The critical interface between body and environment is amply demonstrated by the phenotype of newborn skin. The initial management of a newly born infant includes drying the baby to prevent heat loss and an informed assessment of skin color, perfusion, and integrity. Pathologic processes visible on the skin surface range from general signs of internal organ dysfunction (cyanosis, pallor, jaundice) to clinical evidence of specific diseases (vesicles, petechiae). Cutaneous characteristics are routinely used as determinants of gestational age (breast buds, plantar creases, desquamation).7 The definitive organ of mammals, the mammary gland, is an ectodermally derived cutaneous structure.77 Maternal-infant bonding is, in large part, a complex dynamic interaction between skin surfaces.71 At birth, the skin of the term infant must perform multiple functions critical for survival in an extrauterine environment (Box 102-1).35 Many of these functions depend on structural development of the skin during the last trimester of pregnancy. The development of a competent epidermal barrier, for example, is essential for temperature regulation, maintenance of fluid homeostasis, infection control, and prevention of penetration of environmental toxins and drugs. The epidermal permeability barrier primarily resides in the outermost layer of the epidermis, the stratum corneum. This layer, approximately one fourth the thickness of a sheet of paper, develops in utero during the third trimester of pregnancy in conjunction with a protective mantle of vernix caseosa. Extremely low birth weight preterm infants (<1000 g birth weight) lack a well-developed stratum corneum and pose special problems for newborn care. The stratum corneum is necessary for the adherence of thermistors, cardiorespiratory monitors, and endotracheal tubes and forms the primary environmental interface with caregivers and parents. Box 102-2 gives a summary of general principles of skin care drawn from the literature.19,62 In addition to prematurity, there are a host of diseases and disorders of the fetus and newborn that present with cutaneous manifestations. The advantage of the accessibility of the skin to physical examination is counterbalanced by the extreme structural and functional diversity of this organ. The caregiver must distinguish benign and transient lesions of newborn skin, such as erythema toxicum, from potential life-threatening diseases such as herpes simplex neonatorum. A basic understanding of the structural development of the skin, as well as the multiple functions subserved by the skin during transition to extrauterine life, is of basic importance to all newborn caregivers.35,36 Human skin has two distinct but interdependent components—the epidermis and the dermis (Figure 102-1). The epidermis has marked regional variations in thickness, color, permeability, and surface chemical components. It consists of a highly ordered, compact layering of keratinocytes and melanocytes. Traditionally, the epidermis is segmented into distinct structural and functional compartments called the stratum germinativum (basale), stratum spinosum, stratum granulosum, and stratum corneum (see Figure 102-1). Intermixed is a third distinct cell type, the Langerhans cell, which is derived from bone marrow precursors and migrates into the primitive epidermis. The process of cutaneous morphogenesis can be divided into embryonic and fetal periods (Figure 102-2).37,41 This transition, which occurs at approximately 2 months or 60 days, is an important time in skin development because many critical morphogenetic events occur during this transitional period. Between 30 and 40 days of development, the embryonic skin consists of a two-layered epidermis: the basal layer, associated with the basal lamina, and the periderm, which serves as a cover and a presumptive nutritional interface with the amniotic fluid. The basal layer includes cells that give rise to the future definitive epidermis, whereas the periderm is a transient layer that covers the embryo and fetus until the epidermis keratinizes at the end of the second trimester. Basal cells join with each other and peridermal cells by a relatively few desmosomes but do not yet form hemidesmosomes with the basement membrane. Small numbers of keratin intermediate filaments are associated with these junctions. Matrix adhesion of the embryonic epidermis is likely mediated by actin-associated α6β4 integrin.37,61 At the time of embryonic-fetal transition (60 days’ gestation), the epidermis begins to stratify, forming an intermediate layer of cells. These young keratinocytes still contain a high volume of glycogen in their cytoplasm and produce large amounts of intermediate filaments in association with the desmosomes. At this time, new keratins are identifiable as markers of differentiation, as is the pemphigus antigen, which is detectable on the cell surface. These cells, unlike adult spinous cells, remain proliferative and continue to express epidermal growth factor receptors on their surfaces. Two to three additional layers of intermediate cells are added during the second trimester. These cells show a progressive increase in the number of keratin filaments, but do not further differentiate until the onset of keratinization in the interappendageal epidermis around 22 to 24 weeks’ gestation.41 The appendages derive from embryonic invaginations of epidermal germinative buds into the dermis.42 They include hair, sebaceous glands, apocrine glands, eccrine glands, and nails. The arrector pili muscle is attached to the hair follicle. Lanugo (i.e., fine, soft, immature hair) frequently covers the scalp and brow of the premature infant. The scalp line may be poorly demarcated, and lanugo also may cover the face. Scalp hair is usually somewhat coarser and matures earlier in dark-haired infants. There are sex differences in hair growth; boys’ hair grows faster than girls’ hair. In both sexes, scalp hair growth is slower at the crown. The normal pattern of hair growth is disturbed in many chromosomal disorders. Recent evidence supports a genetic link between the formation of clockwise posterior parietal hair whorls and specific (right) handedness of the individual.54 This finding supports an unexpected association between gene-based hair patterning and human brain development that warrants further substantiation. Supporting the significance of the skin-brain connection, recent evidence has shown the human hair follicle can synthesize cortisol de novo and is a functional equivalent of the hypothalamic-pituitary-adrenal axis.47 The eccrine sweat glands are coiled structures that form during the first trimester as a downgrowth from epidermal cellular clones. No new glands are formed after birth. They are distributed over the entire body surface and are innervated by sympathetic cholinergic nerves. During the first 24 hours of life, term infants usually do not sweat; on approximately the third day, sweating begins on the face. Palmar sweating begins later. Thermal sweating as a function of body or environmental temperature should be distinguished from emotional sweating associated with crying or pain.91 The latter is best assessed on the palms and soles. The sebaceous glands differentiate primarily from the epithelial portion of the hair follicle at approximately 13 to 15 weeks of life and almost immediately produce sebum in all hairy areas.100 The glands develop as solid outpouchings from the upper third of the hair follicle. These solid buds become filled with liquid centrally where the cells disintegrate; acini and ducts develop, opening most frequently into the canals between the hair follicle wall and hair shaft. Ectopic glands occur occasionally on the lips, buccal mucosa, esophagus, and vagina. Surprisingly little is known about the regulation of the rapid growth and activity of sebaceous glands up to and immediately after birth. Hypothetically, secretion by the fetal adrenal gland of weak androgens such as dehydroepiandrosterone (DHEA) is followed by intra-sebocyte conversion to testosterone and production of products of the pilosebaceous unit such as vernix caseosa.100 This hypothesis remains to be fully tested, but it has the singular advantage of functionally integrating two disparate and unexplained facts; that is, the mutual hyperplasia of the sebaceous gland and the adrenal cortex during the latter half of gestation in the human fetus. Androgens are the only hormones that unequivocally have a stimulating effect on the sebaceous glands; estrogens depress their growth. Between 2 months and 2 years, the sebaceous glands of the normal infant begin a period of quiescence that lasts until puberty. Vernix caseosa, a unique material that coats the fetal skin surface during the last trimester of pregnancy, contains lipids of sebaceous origin as well as numerous water-laden fetal corneocytes. A growing body of evidence supports the hypothesis that vernix caseosa participates in regionally “waterproofing” the skin surface, thereby allowing cornification to occur, initially around the hair follicles, and then over the interfollicular skin.39 A better understanding of vernix caseosa and fetal sebaceous gland physiology is biologically relevant and may be applicable to care of the very low birth weight infant and to clinical situations in which the epidermal surface is inadequately developed, burned, or traumatized. Physiologically, vernix is a hydrophobic material containing wax esters, cholesterol, ceramides, and squalene in addition to other minor lipid components. Vernix has high water content (≈80%), with the water primarily distributed within flat, polygonal, cornified squames. As term approaches, vernix detaches from the fetal skin surface under the influence of pulmonary surfactant and is swallowed by the fetus. In close analogy to breast milk, vernix contains multiple molecules associated with the innate immune system, including lysozyme, lactoferrin, and defensins, as well as antioxidants such as alpha tocopherol.38 Vernix possesses both emollient (moisturizing) and cleansing functions. Thus at birth the human infant is covered with a complex material possessing endogenous anti-infective, antioxidative, moisturizing, and cleansing capabilities. Extreme prematurity, as well as postmaturity, is associated with diminished vernix on the skin surface at birth. The fetal dermis acquires some of the characteristics of adult dermis around 20 weeks’ gestation. However, it is only in the more mature fetus that the true structural and biochemical qualities of the newborn dermis are detectable. The dermis contains three identifiable zones: the region adjacent to the basement membrane, the papillary dermis, and the reticular dermis (see Figure 102-1). The superficial dermis has finer collagen fibers and is biochemically more active than the deeper zone. The papillary dermis also is more susceptible to light injury and elastic tissue degeneration than the reticular dermis. The dermis has a symbiotic relationship with, and may exert a controlling influence on, the epidermis. It is a metabolically active tissue that contains fibrous elements, amorphous ground substance, free cells, nerves, blood vessels, and lymphatics. The vascular network supplying the skin develops in early embryonic life from the mesoderm.86 In 60- to 70-day-old fetuses, there are two vascular networks: a superficial one that appears to correspond to the subpapillary plexus of adult skin and a deeper network that represents the deep reticular vascular network of adult skin. New capillary beds organize to supply the developing epidermal appendages from the fifth month of gestation. These two networks persist into the newborn period; however, the arrangement of vessels remains unstable for the first year of life, and further organization of the vascular network occurs postnatally. Vasomotor tone is controlled by a delicate and complex series of neural and pharmacologic mechanisms that involve the sympathetic nervous system, norepinephrine, acetylcholine, and histamine and may involve serotonin, vasoactive polypeptides, corticosteroids, and prostaglandins. The physiologic requirements of skin vary considerably; skin blood flow ranges from 0.1 to 150 mL/mm3 of tissue per minute.86 Special neurologic structures include a dense perifollicular nerve network with exquisite tactile sensory properties and mucocutaneous end organs highly concentrated in erogenous zones. Meissner tactile organs are found in newborn skin as undeveloped structures that mature after birth. Merkel corpuscles probably govern two-point tactile discrimination on palms and fingertips; they are disk-shaped terminals that are seen during the 28th week of fetal life. After birth, these receptors undergo little alteration. Vater-Pacini corpuscles are found around the digits, palms, and genitals; they are fully formed and numerous at birth.35 The arrector pili muscles are innervated by sympathetic nerves, and norepinephrine acts as the neurotransmitter. The eccrine glands are innervated by sympathetic fibers, but acetylcholine acts as the neurotransmitter. Parasympathetic fibers may accompany the sensory nerves in the vessel walls and cause vasodilation. The axon reflex is poorly developed in the newborn; in the neonate of low birth weight, axon-reflex sweating may be difficult to elicit.85 This section provides a cursory synopsis of normal and abnormal aspects of newborn skin. An accurate description of primary and secondary skin lesions underlies the proper identification of skin condition and whether appropriate treatment is needed. Tables 102-1 and 102-2 describe the basic lesional morphology of infant skin with specific examples. More definitive treatises on normal skin structure, function, development, and specific disease states are available.25,36 The remainder of this chapter delineates specific conditions of newborn skin ranging from transient lesions to definitive cutaneous diseases and diagnostic categories. TABLE 102-1 *Lesions arise de novo and are therefore most characteristic of the disease process. Modified from Yan AC, et al. Lesional morphology and assessment. In: Eichenfeld LF, et al, eds: Neonatal and infant dermatology, Philadelphia: Saunders; 2013, Chapter 11. TABLE 102-2 *Lesions arise as characteristic modifications of primary lesions through environmental interaction (e.g., drying) or subject interaction (e.g., scratching). Modified from Yan AC, et al. Lesional morphology and assessment. In: Eichenfeld LF, et al, eds. Neonatal and infant dermatology. Philadelphia: Saunders; 2013, Chapter 11. A number of benign and transient lesions of the skin are commonly observed in a normal nursery population.49,76 It is important for the infant caregiver to distinguish such ephemeral lesions from significant life-threatening diseases with cutaneous manifestations. Approximately 8% of infants have multiple, white, 1-mm cysts (i.e., milia) scattered over the cheeks, forehead, nose, and nasolabial folds. These milia may be few or numerous, but they frequently occur in clusters. Milia are often confused with the more common condition of sebaceous gland hyperplasia (43% of infants), which manifests as smaller, flatter, more yellow dots seen on the midface as well (Figure 102-3). Histologically, milia are keratogenous cysts similar to Epstein pearls, which are distributed along the midpalatal raphe. Bohn nodules are cysts that occur on the palate and the buccal and lingual aspects of the dental ridges and represent remnants of mucous gland tissue. Intraoral lesions are found in 75% to 80% of newborns. Because all these cysts exfoliate or involute spontaneously within the first few weeks of life, no treatment is required. The nevus simplex is the most common neonatal cutaneous lesion and is present in up to 80% of normal newborns (Figure 102-4).49 These lesions blanch when compressed and are usually centrally located and symmetric, appearing on the nape, the eyelids, and the glabella. In a prospective study of affected infants, most of the facial lesions had faded by 1 year of age, but those on the neck were more persistent. Surveys of adult populations confirm the persistence of the nuchal lesions in approximately one fourth of the population. Erythema toxicum is a benign and self-limited eruption that usually develops at 24 to 72 hours of age, but new lesions may appear until 2 to 3 weeks of age.70,76 The disorder is more common in term than premature infants, which suggests that it may represent an inflammatory reaction requiring mature skin. These lesions may vary considerably in character and number; they may be firm, 1- to 3-mm, pale yellow to white papules or pustules on an erythematous base resembling flea bites or erythematous macules as large as 3 cm in diameter. Individual lesions are evanescent, often lasting only a matter of hours. They may be found on any area of the body, but occur only rarely on the palms and soles. They are asymptomatic with no related systemic involvement and the cause is unknown, although a variety of specific cytokines have been implicated in the pathogenesis. A microscopic examination of a Wright- or Giemsa-stained smear of the pustule contents demonstrates numerous eosinophils; Gram stains are negative for bacteria and cultures are sterile. No treatment is necessary because spontaneous resolution occurs in 6 days to 2 weeks. Transient neonatal pustular melanosis is a distinctive eruption that consists of three types of lesions. First-stage lesions are small superficial vesiculopustules with little or no surrounding erythema.76 These rapidly progress to the second stage, which consists of collarettes of scale or scale crust surrounding a hyperpigmented macule (third stage) (Figure 102-5). All three types of lesions may be present at birth, but the macules are observed more frequently. The lesions may be profuse or sparse and occur on any body surface, including the palms, soles, and scalp. Sites of predilection are the forehead, submental area and anterior neck, and lower back. When intact pustules rupture, a pigmented macule often is discernible central to the collarette of scale, which represents the margin of the unroofed pustule. Presumably, the macules result from postinflammatory hyperpigmentation, and those present at birth may be the sequelae of in utero pustular lesions. Pustular melanosis may be confused with erythema toxicum, congenital cutaneous candidiasis, or staphylococcal pyoderma.76,92 Cultures and Gram stains of smears prepared from intact pustules are devoid of organisms; Wright stains of intralesional contents demonstrate cellular debris, polymorphonuclear leukocytes, and a few or no eosinophils, in contrast to those of erythema toxicum. Although the pustules disappear in 48 hours, the hyperpigmented macules may persist for as long as 3 months. Neither type of lesion requires therapy, and although the cause is unknown, parents may be reassured that the disorder is benign and transient. Miliaria is an eruption resulting from eccrine sweat duct obstruction leading to sweat retention.76 The three types of lesions are superficial thin-walled vesicles without inflammation (i.e., miliaria crystallina, Figure 102-6); small, erythematous, grouped papules (i.e., miliaria rubra); and nonerythematous pustules (i.e., miliaria pustulosis or profunda). The eruption most frequently develops in the intertriginous areas and over the face and scalp. It is exacerbated by exposure to a warm and humid environment. Miliaria sometimes can be confused with erythema toxicum; rapid resolution of the lesions when the infant is placed in a cooler environment differentiates them from pyoderma. A Wright-stained smear of vesicular lesions demonstrates only sparse squamous cells or lymphocytes, permitting exclusion of infectious vesicular eruptions. No topical therapy is indicated. Neonatal acne (i.e., neonatal cephalic pustulosis) is a relatively common condition that affects both sexes. It consists of small, red papules and pustules on the face during the first weeks of life. Comedones and cysts are usually absent. The lesions are asymptomatic and resolve spontaneously over several weeks. It has been suggested that occurrence of these lesions is coincident with colonization by the yeast Malassezia furfur.29 In contrast, infantile acne is an uncommon but distressing facial eruption (usually in male infants) that has its onset somewhat later, during the first few months of life.29,76 This condition resembles acne in the adolescent patient and is characterized by comedones, papules, pustules, and rarely, nodules. The duration may vary, but the disorder usually clears spontaneously during the latter portion of the first year of life. This condition may represent a heightened response of the sebaceous glands to neonatal androgens. No treatment or treatment with mild topical acne preparations to produce drying and peeling should suffice. Occasionally, the infant may be left with pitted scarring, and some may experience severe acne as adolescents. Infantile acropustulosis consists of pruritic papules and vesiculopustules with onset from birth to 10 months of age. The lesions appear in crops every 2 to 3 weeks and last 7 to 10 days. They involve the hands and feet primarily, but occasionally may involve the limbs as well. Because of the distribution, it is often confused with scabies. It is more common in African-American and male infants. The condition resolves spontaneously. A subcorneal pustule filled with neutrophils is seen on skin biopsy. Traditional therapy consists of topical steroids and antihistamines, although a recent report indicates successful treatment with topical maxacalcitol, an active form of vitamin D3.53 Recently, recessive mutation in the gene coding interleukin 1 receptor antagonist was described in a case of infantile pustulosis treated successfully with recombinant human interleukin 1 receptor antagonist anakinra.67 The most common causes of excessive scaling in the neonate are physiologic desquamation and dysmaturity, neither of which is of long-term significance. Less common causes include the congenital ichthyoses and the ectodermal dysplasias (particularly hypohidrotic ectodermal dysplasia), all of which are chronic, heritable disorders.18,46 TABLE 102-3 Clinical Presentation of Ichthyoses in the Newborn Adapted from Craiglow BG. Ichthyosis in the newborn. Semin Perinatol. 2013;37:26-31. The gestational age of a newborn with accentuated physiologic desquamation usually is 40 to 42 weeks; peak shedding occurs near the eighth day of life. These infants are otherwise normal in physical appearance and behavior. In contrast, the dysmature infant (see Chapter 23) has distinctive characteristics. The body is lean with thin extremities and decreased subcutaneous fat. The ponderal index is low with diminished body weight in relation to length. The skin is often scaly with parchment-like desquamation, especially of the distal extremities. There is often meconium staining of the skin as well as the nails and umbilical cord. The hair is abundant and the nails are abnormally long. In the normal infant with accentuated physiologic scaling and the dysmature infant, desquamation is a transient phenomenon, and the integument continues to serve its intended protective function. In contrast, the infant with congenital ichthyosis may have serious difficulties early in life because of impaired barrier function and the subsequent risks of secondary infection. The term ichthyosis derives from the similarity of the skin condition to the scales of a fish. It refers to a complex and often confusing plethora of conditions characterized by disorders of cornification with or without systemic symptoms.18,46 Ichthyosis in the newborn period may manifest as scaling only, scaling and erythroderma, a collodion membrane, or the thickened plates of harlequin ichthyosis. Although these conditions are relatively rare, it is important for the neonatal caregiver to recognize the patient with ichthyosis as the barrier function of the skin is often compromised. Prompt management and diagnosis can be lifesaving.95 Selected conditions with particular relevance to the newborn are highlighted below, followed by a general overview of treatment strategies. Table 102-3 lists the major clinical phenotypes of the ichthyoses in the newborn period. X-linked ichthyosis is the most common form of ichthyosis in the newborn period, affecting approximately 1 in 2500 male babies.95 Genetic mutations of the STS gene lead to deficiency of steroid sulfatase. Female carriers of the gene for X-linked ichthyosis, when pregnant with an affected male fetus, have a deficiency of placental steroid sulfatase reflected by low maternal urinary estriol excretion and a difficult or prolonged labor that often requires intervention. Clinical manifestations of X-linked ichthyosis in males include alterations in the skin, eye, and testes of affected infants. Most patients have cutaneous findings at birth, and 80% to 90% show scaling by 3 months of age. Rarely, a collodion membrane may be present. The hyperkeratosis is variable, but the scales typically are large, thick, and dark and are prominent over the scalp, neck, anterior trunk, and extensor extremities. Sparing of palms and soles and partial sparing of the flexures are helpful diagnostic features. Systemic manifestations are generally absent, and complications are rare. Skin biopsy is helpful (although the histologic pattern resembles that of lamellar ichthyosis), showing hyperkeratosis, a well-developed granular layer, hypertrophic epidermis, and a perivascular lymphocytic infiltrate. This form of ichthyosis is clinically apparent in affected homozygous males and not in heterozygous females. Because of the steroid sulfatase enzyme deficiency in the somatic tissues of affected males, increased levels of cholesterol sulfate can be documented by serum lipoprotein electrophoresis, and assays of steroid sulfatase activity show depressed levels of enzyme in cultured leukocytes, fibroblasts, amniocytes, and scales, confirming the diagnosis. Cryptorchidism is seen in approximately 25% of affected males; these patients may be at increased risk for testicular cancer. Deep stromal corneal opacities have also been found in about 50% of male infants with the disorder and in a smaller percentage of female carriers, but they do not affect vision. Management of ichthyotic patients in the newborn period runs the gamut from amelioration of mild cosmetic problems with excessive dryness and scaling to treatment of potentially life-threatening illness because of deficits in the epidermal barrier and subsequent infection. Table 102-4 lists the primary complications that form the primary targets of therapy for ichthyosis. Severely affected infants require aggressive topical care, liberal use of bland emollients, and careful monitoring of electrolyte needs. The infant should be placed in an environment with increased humidity and prompt attention paid to signs of infection. Often, the long-term goal of ichthyotic therapy is to eliminate scaling owing to excessive cornification and reduce dryness (xerosis) of the skin without inducing irritation. Keratolytic agents should be used with caution in the neonatal period and during the first 6 months of life, however. Although the stratum corneum is often thick and scaly, the barrier is compromised and there are significant risks of systemic absorption of potentially toxic substances such as lactic acid and salicylic acid. Avoidance of corneal desiccation and ulceration is critical if ectropion is present. TABLE 102-4 Clinical Complications of Ichthyosis and Therapeutic Management At present, there is no definitive cure for ichthyosis and current therapies are generally palliative. Over the past decade, however, the molecular basis of many of these predominantly monogenetic disorders have been elucidated.18,46 Identification of the affected genes opens the door for prenatal diagnosis and genetic counseling for these potentially lethal conditions. Unusual associations between skin and brain have recently been described, including a link between steroid sulfatase deficiency in X-linked ichthyosis and attention deficit hyperactivity disorder (ADHD). Rapid progress in this field is anticipated, including the possibility of cutaneous gene therapy.95 Parents are referred to an extensive online support group for families of infants with cornification disorders, the Foundation for Ichthyosis and Related Skin Types, FIRST (www.firstskinfoundation.org). Blistering eruptions in the neonatal period are relatively common (see Table 102-5) and may be caused by infections, congenital diseases, or infiltrative processes or may be of unknown origin.3,5,28,31 The proper management of such infants depends on knowledge of the cause of the disease or, when this is not possible, on an understanding of the pathogenesis of the type of blister encountered. Establishing the pathogenesis often depends on determining at which level within the skin the blister has occurred. TABLE 102-5 Clinical Conditions of the Newborn Presenting with Cutaneous Vesicles, Bullae, Pustules, and Erosions Adapted from Antaya RJ, Robinson DM. Blisters and pustules in the newborn. Pediatr Ann. 2010;39:635-645; Avram MM, Gobel V, Sepehr A. Case records of the Massachusetts General Hospital. Case 30-2007. A newborn girl with skin lesions. N Engl J Med. 2007;357:1327-1335. Bacterial sepsis in the neonate can present with vesicles, pustules, or bullae. The most common cause of sepsis presenting with pustules is S. aureus. Group B Streptococcus (GBS) agalactiae is a leading cause of neonatal sepsis, pneumonia, and meningitis, but it rarely manifests in the neonate at birth with vesicles, pustules, or bullae.55 In an attempt to decrease the frequency of GBS, maternal prophylaxis is recommended before delivery under certain conditions. Other occasional causes of pustules and sepsis in neonates include Listeria monocytogenes, Haemophilus influenzae, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Superficial skin infections caused by Staphylococcus aureus range from localized bullous impetigo to generalized cutaneous involvement with systemic illness. In contrast to congenital blistering diseases, which are often present at birth, skin infections with S. aureus usually develop after the first few days of life.44,90 They may be bullous, crusted, or pustular. Typical lesions are small vesicles or pustules or large, fragile bullae filled with clear, turbid, or purulent fluid. They rupture easily, leaving red, moist, denuded areas often with a superficial varnish-like crust. Although they may develop anywhere on the body, the blisters and pustules commonly occur on the diaper area, axillae, and periumbilical skin. The diagnosis is made by Gram stain and culture of the blister fluid, which can distinguish this eruption from streptococcal impetigo and other bullous disorders of the neonatal period. Blood cultures should be obtained from affected infants before initiating systemic antibiotic therapy, even if the infants are usually otherwise well. Contacts and nursery personnel should be investigated for a source of the infectious organism. The infant should be placed in isolation and observed carefully for early signs of sepsis. A high index of suspicion during examination of other infants in the nursery is the most effective means of preventing epidemic spread of this infection. The infecting organism in scalded skin syndrome is S. aureus, usually a group 2 phage type, although other phage types occasionally have been incriminated. These organisms produce an exotoxin (i.e., exfoliatin) that has proteolytic activity on desmoglein-1, a molecule found within the desmosomes of keratinocytes that is responsible for the cutaneous manifestations.58,90 Two major serotypes of the toxin, A and B, cause bullous impetigo and scalded skin syndrome. In cases of the former, the toxin produces exfoliation and blisters locally, whereas in the latter, the toxin circulates systemically with widespread epidermal necrolysis. Histologic examination of the skin demonstrates separation at the level of the granular layer with cell death and acantholysis; there is a striking absence of inflammatory infiltrate. Because intact bullae are sterile, cultures should be obtained from the nasopharynx, conjunctival sac, umbilicus, abnormal skin, blood, urine, and any other suspected focus of infection that might have provided a portal of entry for the organism. Treatment consists of prompt systemic administration of penicillinase-resistant semisynthetic penicillin and pain management. Fluid and electrolyte replacement is warranted if necessary, and recent reports indicate successful use of skin-substitute dressings.6 Flaky desquamation occurs during the healing phase. Scarring never occurs because the blister cleavage plane is intraepidermal.
The Skin of the Neonate
The Structural Biology of Fetal and Neonatal Skin
Development of the Epidermis
Development of the Appendages
Vernix Biology
Development of the Dermis
Blood and Lymphatic Vessel Development
Development of Cutaneous Innervation
Disorders and Diseases of Fetal and Neonatal Skin
Type
Description
Clinical Examples
Macule
A circumscribed, flat lesion with color change, up to 1 cm in size; by definition, they are not palpable
Ash leaf macules, café-au-lait spots, capillary ectasias
Patch
Same as macule but >1 cm in size
Nevus depigmentosus, nevus simplex, mongolian spots
Papule
A circumscribed, elevated, solid lesion, up to 1 cm in size; elevation may be accentuated with oblique lighting
Verrucae, milia, juvenile xanthogranuloma
Plaque
A circumscribed, elevated, plateau-like, solid lesion, >1 cm in size
Mastocytoma, nevus sebaceous
Nodule
A circumscribed, elevated, solid lesion with depth, up to 2 cm in size
Dermoid cysts, neuroblastoma
Tumor
Same as a nodule but >2 cm in size
Hemangioma, lipoma, rhabdomyosarcoma
Vesicle
A circumscribed, elevated, fluid-filled lesion up to 1 cm in size
Herpes simplex, varicella, miliaria crystalline
Bulla
Same as a vesicle but >1 cm in size
Sucking blisters, epidermolysis bullosa, bullous impetigo
Wheal
A circumscribed, elevated, edematous, often evanescent lesion, caused by accumulation of fluid within the dermis
Urticaria, bite reactions, drug eruptions
Pustule
A circumscribed, elevated lesion filled within purulent fluid, <1 cm in size
Neonatal pustular melanosis, erythema toxicum neonatorum, infantile acropustulosis
Abscess
Same as a pustule but >1 cm in size
Pyodermas
Type
Description
Clinical Examples
Crust
Results from dried exudates overlying an impaired epidermis. Can be composed of serum, blood, or pus.
Epidermolysis bullosa, impetigo
Scale
Results from increased shedding or accumulation of stratum corneum as a result of abnormal keratinization and exfoliation. Can be subdivided further into pityriasiform (branny, delicate), psoriasiform (thick, white, and adherent), and ichthyosiform (fish scale–like).
Ichthyoses, postmaturity desquamation, seborrheic dermatitis
Erosion
Intraepithelial loss of epidermis. Heals without scarring.
Herpes simplex, certain types of epidermolysis bullosa
Ulcer
Full thickness loss of the epidermis with damage into the dermis. Will heal with scarring.
Ulcerated hemangiomas, aplasia cutis congenita
Fissure
Linear, often painful break within the skin surface, as a result of excessive xerosis.
Inherited keratodermas, hand and foot eczema
Lichenification
Thickening of the epidermis with exaggeration of normal skin markings caused by chronic scratching or rubbing.
Sucking callus, atopic dermatitis
Atrophy
Localized diminution of skin. Epidermal atrophy results in a translucent epidermis with increased wrinkling, whereas dermal atrophy results in depression of the skin with retained skin markings. Use of topical steroids can result in epidermal atrophy, whereas intralesional steroids may result in dermal atrophy.
Aplasia cutis congenita, intrauterine scarring, and focal dermal hypoplasia
Scar
Permanent fibrotic skin changes that develop as a consequence of tissue injury. In utero scarring can occur as a result of certain infections or amniocentesis or postnatally from a variety of external factors.
Congenital varicella, aplasia cutis congenita
Transient Cutaneous Lesions
Sebaceous Gland Hyperplasia and Milia
Nevus Simplex or Salmon Patch65
Erythema Toxicum
Transient Neonatal Pustular Melanosis
Miliaria
Neonatal Acne and Infantile Acne
Infantile Acropustulosis
Disorders of Cornification: The Scaly Baby
Phenotype
Type of Ichthyosis
Erythroderma
Netherton syndrome, KID syndrome, CIE
Also consider: Omenn syndrome, SCID, ectodermal dysplasia, erythrodermic psoriasis
Generalized scaling
XLI, Netherton syndrome, Sjögren-Larsson syndrome, trichothiodystrophy, neutral lipid storage disease
Collodion baby
Lamellar ichthyosis, CIE, self-healing collodion baby, harlequin ichthyosis (mild), Sjögren-Larsson syndrome, trichothiodystrophy, neutral lipid storage disease
Also consider: ectodermal dysplasias, Gaucher disease
Vernix-like hyperkeratosis
Harlequin ichthyosis, KID syndrome
Constrictive scales with deformities
Harlequin ichthyosis
Blisters/erosions
Epidermolytic ichthyosis, ichthyosis bullosa of Siemens
Also consider: epidermolysis bullosa, TEN, SSSS, immunobullous disease, mastocytosis
Physiologic Desquamation and Dysmaturity
Ichthyoses
X-Linked Ichthyosis.
Management of Ichthyosis.
Complications with Ichthyosis
Therapeutic Management Strategies
Restricted chest movement, contractures of limbs and soft tissues, sucking and feeding problems, compartment syndromes
Respiratory support, nasogastric feeding, liberal emollients with daily bathing and/or retinoids to thin and remove scale, monitor tissue perfusion and compartment pressure, orthopedic and plastic surgery evaluation of contractures, ophthalmology consult for ectropion and avoidance of corneal desiccation
Risk for bacterial infections and sepsis caused by impaired epidermal barrier
Watch for clinical signs of localized infection and/or sepsis with institution of aggressive culturing and treatment, topical antibiotics to fissures, reverse isolation
Risk of dehydration and electrolyte imbalance
Monitor fluid balance and electrolytes, humidified incubator to decrease evaporative water loss, intravenous hydration and/or alimentation
Fragile, easily traumatized skin; risk of absorption of topical preparations
Minimal handling, avoid aggressive adhesives, use self-adherent wraps or gauze, use bland emollients, avoid silver sulfadiazine, lactic acid and salicylic acid preparations, antibacterial soaps
Future Prospects.
Vesicobullous Eruptions
Differential Category
Specific Conditions
Noninfectious transient conditions
Sucking blister, superficial trauma, miliaria, neonatal acne, erythema toxicum neonatorum, transient neonatal pustular melanosis, eosinophilic pustular folliculitis, acropustulosis of infancy
Nontransient bullous dermatoses
Epidermolysis bullosa, Langerhans-cell histiocytosis, incontinentia pigmenti, epidermolytic hyperkeratosis, pemphigus vulgaris, mastocytosis, hyper-IgE syndrome, herpes gestationis
Infectious vesiculopustular dermatoses
Viral infections: Herpes simplex, varicella, cytomegalovirus;
Bacterial infection: Group B streptococcus, Group A streptococcus, Haemophilus influenza type B, Staphylococcus aureus, Listeria, Pseudomonas;
Other: Treponema pallidum, scabies, Candida, Aspergillus
Sepsis
Staphylococcal Infection and Impetigo
Staphylococcal Scalded Skin Syndrome
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The Skin of the Neonate
