I. Evaluation and Clinical Descriptions of Skin Findings

A. Primary Skin Lesions

1. 1. Macule: Small, flat, well-circumscribed discolored lesion (<1 cm)
2. 2. Patch: Large macule (≥1 cm)
3. 3. Papule: Small, elevated, firm, well-circumscribed superficial lesion (<1 cm)
4. 4. Plaque: Large papule (≥1 cm)
5. 5. Pustule: Small, well-circumscribed elevation of skin containing purulent material (<1 cm)
6. 6. Vesicle: Small, well-circumscribed elevation of skin containing serous fluid (<1 cm)
7. 7. Bulla: Large vesicle (≥1 cm)
8. 8. Wheal: Transient, raised, well-circumscribed lesion with erythematous periphery and central pallor
9. 9. Nodule: Soft or firm lesion in dermis or subcutaneous fat (≥1 cm)
10. 10. Tumor/mass: Solid, firm lesion (typically ≥2 cm)

B. Secondary Skin Lesions

1. 1. Scale: Small, thin plates (scales) shedding from the surface of the skin
2. 2. Crust: Solidified exudative material from erosions or ruptured vesicles/pustules
3. 3. Erosion: Loss of the most superficial layers of the epidermis from friction, pressure, or inflammation that heals without scarring
4. 4. Ulcer: Full-thickness loss of the epidermis and at least a part of the dermis, with clearly defined edges, that heals with scarring
5. 5. Fissure: Linear or wedge-shaped epidermal tear that reaches into the dermis and may be associated with inflammation and pain
6. 6. Excoriation: Any loss of substance of the skin secondary to scratching
7. 7. Lichenification: Thickening of the epidermis with accentuated skin lines, secondary to chronic inflammation and/or scratching
8. 8. Scar: Formation of new connective tissue after full-thickness injury to skin, leaving permanent change in skin

C. Shapes and Arrangements

1. 1. Linear: Distributed along a line
2. 2. Dermatomal: Following a dermatome
3. 3. Filiform: Thread-like
4. 4. Serpiginous: Wavy, coiled, serpentine pattern
5. 5. Annular: Ring-like configuration
6. 6. Nummular/discoid: Disk-like, coin-shaped lesion
7. 7. Targetoid: Resembling a bull’s-eye target with central erythema surrounded by pale edema with a peripheral border of erythema
8. 8. Clustered: Lesions in a group
9. 9. Herpetiform: Clustered vesicular lesions on erythematous bases (herpes simplex pattern)
10. 10. Reticulated: Net or lacey distribution
11. 11. Geographic: Resembling outlines on a map such as a continent
12. 12. Morbilliform: Eruption of erythematous to dusky coalescing macules with interspersed healthy skin

II. Vascular Anomalies

Section references: 1

A. Vascular Tumors

1. 1. Infantile hemangiomas (Fig. 8.1, Color Plates)^2,3
   1. a. Pathogenesis: Benign vascular tumor with rapid proliferation followed by spontaneous involution. Most present before 4 weeks of age. Undergo rapid growth between 1 and 2 months of age, with 80% of size reached by 3 months. Most begin to regress between 6 and 12 months of age, with the majority of tumor regression occurring by 4 years of age. 50% to 70% resolve completely.
   2. b. Clinical presentation: Newborns may demonstrate pale macules with overlying or surrounding, thread-like telangiectasias that later develop into hemangiomas. May be superficial, deep, or mixed. Pattern may be focal (neat round lesions) or segmental (following embryologic segments). After involution, can have residual skin changes including scarring and atrophy
   3. c. Indicators that should prompt consideration for early treatment:
      1. (1) Potential for life-threatening complications: Airway hemangiomas, liver hemangiomas (associated with high-output heart failure and severe hypothyroidism), and profuse bleeding from an ulcerated hemangioma
      2. (2) Risk of functional impairment: Interference with the development of vision (if near eye) and interference with feeding (if near mouth)
      3. (3) Ulceration: Most common complication (5% to 21%). Can be extremely painful and usually scars; risk greatest in large hemangiomas and those located in skin creases, particularly the diaper area
      4. (4) Associated structural anomalies: PHACES syndrome ( Posterior cranial fossa malformations, large segmental facial Hemangiomas, Arterial lesions, Cardiovascular anomalies [aortic anomalies], Eye anomalies, Sternal cleft anomalies/supraumbilical raphes⁴) and LUMBAR syndrome ( Lower body hemangioma, Urogenital anomalies, Ulceration, Myelopathy, Bony deformities, Anorectal malformations, Arterial anomalies, Renal anomalies)
      5. (5) Potential for disfigurement: Risk of permanent scarring or distortion of anatomic landmarks
   4. d. Diagnosis: Usually diagnosed clinically. Atypical clinical findings, growth pattern, and equivocal imaging should prompt tissue biopsy to exclude other neoplasms or unusual vascular malformations. See Table 8.1 for indications to order imaging.
      • (1) Consult the free International Society Study of Vascular Anomalies (ISSVA) classification online for characterization and differentiation between benign and aggressive vascular tumors
   5. e. Treatment:
      1. (1) Most are uncomplicated and can be observed with watchful waiting. Photo documentation is used to follow the growth and regression process.
      2. (2) If an infantile hemangioma is identified as high risk, the child should be evaluated by a hemangioma specialist promptly, as there is a narrow window of opportunity in which to intervene and prevent poor outcomes.
      3. (3) β-adrenergic blockers such as propranolol are considered first-line therapy for complicated infantile hemangiomas and should be initiated under supervision of a pediatric dermatologist or experienced practitioner.⁵ While patients should be clinically screened for cardiac disease, EKG and/or echocardiogram are not required unless there is clinical concern. Contraindications include: reactive airways, sinus bradycardia, decompensated heart failure, greater than first-degree heart block, hypotension, hypoglycemia, hypersensitivity to propranolol. Off-label use of selective β-blockers may be considered in certain patients. Duration should be at least 6 months and up to 12 months of age.⁶
      4. (4) Corticosteroids are considered second line. Similar efficacy to propranolol in a prospective, randomized, investigator-blinded trial, but propranolol is better tolerated and with fewer severe side effects.⁷
      5. (5) Topical timolol is effective in superficial, uncomplicated hemangiomas (recommend 0.5% gel forming solution).
      6. (6) Ulcerated hemangiomas may respond to pulsed dye laser therapy or topical or systemic steroids.
2. 2. Pyogenic granuloma (lobular capillary hemangioma) (Fig. 8.2, Color Plates)
   1. a. Clinical presentation: Benign vascular tumor, appears as small (usually 3 to 10 mm but occasionally much larger), bright red papule that grows over several weeks to months into sessile or pedunculated papule with a “collarette,” scale, or crust. Can bleed profusely with minor trauma and can ulcerate. Rarely spontaneously regresses. Seen in all ages; average age of diagnosis 6 months to 10 years. Located on head and neck, sometimes in oral mucosa but can be at any skin site and often misdiagnosed as hemangiomas
   2. b. Treatment: Usually required, given frequent bleeding and ulceration. Options include shave excision or curettage with cautery of base, surgical excision, carbon dioxide laser excision, or pulsed dye laser therapy. For most cases, shave and cautery are quick, safe, low risk, and can be performed quickly with local anesthesia. Small, intact lesions may respond to topical timolol therapy.

B. Vascular Malformations
Include capillary (port-wine stains and salmon patch/stork bite/angel kiss), lymphatic, venous, and arteriovenous malformations
NOTE: For a comparison of vascular malformations to vascular tumors, please see eTable 8.1.⁸

III. Infections

A. Viral

1. 1. Warts
   1. a. Pathogenesis: Human papillomaviruses (HPVs) of the epithelium or mucus membrane
   2. b. Clinical presentation:
      1. (1) Common warts: Skin-colored, rough, minimally scaly papules and nodules found most commonly on the hands, although can occur anywhere. Can be solitary or multiple, range from a few millimeters to several centimeters, may form large plaques or a confluent linear pattern secondary to autoinoculation. Sometimes persistent in immunocompromised patients and persistence may be a marker for underlying immunodeficiency.
      2. (2) Flat warts: Flesh to brown/yellow-colored, smooth, flat-topped papules commonly found over the hands, arms, and face. Usually <2 mm in diameter and often present in clusters
      3. (3) Plantar warts: Occur on soles of feet as inward-growing, hyperkeratotic plaques and papules. Trauma on weight-bearing surfaces results in small black dots (petechiae from thrombosed vessels on the surface of the wart). Can be painful
   3. c. Diagnosis: Clinical diagnosis; using a magnifier may help confirm clinical diagnosis
   4. d. Treatment⁹:
      1. (1) Spontaneous resolution occurs in greater than 75% of warts in otherwise healthy individuals within 3 years. No specific treatment clearly better than placebo, except possibly topical salicylic acid. Cryotherapy is sometimes combined with salicylic acid, but the efficacy of this combination has not been proven.
      2. (2) Keratolytics (topical salicylates): Particularly effective in combination with adhesive tape occlusion. Response may take 4 to 6 months.
      3. (3) Intralesional bleomycin, topical or intralesional fluorouracil, laser therapy, topical sensitizers, and imiquimod have been used for refractory warts, but the efficacy has not been proven. Destructive techniques, Candida antigen, cantharidin, or “beetle juice” are not clearly more effective than placebo. Additionally, destructive techniques can be painful and cause scarring, particularly on the digits. These options are not routinely recommended in children.
2. 2. Molluscum contagiosum (Fig. 8.3, Color Plates)
   1. a. Pathogenesis: Large DNA poxvirus. Spread by skin-to-skin contact
   2. b. Clinical presentation: Dome-shaped, often umbilicated, translucent to white papules that range from 1 mm to 1 cm. Occur anywhere but only rarely on palms and soles, most commonly on the trunk and intertriginous areas. Can occur in the genital area and lower abdomen when obtained as a sexually transmitted infection in sexually active adolescents and autoinoculation in younger children. May be pruritic and can be surrounded by erythema, resembling eczema. The surrounding red, scaly reaction is referred to as “the beginning of the end” (see Treatment).
   3. c. Diagnosis: Clinical diagnosis; magnifier can be used to distinguish from warts and other papular lesions
   4. d. Treatment: Most spontaneously resolve within 6 to 18 months and do not require intervention other than monitoring for secondary bacterial infection. Surrounding eczematous changes may indicate an immunologic reaction and serve as a harbinger of regression. Treatment may cause scarring and may not be more effective than placebo. For symptomatic lesions curettage, topical irritants and sensitizers, and cantharidin may be an option. Recurrences are common.
3. 3. Herpes simplex virus
   1. a. Pathogenesis: Either HSV-1 or HSV-2 may be implicated, regardless of lesion location. During the initial outbreak, oral lesions last 2 to 3 weeks, whereas genital lesions may last 2 to 6 weeks. Recurrent episodes are usually much shorter.
   2. b. Clinical presentation ( Fig. 8.5 , Color Plates): Symptoms include prodrome of tingling, itching, or burning followed by painful vesicles on erythematous base that may last 7 to 10 days, break open, and crust prior to healing; flu-like symptoms; dehydration (gingivostomatitis); dysuria (genital); ophthalmologic symptoms (keratitis). May be triggered by stress, illness, sun exposure, and menstruation. The first outbreak is typically the worst.
   3. c. Intrauterine HSV skin findings: Recent case series show that cutaneous manifestation of HSV acquired in utero includes erosions, ulcerations, crusted papules or plaques, calcinosis cutis, excoriations, macules (erythematous, scaring with hypopigmented or hyperpigmented lesions), cutaneous atrophy, contractures, and bruising in addition to vesicles with erythematous base.
   4. d. Diagnosis: Diagnosed clinically and, in many centers, with viral DNA PCR (more sensitive than culture). To culture a lesion, clean with alcohol, un-roof lesion with sterile needle or wooden side of cotton swab, collect vesicular fluid on sterile swab, and send in viral transport medium.
   5. e. Treatment: Acyclovir or valacyclovir for 7 to 14 days (see Formulary for dosing). For children with herpetic gingivostomatitis, antiviral therapy should be initiated within 72 to 96 hours of onset if they are unable to drink or have significant pain. Valacyclovir is generally preferred as it is more bioavailable than acyclovir and, as a result, is dosed less frequently. See infectious disease chapter for more details on neonatal HSV.
4. 4. Erythema infectiosum (“fifth disease”)
   1. a. Pathogenesis: Parvovirus B19
   2. b. Clinical presentation: Pediatric presentation of nonspecific febrile illness with headache, coryza, and gastrointestinal complaints. Two to five days after onset of symptoms, the classic malar rash with “slapped cheek” appearance erupts, followed by a reticular rash to the trunk several days later. Associated signs and symptoms include arthralgias (more common in adults) and a transient aplastic crisis, which may be more of a problem in patients with hemoglobinopathies and pregnant women.
   3. c. Diagnosis: Clinical diagnosis, serum IgM, or serum DNA PCR
   4. d. Treatment: Supportive care. Avoid people who are pregnant as virus can cause hydrops fetalis.
5. 5. Pityriasis rosea (PR, Figs. 8.9 and 8.10, Color Plates)
   1. a. Pathogenesis: Possible viral etiology (HHV-6, -7) as some cases are preceded by a prodrome of headache and malaise. No association with bacterial or fungal organisms has been found.
   2. b. Clinical presentation: Classically presents with a “herald” patch, a single salmon-colored oval patch 2 to 5 cm in diameter, with central clearing. In the following days, similar but smaller oval patches appear, usually on the trunk and proximal extremities. On the back, the confluence of patches may appear in a “Christmas tree” pattern. The rash usually spreads from top down or centrifugally. In young children, lesions more often involve the scalp, face, and groin and can spare the trunk. Symptoms resolve in 4 weeks to several months.
   3. c. Diagnosis: Clinical diagnosis, but KOH scrapings to differentiate from tinea may be necessary. In sexually active patients, testing is recommended to rule out secondary syphilis, which may mimic the rash of PR.
   4. d. Treatment: Will self-resolve without treatment. Symptomatic therapy with topical medium-potency steroids may reduce pruritis.
6. 6. Roseola infantum (Fig. 8.11, Color Plates)
   1. a. Pathogenesis: Human herpesvirus 6 (HHV-6, less commonly HHV-7)
   2. b. Clinical presentation: Typically diagnosed in children <2 years old with peak 7 to 13 months. Febrile phase of 3 to 5 days of high fever (often >40°C), viremia, and irritability. As febrile phase resolves, patients develop a morbilliform rash on neck and trunk that spreads centripetally to face and extremities for 1 to 2 days.
   3. c. Diagnosis: Clinical diagnosis
   4. d. Treatment: Self-resolving
7. 7. Hand, foot, and mouth disease
   1. a. Pathogenesis: Most commonly coxsackievirus A serotypes
   2. b. Clinical presentation: Oral lesions on the tongue, buccal mucosa, and palate that initially are 1- to 5-mm erythematous macules and evolve to vesicles and ulcers with a thin erythematous halo. Erythematous, nonpruritic 1- to 10-mm macules, papules, and/or vesicles on the palms and soles. Typically resolve in 3 to 4 days. Usually nontender, unless caused by coxsackie A6 (may be associated with high fevers, widespread lesions, longer duration [12 days], palmar and plantar desquamation, and nail dystrophy)
   3. c. Diagnosis: Clinical diagnosis. Most infections are now caused by coxsackie A6, and the rash tends to be worse in areas with normal skin trauma (face, extremities, diaper area). Moreover, lesions may be dramatic in areas with irritated skin such as in patches of eczema.
   4. d. Treatment: Supportive care
8. 8. Reactive erythema (Fig. 8.4; Figs. 8.5 to 8.11, Color Plates)
   1. a. Pathogenesis: Represent cutaneous reaction patterns triggered by endogenous and environmental factors (e.g., viral infections, drug reactions, immunizations)
   2. b. Clinical presentation: Group of disorders characterized by erythematous patches, plaques, and nodules that vary in size, shape, and distribution and may develop purpura, urticarial plaques, and erythema multiforme-like lesions

1. 1. Scabies (Figs. 8.12 to 8.14, Color Plates)
   1. a. Pathogenesis: Caused by the mite Sarcoptes scabiei. Spread by skin-to-skin contact and through fomites. Can live for 2 days away from a human host. Female mites burrow and lay eggs under the skin.
   2. b. Clinical presentation: Initial lesion is a small, erythematous papule that is easy to overlook. Can have burrows (elongated, edematous papulovesicles, often with a pustule at the advancing border) that are pathognomonic. Most commonly located in interdigital webs, wrist folds, elbows, axilla, genitals, buttocks, and belt line but can become widely disseminated. In temperate climates, the face and scalp are usually spared. In young infants, the palms and soles are also commonly involved. Burrows are most dramatic in patients who are unable to scratch (e.g., infants). An immunologically mediated disseminated eczematous (Id) eruption results in generalized severe pruritus, especially at night. Can become nodular, particularly in intertriginous areas, or be susceptible to superinfection due to frequent excoriations. Immunosuppressed patients may develop diffuse, scaly, crusted eruption and lack pruritus and may progress to “crusted scabies” or infection with very high numbers of mites, requiring more intensive topical and oral therapy.
   3. c. Treatment¹⁰:
      1. (1) Permethrin cream: 5% cream applied to skin from neck down in normal hosts, including under fingernails and toenails. Rinse off after 8 to 14 hours. Can repeat in 7 to 10 days
      2. (2) Ivermectin (off-label use): Single 200 mCg/kg dose; can repeat in 2 weeks. Efficacy comparable to permethrin cream. May be the best choice for immunodeficient patients for whom total body application may be difficult but is not considered first line for pregnant patients or children weighing less than 15 kg
      3. (3) Spinosad: 0.9% topical suspension, approved for treatment of scabies in adults and children 4 years of age and older. This treatment was approved in 2021, and its efficacy compared to prior treatments has not been well established.
      4. (4) Environment: Mites cannot live away from human skin for more than 2 to 3 days. Launder clothing and sheets. Bag and seal stuffed animals and pillows for 2 to 3 days. Consider treatment of close contacts.
2. 2. Head lice: Pediculosis capitis
   1. a. Pathogenesis: Caused by Pediculus humanus capitis. Female louse lays eggs (nits) on the base of the hair shaft, which hatch into nymphs that mature to adult lice in 1 week. Transmission occurs through direct contact with the head of a person with lice, and transmission through towels, brushes, or hats is controversial. Lice do not fly or jump.
   2. b. Clinical diagnosis: Should be suspected in child with scalp pruritus or persistent pyoderma around hairline. Diagnosis is confirmed by visualization of live lice, best done by using a fine-toothed nit comb through wet hair.
   3. c. Treatment: First-line treatment is topical pediculicides (permethrin, topical ivermectin, malathion, benzyl alcohol, topical dimethicone). Wet combing with a fine-toothed nit comb is an alternative for infants or patients who prefer to avoid medication. There is concern that lice are becoming resistant to topical permethrin and malathion; however, the most common cause of persistent head lice is poor adherence to treatment and continued exposure to other infected individuals. If resistance, independent from reinfection, is suspected, then oral ivermectin can be used.

C. Fungal (Figs. 8.15 to 8.19, Color Plates)

1. 1. Tinea capitis (Fig. 8.15, Color Plates)
   1. a. Pathogenesis: Mostly caused by fungi of the genus Trichophyton in North America (95%), less commonly Microsporum (5% or less), and spread through direct contact and fomites
   2. b. Epidemiology: Usually occurs in young children, with higher incidence in type 4 hair follicles
   3. c. Clinical presentation:
      1. (1) Black dot: Most common. Slowly growing, minimally scaly patches, sometimes erythematous but often with little or no inflammation until later in the course. These areas develop alopecia, and black dots are visible on scalp where hair has broken.
      2. (2) Gray patch (“seborrheic dermatitis type”): Erythematous, scaling, well-demarcated patches that grow centrifugally. Hair breaks off a few millimeters above the scalp and takes on a gray/frosted appearance.
      3. (3) Kerion (Fig. 8.16, Color Plates): Complication of tinea capitis or tinea corporis. Type IV hypersensitivity to fungus. Raised, boggy/spongy lesions, often tender and covered with purulent exudate. Most commonly occurs months after primary infection
      4. (4) All can be associated with posterior cervical lymphadenopathy.
      5. (5) Secondary infection usually from Staphylococcus aureus may be associated with tender pustules requiring treatment with oral antibiotic.
   4. c. Diagnosis: Can be made clinically, but since oral antifungal therapy is indicated, tinea capitis should be confirmed by direct microscopic exam of a potassium hydroxide (KOH) preparation of the proximal ends of hairs, gently and painlessly scraped from the affected area. Cultures should be obtained on all patients by using a sterile toothbrush or cotton swab. The scale can be scraped directly into a sterile plastic cup and/or the cotton swab tips can be broken off and placed into the sterile plastic cups.
   5. d. Treatment ¹¹ : (Intent for Clinical Review submitted by Section of Dermatology (SOD) of American Academy of Pediatrics (AAP)) Always requires systemic therapy. First-line therapy includes oral griseofulvin for 10 to 12 weeks (which should be taken with fatty foods for improved absorption) or terbinafine for 6 weeks (see Formulary for dosing). Most experts consider terbinafine superior to griseofulvin for T. tonsurans because of its shorter duration of therapy and superior effectiveness. The FDA recommends baseline and follow-up hepatic function testing in children taking terbinafine, though most clinicians forego laboratory testing in healthy children without history of liver disease if treatment is 6 weeks or less. Though not FDA approved for tinea capitis, fluconazole at 6 mg/kg/day (max 400 mg/day) for 6 weeks is recommended by the AAP Red Book as an alternative treatment of tinea capitis in children younger than 2 years old.¹² All family members, particularly other children, should be examined carefully for subtle infection. Selenium sulfide 2.5% shampoo may shorten the period of shedding of fungal organisms and reduce risk of infection of unaffected family members. Off-label treatment with itraconazole 5 to 6 mg/kg/day for 6 weeks (comes in liquid formulation as well, which makes it easier to use in infants and toddlers). For kerion, can use high-potency topical steroid for 1 to 2 weeks at same time that start oral therapy but if severe maybe 1 to 2 weeks of oral steroid; treat secondary bacterial infection with 1 to 2 weeks of oral antibiotic.
2. 2. Tinea corporis and pedis¹¹ (Figs. 8.17 and 8.18, Color Plates)
   1. a. Pathogenesis: Spread through direct contact and fomites, especially in sports with close contact (e.g., tinea gladiatorum)
   2. b. Clinical presentation: Pruritic, erythematous, annular patch or plaque with central clearing and a scaly raised border. Typically affects hair-free skin, but any skin can be affected
   3. c. Diagnosis: Usually diagnosed clinically, but a KOH preparation or fungal culture can be used to help guide diagnosis and treatment. If widespread and considering oral therapy, send fungal culture to confirm diagnosis.
   4. d. Treatment: Topical antifungals (terbinafine, miconazole, clotrimazole, ketoconazole) through 1 to 2 weeks past lesion resolution. Widespread eruption may require oral antifungals.
3. 3. Tinea (pityriasis) versicolor (Fig. 8.19, Color Plates)
   1. a. Pathogenesis: Caused by Malassezia. Exacerbated by hot/humid weather, hyperhidrosis, topical skin oil use. Most people are colonized with Malassezia, but only a small number are prone to develop clinical lesions. Not associated with poor hygiene. Not contagious
   2. b. Clinical presentation: Well-demarcated, minimally scaly, hypopigmented macules or patches. Hypopigmented areas tend to be more prominent in the summer because affected areas do not tan. Lesions often have a fine scale that may be noted following gentle rubbing and can be mildly pruritic but are usually asymptomatic.
   3. c. Diagnosis: KOH microscopy reveals pseudohyphae and yeast cells that appear like “spaghetti and meatballs.”
   4. d. Treatment: Topical antifungal shampoos and/or creams (miconazole, oxiconazole, ketoconazole) or selenium sulfide are effective. Given the risk of hepatotoxicity, oral azole antifungals are reserved for resistant or widespread disease. Oral terbinafine is not effective. Pigmentation changes may take months to resolve despite successful treatment.
4. 4. Id reaction
   1. a. Pathogenesis: Possible delayed-type hypersensitivity response to fungal antigens, also referred to as “autoeczematization” or “dermatophytid reaction”
   2. b. Clinical presentation: A new onset pruritic, papular, vesicular rash in a patient with tinea pedis, tinea manuum, tinea cruris, tinea corporis, or tinea capitis. Typically occurs after treatment of the dermatophyte has been initiated. Often presents as patient or caregiver concern for allergy to the antifungal treatment
   3. c. Diagnosis: Clinical
   4. d. Treatment: Continue treatment for underlying dermatophyte. Topical corticosteroids or other antipruritic treatment may be used.

D. Bacterial

1. 1. Impetigo
   1. a. Pathogenesis: Contagious bacterial infection of the skin, most commonly caused by Staphylococcus aureus (99% MSSA), with a minority of cases caused by Group A Streptococcus
   2. b. Clinical presentation:
      1. (1) Nonbullous impetigo: Papules that evolve into erythematous pustules or vesicles that break and form thick, honey-colored crusts and plaques. Commonly overlying any break to skin barrier. Primarily face and extremities
      2. (2) Bullous impetigo: Painless vesicles that evolve into flaccid bullae and crusted patches with undermined border. Seen more in infants and young children. Caused by Staphylococcus aureus exfoliative toxin A
   3. c. Diagnosis: Clinical diagnosis
   4. d. Treatment: When impetigo is contained to a small area, topical mupirocin may be used for 5 days. When the infection is widespread, an oral antibiotic such as cephalexin should be used for 7 days. Consider broader coverage if MRSA is suspected, although MSSA accounts for most infections.
2. 2. Staph scalded skin syndrome
   1. a. Pathogenesis: Staphylococcus aureus infections of the skin with hematogenous dissemination of exfoliative toxin A or B to the epidermis
   2. b. Clinical presentation: Typical presentation is Ritter disease (generalized exfoliation) in a 3- to 7-day-old infant who initially is febrile and irritable with conjunctivitis and perioral erythema. In addition to newborns, this presentation is seen in young children who do not have antibodies to the toxin and often do not clear the toxin-antibody complex quickly due to decreased renal excretion. It many also occur in older children and adults with renal failure who cannot clear the toxin/antibody complex. One to two days after the prodromal onset, patient develops diffuse erythema, fragile, flaccid bullae, and erosions that are Nikolsky positive (mild rubbing of skin causes skin to slough off) in areas of mechanical stress such as intertriginous areas. Lesions are not scarring as they are intraepidermal. Older children tend to have a localized bullous impetigo with tender scarlatiniform eruption. Infants and toddlers usually have a combination of the presentations seen in neonates and older children followed 7 to 10 days later by white to brown thick flaking and desquamation of the entire body, especially hands, feet, face, and neck.
   3. c. Diagnosis: Typically clinically. However, cultures should be obtained from any potential source site of infection, if there is a primary site of infection. If there is no primary site of infection, look for sites of colonization such as the medial canthi, nares, or umbilical stump in newborns.
   4. d. Treatment: Nearly all cases are MSSA, with an increasing number being clindamycin resistant. First-line treatment may include oral penicillinase-resistant beta-lactams such as first- or second-generation cephalosporins. Vancomycin should be considered in patients who fail to respond to treatment and/or in areas with a high prevalence of MRSA. Management should also include supportive care with topical emollients and close monitoring of fluid and electrolyte status.
3. 3. Scarlet fever (Fig. 8.20, Color Plates)
   1. a. Pathogenesis: Exotoxin-mediated response to a Streptococcus pyogenes infection, typically pharyngitis
   2. b. Clinical presentation: Sandpaper-like, coarse, erythematous, blanching rash that originates in the groin and axilla, then spreads to the trunk, then extremities but spares the palms and soles. May have Pastia lines (pink/red lines in skin creases). Associated with pharyngitis, circumoral pallor, and a strawberry tongue
   3. c. Diagnosis: Clinical diagnosis. May benefit from rapid strep test and throat culture
   4. d. Treatment: No additional treatment aside from treating the patient’s Strep pharyngitis. Failing to correctly diagnose and treat increases risk of patient developing rheumatic fever.
4. 4. Cellulitis: See Chapter 17.

IV. Hair Loss

A. Telogen Effluvium

1. 1. Pathogenesis: Most common cause of diffuse hair loss. Telogen is the resting phase of hair growth that typically lasts 3 months, followed by hair shedding. Normally, 10% of hairs are in resting phase. Acute events (such as infection, fever, anesthesia, certain medications) can trigger premature telogen that results in a larger number of hairs shed 3 months later.
2. 2. Clinical presentation: Diffuse hair thinning 3 months after a stressful event (major illnesses or surgery, pregnancy, severe weight loss)
3. 3. Treatment: Self-limited. Regrowth usually occurs over several months.

B. Alopecia Areata

1. 1. Clinical presentation: Chronic inflammatory (probably autoimmune) disease that starts with well-circumscribed small bald patches and normal-appearing underlying skin. New lesions may demonstrate subtle erythema and be pruritic. Bald patches may enlarge to involve large areas of the scalp or other hair-bearing areas. Many experience good hair regrowth within 1 to 2 years, although most will relapse. A minority progress to total loss of all scalp (alopecia totalis) and/or body hair (alopecia universalis).
2. 2. Diagnosis: Usually clinical diagnosis, but examination with magnification will show yellow dots, black dots, and exclamation point hairs. If diagnosis is unclear, a skin biopsy can also be obtained to confirm diagnosis.
3. 3. Treatment ¹³ : First-line therapy is topical steroids. Referral to dermatology is warranted for consideration of other treatments. No evidence-based data that any therapy is better than placebo. Older children, adolescents, and young adults with long-standing localized areas of hair loss have the best prognosis. New agents including JAK inhibitors show promise for treatment of resistant and/or persistent alopecia areata.

C. Traction Alopecia (Fig. 8.22, Color Plates)

1. 1. Pathogenesis: Hairstyles that apply tension for long periods of time
2. 2. Clinical presentation: Noninflammatory linear areas of hair loss at margins of hairline, part line, or scattered regions, depending on hairstyling procedures used
3. 3. Treatment: Avoidance of styling products or styles that result in traction. If traction remains for long periods, condition may progress to permanent scarring hair loss.

D. Trichotillomania and Hair Pulling

1. 1. Pathogenesis: Alopecia due to compulsive urge to pull out one’s own hair, resulting in irregular areas of incomplete hair loss. Mainly on the scalp; can involve eyebrows and eyelashes. Onset is usually after age 10 and should be distinguished from hair twirling/pulling in younger children that resolves without treatment in most cases.
2. 2. Clinical presentation: Characterized by hair of differing lengths; area of hair loss can be unusual in shape
3. 3. Treatment: Behavioral modification and consider psychiatric evaluation (can be associated with anxiety, depression, and obsessive-compulsive disorder)

V. Acne Vulgaris

A. Pathogenetic Factors
Follicular hyperkeratinization, increased sebum production, Cutibacterium acnes (formerly Propionibacterium acnes) proliferation, and inflammation

B. Risk Factors
Androgens, family history, stress, and medications such as topical and oral steroids, antidepressants, antiepileptics, cyclosporin, B vitamins. No strong evidence that dietary habits affect acne

C. Clinical Presentation

1. 1. Noninflammatory lesions
   1. a. Closed comedone (whitehead): Accumulation of sebum and keratinous material, resulting in white/skin-colored papules without surrounding erythema
   2. b. Open comedone (blackhead): Dilated follicles filled with keratinocytes, oils, and melanin
2. 2. Inflammatory lesions: Papules, pustules, nodules, and cysts with evidence of surrounding inflammation. Typically appear later in the course of acne. Nodulocystic presentations are more likely to lead to hyperpigmentation and/or permanent scarring.

D. Treatment^{14, 15, 16} (Table 8.2)
Topical minocycline foam, topical clascoterone (anti-androgen for males and females), encapsulated benzoyl peroxide and tretinoin, topical trifarotene (a fourth-generation retinoid approved for face and trunk)

1. 1. Skin care: Gentle nonabrasive cleaning. Avoid picking or popping lesions. Vigorous scrubbing and abrasive cleaners can worsen acne.
2. 2. Topical first-line therapies: Recommended for mild to moderate acne
   1. a. Retinoids (eTable 8.2)
      1. (1) Normalize follicular keratinization and decrease inflammation
      2. (2) A pea-sized amount should be applied to cover the entire face (not spot treatment). Avoid eyes, creases of nose. Start two to three times weekly, titrate to nightly as tolerated. Can take 2 months to see effect
      3. (3) Risks: Cause irritation and dryness of skin. Retinoids should be used at night because they can cause photosensitivity and decreased effectiveness when exposed to sunlight. Use daily SPF sunscreen. This class should not be used during pregnancy.
      4. (4) Three topical retinoids (tretinoin, adapalene, and tazarotene) are available by prescription in the United States. Adapalene 0.1% gel has been approved for over-the-counter (OTC) use with significant efficacy.¹⁷
   2. b. Benzoyl peroxide (BPO)
      1. (1) Oxidizing agent with antibacterial and mild anticomedolytic properties
      2. (2) Washes may be most convenient formulation, as they can be used in the shower.
      3. (3) Recommend daily use, typically in the morning.
      4. (4) Risks: Can bleach hair, clothing, towels, and sheets
   3. c. Salicylic acid: Topical comedolytic agent that may be found in OTC face washes and serves as an alternative to a topical retinoid
3. 3. Topical antimicrobials:
   1. a. Azelaic acid: Antimicrobial, comedolytic, and antiinflammatory. Recommended by the American Academy of Dermatology (AAD) for the treatment of postinflammatory dyspigmentation Available in a 15% gel and a 20% cream (more efficacious)¹⁸
   2. b. Erythromycin and clindamycin: Avoid topical antibiotics as monotherapy. Topical BPO should be concurrently used to optimize efficacy and avoid bacterial resistance.
   3. c. New topicals undergoing review are clascoterone and minocycline foam.
4. 4. Oral antibiotics (eTable 8.3): Recommended for moderate to severe inflammatory acne that is resistant to topical treatment. These medications should be used with BPO or topical retinoid. Do not use as monotherapy. Limit to 3 months to minimize bacterial resistance.
   1. a. ≥8 years old: Doxycycline or minocycline
   2. b. <8 years old, pregnancy, or tetracycline allergy: Azithromycin, erythromycin, or trimethoprim/sulfamethoxazole
   3. c. Erythromycin should be used with care due to increased risk of resistance. The AAD recommends reserving trimethoprim/sulfamethoxazole for patients who have failed other treatments or are unable to tolerate tetracyclines and macrolides.
5. 5. Hormonal therapy: Reduces sebum production and androgen levels. Good option for pubertal females who have sudden onset of moderate to severe hormonal acne (often on lower face, jawline) and have not responded to conventional first-line therapies. Should not be used as monotherapy. Combination oral contraceptives (see Chapter 5 for additional information) or spironolactone (antiandrogen)
6. 6. Oral isotretinoin: Reserved for patients with severe nodular, cystic, or scarring acne who do not respond to traditional therapy or who cannot be weaned from oral antibiotics. Should be managed by a dermatologist. Most patients have complete resolution of their acne after 16 to 20 weeks of use.
   1. a. Side effects:
      1. (1) Teratogenicity: Patients and physicians are mandated by the FDA to comply with the iPledge program to eliminate fetal exposure to isotretinoin. Female patients with child-bearing potential must use two forms of birth control with routine pregnancy testing.
      2. (2) Hepatotoxicity, hyperlipidemia, and bone marrow suppression, a complete blood cell count, fasting lipid profile, and liver function tests should be obtained before initiation of therapy and repeated at 4 and 8 weeks.

VI. Common Neonatal Dermatologic Conditions (; Figs. 8.23 To 8.30, Color Plates)

Fig. 8.21

A. Erythema Toxicum Neonatorum (Fig. 8.23, Color Plates)

1. 1. Clinical presentation: Most common rash of full-term infants; incidence declines with lower birth weight and prematurity. Appears as small erythematous macules and papules that evolve into pustules on erythematous bases. Rash most often occurs by 24 to 48 hours of life but can be present at birth or emerge as late as 2 to 3 weeks.
2. 2. Course: Self-limited, resolves within 5 to 7 days; recurrences possible

1. 1. Clinical presentation: More commonly affects full-term infants with darker pigmentation. At birth, appears as small pustules on nonerythematous bases that rupture and leave erythematous/hyperpigmented macules with a collarette of scale
2. 2. Course: Self-limited macules fade over weeks to months.

C. Miliaria (Heat Rash) (Fig. 8.26, Color Plates)

1. 1. Clinical presentation: Common newborn rash associated with warmer climates, incubator use, or occlusion with clothes/dressings. Appears as small erythematous papules or pustules usually on face, scalp, or intertriginous areas
2. 2. Course: Rash resolves when infant is placed in cooler environment or tight clothing/dressings are removed.

D. Milia (Fig. 8.27, Color Plates)

1. 1. Clinical presentation: Common newborn lesions. Appears as 1- to 3-mm white/yellow papules, frequently found on nose and face; due to retention of keratin and sebaceous materials in pilosebaceous follicles
2. 2. Course: Self-limited, resolves within first few weeks to few months of life

E. Neonatal Acne (Fig. 8.28, Color Plates)

1. 1. Clinical presentation: Seen in 20% of infants. Appears as inflammatory papules or pustules without comedones, usually on face and scalp. Secondary to effect of maternal and endogenous androgens on infant’s sebaceous glands
2. 2. Course: Peaks around 1 month, resolves within a few months, usually without intervention. Does not increase risk of acne as an adolescent

F. Seborrheic Dermatitis (Figs. 8.29 to 8.30, Color Plates)

1. 1. Clinical presentation: Erythematous plaques with greasy yellow scales. Located in areas rich with sebaceous glands, such as scalp, cheeks, ears, eyebrows, intertriginous areas, diaper area. Unknown etiology. Can be seen in newborns, more commonly in infants aged 1 to 4 months. Can also be seen in older patients, particularly adolescents with chronic medical conditions
2. 2. Course: Self-limited and resolves within a few weeks to months
3. 3. Treatment: Can remove scales on scalp with an emollient (e.g., mineral or olive oil, or petroleum jelly) and a soft brush/fine comb. In more severe cases, antifungal shampoos or low-potency topical steroid can shorten the course, although no shampoos are FDA approved for children less than 2 years of age.

G. Congenital Dermal Melanocytosis

1. 1. Clinical presentation: Most common pigmented lesion of newborns, usually seen in babies with darker skin tone. Appear as blue/gray macules without definite disappearance of dermal melanocytes. Can be mistaken for child abuse; thus accurate documentation at newborn and well-child visits is important
2. 2. Course: Spots typically fade within first few years of life, with majority resolved or much improved by age 10 years.
3. 3. Other types: Nevus of Ota involves the skin innervated by the first and second divisions of the trigeminal nerve and can cause neurocutaneous melanosis with up to 10% of patients developing sensorineural hearing loss or glaucoma ipsilateral to the skin lesion. Nevus of Ito involves the skin innervated by the posterior supraclavicular and lateral brachiocutaneous nerves.

H. Diaper Dermatitis¹⁹

1. 1. Clinical presentation: Irritant contact dermatitis characterized by erythematous eruption on buttocks and genital areas with exclusion of other potential causes. Most commonly associated with increased loose stools from viral gastroenteritis, antibiotics, and other gastrointestinal disorders. Rarely associated with diaper candidiasis, characterized by a red, raised papular rash with small pustules at the periphery (Fig. 8.31). Tends to involve the skin prominences and spares the protected skin creases¹⁹
2. 2. Treatment: Frequent diaper changes, air exposure, adequate drying, gentle cleaning, and judicious use of topical barrier preparations. If persistent, can use low-potency topical steroid until cleared no more than twice daily. For candidiasis, treatment with topical nystatin, miconazole, or clotrimazole is sufficient. Combination steroid/antifungal creams should be avoided due to steroid-related side effects and association with persistent fungal infections.²⁰

VII. Autoimmune and Allergic Dermatologic Conditions

A. Contact Dermatitis

1. 1. Irritant dermatitis: Exposure to physical, chemical, or mechanical irritants to the skin. Common irritants include frequent hand washing, hot water, lip-licking, thumb-sucking, and exposure to chemicals, paints, or certain foods like citrus fruits.
2. 2. Allergic dermatitis
   1. a. Pathogenesis: Immune reaction to an environmental trigger that comes into contact with the skin. After initial sensitization period of 7 to 10 days in susceptible individuals, an allergic response occurs with subsequent exposures.
   2. b. Common allergens: Toxicodendron spp. (poison ivy, oak, sumac), nickel, cobalt, gold, dyes, fragrances, formaldehyde, latex, and acetophenone azine (found in shin guards and other sports equipment)
   3. c. Dermatitis that can progress to chronic scaling, lichenification, and pigment changes. Poison ivy (Fig. 8.32, Color Plates): Exposure to urushiol causes streaks of erythematous papules, pustules, and vesicles. Highly pruritic, can become edematous, especially if rash is on face or genitals. In extreme cases, anaphylaxis can occur.
   4. d. Diagnosis: Careful history taking and recognition of unusual shapes and locations suggesting an “outside job” allow for clinical diagnosis. Patch testing may also be helpful when trigger cannot be identified.
   5. e. Treatment:
      1. (1) Remove causative agent. Moisturize with ointment like Vaseline or Aquaphor twice per day. Use antihistamine and/or oatmeal baths as needed for itching, sedation, and sleeping, though they do not directly impact the rash.
      2. (2) Mild/moderate: Topical steroids twice a day for 1 week, then daily for 1 to 2 weeks
      3. (3) Widespread/severe: Systemic steroids for 2 to 3 weeks, with taper. There is no role for short courses of steroids because eruption will flare when drug is stopped.
      4. (4) For poison ivy contact, remove clothing and wash skin with mild soap and water as soon as possible.

B. Atopic Dermatitis (Eczema) (Figs. 8.33 to 8.36, Color Plates)

1. 1. Pathogenesis: Due to inadequate skin barrier function from combination of genetic and environmental factors, resulting in transepidermal water loss and immunologically mediated inflammatory reaction. Can be associated with elevated serum IgE
2. 2. Epidemiology ²¹ : Affects up to 20% of children in the United States, the vast majority with onset before age 5 years. Other comorbidities may follow, including asthma, allergic rhinitis, and food allergies. Eczema resolves or improves in over 75% of patients by adulthood.
3. 3. Clinical presentation: Dry, pruritic skin with acute changes, including erythema, vesicles, crusting, and chronic changes, including scaling, postinflammatory hypo- or hyperpigmentation (eFigs. 8.1 and 8.2), and lichenification
   1. a. Infantile form: Erythematous, scaly lesions on the cheeks, scalp, and extensor surfaces. Covered areas (especially the diaper area) are usually spared.
   2. b. Childhood form: Lichenified plaques in flexural areas
   3. c. Adolescence: More localized and lichenified skin changes. Predominantly on skin flexures, hands, and feet
4. 4. Treatment ²¹ : See Chapter 15.
   1. a. Lifestyle: Avoiding triggers (products with alcohol, fragrances, astringents, sweat, allergens, and excessive bathing). Avoid scratching (eczema is the “itch that rashes”).
   2. b. Bathing: Should be less than 5 minutes in lukewarm water with a gentle bar soap and no washcloth or scrubbing. Skin should be patted dry (not rubbed) and followed by rapid application of an emollient (“soak and smear”).
   3. c. To reduce the risk of secondary infection, consider diluted bleach baths once or twice a week (mix ¼ cup of bleach in full tub of lukewarm water and soak for 10 minutes, then rinse off with fresh water).
   4. d. Skin hydration: Frequent use of bland emollients with minimal water content (Vaseline or Aquaphor). Avoid lotions, as they have high water and low oil content, which worsens dry skin. Consider “wet dressings” in severe cases to increase absorption of medication and moisturization. After bathing, apply steroid ointment, then moisturizer, prior to clothing child in warm, damp pajamas. Follow with second layer of dry pajamas and remove after several hours or overnight.
   5. e. Oral antihistamines: There is little evidence that antihistamines improve skin lesions in atopic dermatitis. Nonsedating antihistamines can be used for environmental allergies and hives. Sedating antihistamines may be of transient benefit for sedation at bedtime.
   6. f. Treatment for inflammation:
      1. (1) Mild disease: Topical steroids²² (Table 8.3): Low- and medium-potency steroid ointments once or twice daily for 7 days during a flare. Severe flares may require a high-potency steroid for a longer duration of therapy, followed by a taper to a low-potency steroid. Use of topical steroids in areas where skin is thin (groin, axilla, face, under breasts) should generally be avoided. Short durations of low-potency steroids may be used as needed in these areas. Ointments can be applied over steroid. Avoid overuse of steroids, as this can lead to chronic hyperpigmentation or hypopigmentation. Ensure that long-term eczema patients have frequent breaks from daily steroid use, such as week on and week off. Nonsteroidal topical agents may be used in sensitive areas; see below.
      2. (2) Moderate disease: Crisaborole is a topical PDE4 inhibitor approved for mild to moderate eczema, with preliminary studies of the 2% ointment showing improvement in the majority of clinical signs and symptoms, particularly pruritus.²³ Topical calcineurin inhibitors ( tacrolimus ointment, pimecrolimus cream) are second-line therapies that should only be used in consultation with a dermatologist due to FDA “black box” warnings on these medications for theoretical increased risk of cancer, although there are no data to confirm, and long-term safety studies are pending.^24,25
      3. (3) Severe disease: Phototherapy with narrowband UVB light is a treatment option for older children and adolescents. Low-dose methotrexate is a consideration before cyclosporine. For many dermatologists, low-dose oral methotrexate is the first oral option for severe disease unresponsive to aggressive topical therapy. Oral cyclosporine is only used in severe cases of older children and adolescents who have failed other treatments due to concern for renal compromise. Dupilumab is an IL-4 receptor α antagonist prescribed for refractory cases, starting at age six. A number of new agents, including topical and oral JAK and interleukin inhibitors, are in clinical trials.
5. 5. Complications ²⁶ :
   1. a. Bacterial superinfection: Usually S. aureus, sometimes group A Streptococcus. Depending on extent of infection, treat with topical mupirocin or systemic antibiotics.
   2. b. Eczema herpeticum superinfection with herpes simplex virus can cause severe systemic infection. Presents as vesiculopustular lesions with central punched-out erosions that do not respond to oral antibiotics. Must be treated systemically with acyclovir or valacyclovir. Should be evaluated by ophthalmologist if there is concern for eye involvement.
   3. c. Many children with eczema can develop decreased quality of life such as problems with sleeping due to discomfort and bullying due to scaring and disfigurement.

C. Papular Urticaria (Fig. 8.37, Color Plates)

1. 1. Pathogenesis: Type IV hypersensitivity reaction to fleas, mosquitos, or bedbugs; also known as insect bite–induced hypersensitivity (IBIH)
2. 2. Clinical presentation/epidemiology: Summarized by the SCRATCH principles²⁷
   1. a. Symmetric eruption: Exposed areas and scalp commonly affected. Spares diaper region, palms, and soles
   2. b. Cluster: Appear as “meal clusters” or “breakfast, lunch, and dinner,” which are linear or triangular groupings of lesions. Associated with bedbugs and fleas
   3. c. Rover not required: A remote animal exposure or lack of pet at home does not rule out IBIH.
   4. d. Age: Tends to peak by age 2. Not seen in newborn period. Most tend to develop tolerance by age 10.
   5. e. Target lesions: Especially in darkly pigmented patients. Time: Emphasize chronic nature of eruption and need for patience and watchful waiting.
   6. f. Confused pediatrician/parent: Diagnosis often met with disbelief by parent and/or referring pediatrician
   7. g. Household: Because of the nature of the hypersensitivity, usually only affects one family member in the household
3. 3. Management (3 Ps):
   1. a. Prevention: Wear protective clothing, use insect repellent when outside (AAP guidelines recommend up to 30% DEET- or 12% picaridin-containing repellents), launder bedding and mattress pads for bedbugs, and maximize flea control for pets.
   2. b. Pruritis control: Topical steroids or antihistamines may be of some benefit.
   3. c. Patience: Can be frustrating because of its persistent, recurrent nature. Assure patients that their symptoms will resolve and they will eventually develop tolerance.

D. Stevens-Johnson Syndrome and Toxic Epidermal Necrolysis

1. 1. Pathogenesis:

Severe mucocutaneous reaction with partial to full epidermal necrosis due to keratinocyte necrosis. Stevens-Johnson syndrome (SJS) has less than 10% involvement of body surface area (BSA), whereas toxic epidermal necrolysis (TEN) has greater than 30% BSA involvement. BSA involvement between 10% to 30% is termed SJS/TEN. Overall mortality for pediatric patients is less than 8%. Commonly caused by medications initiated in previous 8 weeks, including sulfonamide antibiotics, lamotrigine, carbamazepine, phenobarbital, and several oncologic drugs. May also be caused by Mycoplasma pneumonia infections. Nearly one-third of cases have no identified trigger.

1. 2. Clinical presentation:

Fever and flu-like prodrome for 1 to 3 days prior to mucocutaneous lesions. Ophthalmologic and oropharyngeal symptoms are often first sites of mucosal involvement. Urogenital mucosal involvement seen in two-thirds of patients may lead to urinary retention and have significant long-term anatomic changes in female patients. Epidermal lesions are described as exquisitely tender (with pain out of proportion), ill-defined, coalescing macules and patches of erythema with central purple-to-black areas. Lesions typically start on face and trunk then spread in a symmetric distribution sparing the scalp, palms, and soles. Bullae form with disease progression. Then, the epidermis sloughs with positive Nikolsky and Asboe-Hansen (lateral expansion of bullae with pressure) signs. Acute phase may last 8 to 12 days with reepithelization requiring up to four weeks.

1. 3. Diagnosis:

Although usually not necessary, clinical diagnosis may be confirmed with a skin biopsy. Additional workup includes Complete blood count (CBC), comprehensive metabolic panel (CMP), erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), bacterial and fungal cultures, M. pneumoniae PCR, and Chest x-ray (CXR).

1. 4. Treatment:

Remove offending agent, supportive care, and close monitoring of all organ systems in the inpatient/ICU setting. There is controversy regarding IVIG and single dose of tumor necrosis factor alpha (TNF-alpha) inhibitor early in course. Systemic steroids probably should not be used.

1. 5. Complications:

At risk for serious complications, including secondary bacterial infections (Staphylococcus aureus and Pseudomonas aeruginosa), septic shock, pneumonia, acute respiratory distress syndrome (ARDS), and epithelial necrosis of the GI tract. Most common complication in children is corneal scarring and dry eye.

VIII. Nail Disorders

Section references: 28

1. 1. Acquired nail disorders
   1. a. Paronychia: Red, tender, purulent swelling of proximal or lateral nail folds (^{eFIGURE 8.3 eFIGURE 8.4})
      1. (1) Acute form: Caused by bacterial invasion after trauma to cuticle
         1. (a) Clinical features: Exquisite pain, sudden swelling, and abscess formation around one nail
2. 2. Congenital/hereditary nail disorders
   1. a. Isolated nail disorders (^{eFIGURE 8.5 eFIGURE 8.6})
      1. (1) Congenital nail dystrophy: Clubbing and spooning (koilonychia), may be autosomal dominant with no other anomalies

IX. Disorders of Pigmentation

Section references: 29

1. 1. Hyperpigmentation
   1. a. Congenital melanocytic nevi (CMN): Melanocytic nevi that are either present at birth or appear within the first few months of life in 1% to 3% of neonates³⁰
      1. (1) Appearance: Black or tan with irregular borders and often dark terminal hairs
      2. (2) Risks:
         1. (a) Melanoma—At least 5% of large CMN greater than 20 cm with 70% of this cohort having cancerous transformation by 10 years of age.³¹ The presence of approximately 20 satellite nevi (smaller congenital nevi) also increases risk of melanoma.
         2. (b) Neurocutaneous melanosis—Children with large, multiple, satellite nevi, or lesions over the spine are at risk for leptomeningeal involvement with symptoms that may include hydrocephalus and seizures that may require evaluation by gadolinium contrast MRI.^32,33
   2. b. Epidermal melanosis: Most lesions appear tan or light brown
      1. (1) Café-au-lait spots (eFig. 8.1): Discrete tan macules that appear at birth or during childhood in 10% to 20% of normal individuals, sizes vary from freckles to patches, may involve any site on skin. May be diagnostic marker for neurofibromatosis type 1 (≥6 lesions, each greater than 5 mm in diameter in prepubertal, or greater than 15 mm in postpubertal child) or other syndromes
2. 2. Hypopigmentation and depigmentation
   1. a. Localized hypopigmentation
      1. (1) Hypopigmented macules (eFig. 8.7)
         1. (a) Epidemiology: 0.1% to 0.5% of normal newborns have a single hypopigmented macule, but it may be a marker for tuberous sclerosis as 70% to 90% of those affected have such macules on the trunk at birth.
3. 3. Dyspigmentation
   1. a. Blaschkoid dyspigmentation³⁴: Congenital hypopigmentation and hyperpigmentation along the lines of Blaschko (eFig. 8.8)
      1. (1) Patterns of hyper- or hypopigmentation: Whorl shape on trunk, V shape on the back, waves on the vertex scalp

X. Rashes of Unknown or Inflammatory Etiology

1. 1. Pityriasis lichenoides et varioliformis acuta (PLEVA) and pityriasis lichenoides chronica (PLC)
   1. a. Pathogenesis: Spectrum of rare disorders known as the “pityriasis lichenoides” separated into acute and chronic forms. Pathogenesis theorized to involve T-cell dyscrasia and abnormal immune response to viral, bacterial, or protozoal infection
   2. b. Presentation: Typically affects children and young adults. PLEVA is an acute eruption of multiple erythematous macules, papules, and/or vesicles, which can become hemorrhagic or necrotic, affecting any cutaneous surface but without mucosal involvement. Lesions resolve over a few weeks, but new lesions develop as prior lesions fade. The rash may be asymptomatic, pruritic, or painful and last from a few weeks to 2 years. Some patients can go on to develop PLC, which is described as a more gradual development of red-brown papules that relapses and remits over months to years. In both conditions, hyper- or hypopigmentation commonly persists after resolution of lesions, but scarring may or may not occur.
   3. c. Diagnosis: Skin biopsy is required to confirm diagnosis with typical histopathologic findings. Immunohistochemistry may reveal CD8+ T-cell inflammatory infiltrate.
   4. d. Treatment: Usually benign and self-limiting and does not require treatment. If lesions are widespread, debilitating, or scarring, first-line therapies include systemic antibiotics and topical corticosteroids. Limited treatment data exist due to rarity of disorder and lack of clinical trials. Resistant cases may respond to phototherapy.
2. 2. Confluent and reticulated papillomatosis (CARP) (Fig. 8.38, Color Plates)
   1. a. Pathogenesis: Unknown, but possibly related to disordered keratinization resulting in hyperproliferation. Reports also link CARP to Malassezia infection
   2. b. Presentation: Hyperpigmented, scaly macules and/or papillomatous papules that coalesce into patches in a reticular pattern. Lesions are typically most prominent in the intermammary, interscapular, neck, and axillary regions, and spare the mucosa. The rash can be mildly pruritic but is usually asymptomatic and can persist for up to 3 years if not treated.
   3. c. Diagnosis: Clinical diagnosis, but KOH scraping to rule out tinea may be necessary. Skin biopsy can be helpful, but there are no diagnostic histologic findings for CARP.
   4. d. Treatment: Systemic antibiotic therapy with doxycycline or minocycline is the mainstay of treatment. Benefits are attributed to the antiinflammatory properties, rather than antibacterial, as no specific bacterial cause has been identified.
3. 3. Giannoti-Crosti syndrome, or popular acrodermatitis of childhood
   1. a. Pathogenesis: Possibly related to viral illness such as Epstein-Barr virus (most common trigger in the United States) or hepatitis B (most common trigger in Europe). There may be an association with IgE-mediated immunity and atopy.
   2. b. Presentation: Occurs primarily in children younger than 5 years old. Acute eruption of papules and vesicles involving the extensor surfaces of arms, legs, and feet, with involvement of face and buttocks. The trunk is relatively spared, and the mucosa is not involved. The lesions are flat-topped and typically either skin colored, pink, or brown. Symptoms of pruritis are variable. Occasionally, hemorrhagic lesions can occur, and Koebner phenomenon has been observed. Patients may experience concomitant malaise, fever, and diarrhea.
   3. c. Diagnosis: Clinical diagnosis, but skin biopsy may be used to exclude other diagnoses
   4. d. Treatment: Self-limited disease that resolves within 2 months. Antipruritic topical creams may be used for symptomatic relief but do not alter duration of disease.

H. Autoimmune Bullous Diseases: See Section XI, Online Content.

XI. Online Content

A. Autoimmune and Allergic Lesions

1. 1. Autoimmune bullous diseases
   1. a. Very rare in children but should be considered if bullous lesions do not respond to standard therapy. Suspicion for any of the following should warrant referral to a dermatologist for diagnosis and management.
   2. b. Pemphigus vulgaris (eFig. 8.9):
      1. (1) Pathogenesis: IgG autoantibodies to epidermal adhesion molecules, which interrupt integrity of epidermis and/or mucosa and result in extensive blister formation
      2. (2) Clinical presentation: Flaccid bullae that start in the mouth and spread to face, scalp, trunk, extremities, and other mucosal membranes. Positive Nikolsky sign. Ruptured blisters are painful and prone to secondary infection. Can lead to impaired oral intake if there is significant oral mucosal involvement
      3. (3) Treatment: Systemic glucocorticoids, rituximab, and/or intravenous immunoglobulin

Author(s)

Allison Haley, MD, Katherine Cummings, MD

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