations.

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