Pediatric Residency Training Program

19

Dermatology

Harry W. Saperstein M.D.

Lloyd J. Brown M.D.

  1. General Concepts
  2. Skin examination

should be conducted in good light and should be complete, including evaluation of the scalp, hair, nails, eyes, mouth, palms, and soles. Examination should be both visual and tactile.

  1. Description

of skin disease requires identification of primary lesions and any secondary characteristics. Configuration and distribution of lesions should also be noted.

  1. Primary lesions
  2. Maculesare flat and nonpalpable and represent a cutaneous color change. A patch is a large macule.
  3. Papulesare epidermal or superficial dermal lesions that are elevated above the skin surface. A plaque describes large or coalesced papules.
  4. Nodulesare dermal lesions that are generally below the skin surface, although they may have an epidermal component that rises above the skin surface. A tumor is a large nodule.
  5. Vesiclesare fluid-filled papules. A bulla is a large vesicle.
  6. Pustulesare purulent-filled papules.
  7. Cystsare nodules filled with expressible material.
  8. Whealsare cutaneous elevations caused by dermal edema.
  9. Secondary characteristicsinclude:
  10. Scaling:desquamation of the stratum corneum
  11. Crusting:dried exudate and debris
  12. Pigmentation changes
  13. Excoriations:linear erosions into the epidermis caused by fingernail scratches
  14. Scars:thickened fibrotic dermis
  15. Ulcers:absence of epidermis and some of the dermis
  16. Atrophy:thinning of the epidermis or dermis
  17. Fissures:linear cracks into the dermis

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  1. Configuration and distribution
  2. Configuration of lesionsmay be described as linear, annular (i.e., in circles), arcuate (i.e., in half-circles), grouped, or discrete (i.e., distinct and separate).
  3. Distributionsinclude generalized, acral (hands, feet, buttocks), confined to a dermatome, or other specific locations.
  4. Diagnostic Procedures
  5. Woods lightcan identify pigmentary changes and some dermatophytes.
  6. Scrapings
  7. Fungus.Ten percent potassium hydroxide (KOH) can be added to a scraping of a scale or exudate to identify fungal hyphae.
  8. Scabies.Examination under a microscope of a scraping of an unscratched lesion or burrow for mites, eggs, or feces may be diagnostic of scabies.
  9. Herpes simplex virus(HSV). The base of a vesicle can be scraped for laboratory identification of the herpes virus.
  10. Culturesmay be obtained for bacteria, virus, and fungus.
  11. Invasive techniques
  12. Incision and drainagemay be performed for diagnosis, to obtain cultures, or for therapy.
  13. Biopsy
  14. Shave or tangentialbiopsy for epidermal and superficial dermal lesions
  15. Punchbiopsy for epidermal, dermal, and superficial subcutaneous lesions
  16. Excisionbiopsy for complete lesion removal
  17. Immunofluorescent stainingof biopsied lesions may be useful in autoimmune vasculitic disorders.
  18. Management
  19. General concepts
  20. Absorptionof topical agents through the skin of a child is equal to the absorption through the skin of an adult, except in a premature infant in whom absorption is greater because of a thinner stratum corneum.
  21. Therapeutic efficacyof a topical agent is related to both the active ingredient and the vehicle (e.g., cream, lotion, ointment).
  22. Hydration of the skin is critical.Dry, irritated skin is a poor barrier and easily damaged. Moisturizers include:
  23. Ointmentscontain little or no water and have maximal water-retaining properties, making them useful for very dry skin.
  24. Creamscontain 20–50% water and are useful for skin of average dryness.
  25. Lotionscontain more water than creams and are useful for minimally dry skin or for large surface areas.
  26. Solutionsand alcohol-based gels are most useful for areas with hair (e.g., scalp).

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  1. Thickened skin(hyperkeratosis) requires keratolytics, such as sali-cylic acid, urea, α-hydroxy acids, and retinoic acid.
  2. Destructive therapies(e.g., for warts, molluscum contagiosum) include high-dose salicylic acid, podophyllin, 5-fluorouracil, cryotherapy, electrotherapy, and laser therapy.
  3. Anti-infective agentsinclude topical antibiotics, antifungals, antivirals, and antiparasitic agents.
  4. Anti-inflammatory agents
  5. Topical corticosteroidsare categorized on the basis of their vehicle and potency. Effectiveness and potential side effects mirror steroid potency. The weakest steroid that will achieve the treatment goal should be used first. In general, only low-potency corticosteroids should be used on the face or groin because the epidermis is thinner in these areas, resulting in an increased risk of side effects.
  6. Systemic side effects.Systemic steroid levels can be achieved if very potent steroids are used on damaged or thin skin for longer than 2 weeks. Effects include adrenal suppression, depressed growth, cataracts, glaucoma, and Cushing syndrome (see also Chapter 6, section IV.E.2.b).
  7. Local side effectsare more common and may occur after only a few days of treatment.
  8. Acne(acne rosacea)
  9. Hirsutism
  10. Folliculitis
  11. Striae(especially in axilla or groin)
  12. Hyper- or hypopigmentation
  13. Atrophy
  14. Ecchymoses and telangiectasias
  15. Tachyphylaxis(insensitivity to the medication)
  16. Other anti-inflammatory agents
  17. Tacrolimus ointment, an immunomodulator, for atopic dermatitis
  18. One to five percent sulfur, formulated with other medications, for acne
  19. Tar, used for eczema and psoriasis
  20. Newborn Skin Diseases

(see Chapter 4, section I.B)

III. Inflammatory Disorders

  1. Contact Dermatitis
  2. Definition.Contact dermatitis is inflammation of the epidermis and superficial dermis secondary to direct contact with the skin by a sensitizing substance.
  3. Categories

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  1. Allergic contact dermatitis
  2. Etiology.Allergic contact dermatitis occurs as a direct T-cell–mediated response to an exogenous applied allergen. There must be an initial sensitization and then a rechallenge (which may be very small and is not dose-dependent) to elicit a reaction. Common causes include poison ivy, oak, or sumac; nickel-containing jewelry and belt buckles; topical lotions and creams; and perfumes and soaps.
  3. Clinical features.Erythematous papules and vesicles occur in the area that came into contact with the allergen.
  4. Management.Treatment involves topical corticosteroids and avoidance of the offending allergen.
  5. Primary irritant contact dermatitis
  6. Etiology.Primary irritant contact dermatitis is caused by caustic substances that irritate the skin, rather than an allergic reaction. No prior sensitization is needed. The reaction is dose-dependent. The most common type is diaper dermatitis, a multifactorial disorder caused by prolonged contact with urine and fecal matter, friction, maceration, and proteases contained in the feces. Secondary infection with Candida albicans may occur.
  7. Clinical featuresof diaper dermatitis include erythema with papules on the upper thighs, buttocks, and genitourinary area without involvement of the inguinal creases.Involvement of the inguinal creases, more-intense confluent erythema, and satellite lesions all suggest candidal superinfection.
  8. Managementof diaper dermatitis includes keeping the skin free from urine and stool, skin moisturizers, barrier creams and ointments (e.g., zinc oxide), and frequent diaper changes. Low-potency corticosteroids may be used for severe inflammation. Candidal infection may be treated with antifungal medication (e.g., nystatin, clotrimazole).
  9. Atopic Dermatitis

(see Chapter 15, section III)

  1. Seborrheic Dermatitis
  2. Epidemiology.Seborrheic dermatitis predominantly affects two age groups, infants and adolescents.
  3. Etiology.The cause is unknown but may in part be the result of a hypersensitivity reaction to a saprophytic yeast (Pityrosporum ovale) that lives in areas that overproduce sebum.
  4. Clinical features.Eruption of red scales and crusts in areas with high numbers of sebaceous glands, such as the scalp, face (including the eyebrows, nose, and beard area), chest, and groin. Skin lesions may be greasy.
  5. Infantsmay have dermatitis limited to the scalp, termed seborrheic capitis, or cradle cap. This may also involve the face, upper chest, and flexor creases of the extremities.
  6. Adolescentsmay have dermatitis in the nasolabial folds, pinna, and scalp.

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  1. Management
  2. Low-potency topical corticosteroids
  3. Sulfur, zinc, or salicylic acid-basedshampoos may be applied, followed by light scrubbing with a brush to remove crusts. Loose scales may also be removed with mineral oil.
  4. Topical antifungal medicationto eradicate Pityrosporum ovale
  5. Pityriasis Rosea
  6. Epidemiology.Pityriasis rosea is uncommon before 5 years of age but is extremely common during late childhood and adolescence.
  7. Etiology.The cause is unknown, although it clinically appears similar to a hypersensitivity reaction to a virus.
  8. Clinical features
  9. Papulosquamousdisorder that begins with a solitary, large 2- to 5-cm scaly, erythematous lesion (herald patch) that is usually located on the trunk or extremities. The herald patch is present for 1–30 days.
  10. Approximately 1–2 weeks after the appearance of the herald patch, oval erythematous macules and papuleserupt for 3–6 weeks from the chin to the mid-thigh, following skin lines in a “Christmas tree” distribution on the trunk.
  11. Lesions are pruritic in 50% of cases.
  12. Management.Treatment may include topical or systemic antihistamines. Exposure to ultraviolet light may shorten the disease course.
  13. Psoriasis
  14. Epidemiology.Psoriasis occurs in 3% of children in the United States. Although it is more common in adults, 30% of patients develop signs and symptoms during childhood.
  15. Etiology.Childhood-onset psoriasis is often a genetic disease with autosomal dominant inheritance. It is caused by immune dysregulation, causing epidermal proliferation.
  16. Clinical features
  17. Distribution of skin lesions and severity are variable. If severe, psoriasis may be disfiguring.
  18. Lesions are characterized by scaling papules and plaquesoften found on the scalp (nongreasy scaling without hair loss), ears, elbows, knees, lumbosacral area, and groin. Some lesions have a classic silvery scale.
  19. Lesions often demonstrate the Koebner phenomenonin which new lesions develop at sites of skin trauma.
  20. Nail involvement is commonand may include pits, distal thickening, lifting of the nail bed, and nail destruction.
  21. Arthritisduring childhood is uncommon.
  22. Management.Treatment may include moderate- or high-potency corticosteroids, ultraviolet light therapy, analogs of vitamin D, 3% salicylic acid in mineral oil for scalp involvement, retinoids, and anthralin (downregulates epidermal growth factor).

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  1. Miliaria Rubra (Heat Rash)
  2. Etiology.Heat rash is caused by disrupted sweat ducts near the upper dermis (often caused by occlusion or friction) that result in sweat being released onto the skin. The sweat on the skin produces an inflammatory response. Therefore the more sweat produced and the more occlusion, the more likely heat rash will develop.
  3. Clinical features.Small erythematous pruritic papules or vesicles occur in areas of occlusion or in areas that have been rubbed, such as the inguinal region, axilla, chest, and neck.
  4. Management.Treatment is avoidance of occlusive clothing to decrease sweating. Medications are unnecessary.
  5. Hypersensitivity Disorders
  6. Urticaria

(see Chapter 15, section VI).

  1. Serum sickness

may initially appear as urticaria but has systemic signs and symptoms such as fever, arthralgias, and adenopathy and evidence of organ injury. Medications, such as cephalosporins, are common causes.

  1. Erythema Multiforme
  2. Definition.Erythema multiforme is a hypersensitivity reaction to many possible stimuli, including drugs, viruses, bacteria, fungi, protozoa, and systemic disease.
  3. Categories.There are three major categories: erythema multiforme minor, erythema multiforme major, and Stevens-Johnson syndrome. The classic skin lesion present in all cases is a target lesion, a fixed, dull red, oval macule with a dusky center that may contain a papule or vesicle. Table 19-1 summarizes the causes, clinical features, management, and prognosis of each type of erythema multiforme.
  4. Toxic Epidermal Necrolysis

is a severe reaction to drugs (e.g., anticonvulsants, antibiotics, anti-inflammatory drugs) that results in widespread epidermal necrosis. Clinical features include sloughing of the epidermis (usually > 30% skin loss) and severe mucous membrane involvement. No target lesions are usually seen. Nikolsky sign (skin peels away with lateral pressure) is often present. Mortality is high (10–30%) as a result of the high incidence of sepsis, dehydration, and electrolyte abnormalities.

  1. Infections of the Skin
  2. Fungal (Dermatophyte) Infections
  3. Epidemiology.Fungal infections are common during childhood and are most associated with humidity and with urban and crowded living conditions.
  4. Categories.Fungal infections can involve the hair, skin, or nails.
  5. Tinea capitisis a fungal infection of the hair.

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  1. Etiology.Tinea capitis is most commonly caused by Trichophyton tonsurans (95%), acquired from human-to-human contact, and Microsporum canis (5%), acquired from cats and dogs.
  2. Clinical features
  3. Patchy hair lossin which the hairs break off at the scalp (black dot ringworm) or in which the broken hairs are thickened and white (seen in M. canis infection).

Table 19-1. Characteristic Features of the Types of Erythema Multiforme

 

Erythema Multiforme Minor

Erythema Multiforme Major

Stevens-Johnson Syndrome

Major cause

Herpes simplex virus

Mycoplasma pneumoniae; Drugs

Drugs

Skin findings

Symmetric target lesions; acral distribution

Typical symmetric target lesions;acral and truncal distribution

Widespread atypical, asymmetric target lesions, blisters, and necrosis

Mucous membrane findings

Occurs in 25%; only one surface involved (often mouth)

At least two mucosal surfaces involved (often mouth and eyes)

At least two mucosal surfaces involved (often mouth and eyes)

Systemic findings

Prodrome of low-grade fever, arthralgias, myalgias

Prodrome of low-grade fever, arthralgias, myalgias

Prodrome of high fever, cough, malaise, headache, arthralgias

Management

Supportive care

Supportive care

Supportive care

 

Acyclovir may prevent recurrence

Erythromycin or azithromycin if M. pneumoniae is suspected
Stop offending drug

Stop any offending drug Ophthalmology consultation
Consider steroids, IVIG, burn unit

Prognosis

Good; possible recurrence

Good

High morbidity and mortality (5%)

IVIG = intravenous immune globulin.

  1. Infected areas may have scalesand pustules.
  2. Kerion(large red boggy nodule) may be present and is a hypersensitivity reaction to the dermatophyte.
  3. Occipital and posterior cervical lymphadenopathyare very suggestive of tinea capitis.
  4. Diagnosis.The basis of diagnosis is microscopic evaluation of hairs with 10% KOH to identify fungal hyphae, or fungal culture. Hairs fluoresce under Woods light if M. canis is the infecting organism.
  5. Management.Treatment includes systemic oral antifungal therapy (e.g., griseofulvin) for 6–8 weeks. Topical antifungal agents are ineffective. Topical 2.5% or 5% selenium sulfide shampoo may reduce infectivity.
  6. Fungal infection of the skinmay include tinea corporis (infection on the body), tinea pedis (infection on the foot), and tinea cruris (infection in the groin).
  7. Etiology.Pathogens include M. canis, T. tonsurans, and other Trichophyton species.
  8. Clinical features
  9. Tinea corporis(“ringworm”) presents as oval or circular scaly erythematous patches with partial central clearing.
  10. Tinea pedis(athlete's foot) presents most commonly in postpubertal adolescents with scaling and erythema between the toes or on the plantar aspect of the foot. Vesicles may also be seen.
  11. Tinea crurispresents as scales and erythema in the groin and inguinal creases.
  12. Diagnosis.Clinical features are often the basis of diagnosis. KOH examination of skin scrapings for fungal hyphae or fungal culture can confirm the diagnosis.
  13. Management.Treatment includes topical antifungal medications (e.g., clotrimazole, terbinafine, ketoconazole).
  14. Tinea unguium (onychomycosis)is a fungal infection of the nails characterized by thickening and yellow discoloration of one or several nails (usually toenails). Topical management is challenging; treatment requires prolonged therapy and is often unsuccessful. Systemic medications, such as griseofulvin, terbinafine, and ketoconazole, have been used with varying success.
  15. Tinea versicoloris a superficial fungal disorder most common in adolescents and young adults. It is caused by Pityrosporum orbiculare, a yeast that invades the stratum corneum.

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  1. Clinical featuresvary and include fine, scaly oval macules on the trunk, proximal arms, and face. Macules may be hypo- or hyperpigmented and become more prominent with sun exposure. Infection may also be asymptomatic.
  2. Diagnosisis by identification of fungal hyphae or circular spores on KOH examination of a scraping of a lesion (“spaghetti and meatballs” appearance), or by yellow or orange fluorescence under Woods light evaluation.
  3. Management.Treatment includes overnight application of 2.5% selenium sulfide weekly for 3–4 weeks, ketoconazole shampoo or cream, or systemic antifungal medications.
  4. Bacterial infections

including impetigo, cellulitis, erysipelas, scarlet fever, toxic shock syndrome, and staphylococcal scalded skin syndrome, are discussed in Chapter 7, section IX.

  1. Viral Infections
  2. Viral exanthemrefers to a skin rash associated with a viral infection. Any virus may cause an exanthem, and the rash may take many forms. An enanthem (describes involvement of the oral mucosa) may also be present.
  3. Morbilliform:measles-like
  4. Scarlatiniform(scarlet fever–like): papular, vesicular, and petechial
  5. Measles and rubella(see Chapter 7, sections XIII.C and D)
  6. Erythema infectiosum (fifth disease)
  7. Epidemiology.Fifth disease is most common in school-age children, although cases can occur at any age.
  8. Etiology
  9. The cause is parvovirus B19.Fifth disease is transmitted by respiratory secretions.
  10. Parvovirus B19 infection may also cause aplastic crisis(especially in patients with hemoglobinopathies), prolonged anemia in immunosuppressed patients, and fetal hydropsor miscarriage in pregnant women.
  11. Clinical features
  12. Fifth disease begins with upper respiratory symptoms (cough, fever, rhinorrhea) that are followed 1–2 weeks later by a bright red macular rash on the cheeks (“slapped-cheek” appearance) that lasts several days. Patients are generally no longer contagious when the characteristic facial rash appears.
  13. Lacy, reticular rashon the trunk and extremities follows the facial rash and generally lasts 3–5 days. In some patients, exercise, heat, or sunlight can induce the lacy rash to recur.
  14. Arthralgiasmay be present, although they are more common in adults.
  15. Management.Treatment is supportive. However, intravenous immune globulin may be used treat chronic anemia in immunosuppressed patients.

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  1. Roseola infantum (exanthem subitum)
  2. Epidemiology.Roseola is most common in children younger than 2 years of age.
  3. Etiology.Roseola is most commonly caused by human herpes virus 6 and 7. Other causes include adenovirus, parvovirus B19, and echovirus 16.
  4. Clinical features.Roseola begins with 3–5 days of high fever. Once the fever resolves, a pink papular eruption occurs on the trunk that generally fades in 24–48 hours.
  5. Management.Treatment is supportive.
  6. Gianotti-Crosti syndrome (papular acrodermatitis) most often occurs in children younger than 3 years of age. Gianotti-Crosti is associated with hepatitis Binfection, Epstein-Barr virus, cytomegalovirus, and coxsackievirus. Clinical features include red or flesh-colored flat-topped papules in the acral areas (extremities, buttocks, and cheeks). Skin lesions may last for weeks and may recur. Upper respiratory symptoms may precede the eruption. Treatment is supportive.
  7. Varicella (chickenpox)
  8. Epidemiology.The incidence of varicella has decreased as a result of routine early childhood immunization in many states. Varicella may occur at any age in unimmunized children and adolescents.
  9. Clinical features
  10. Intensely pruritic erythematous macules develop acutely after a 7- to 21-day incubation period.The macules develop central vesicles within 1–2 days. The classic lesion is described as a “dew drop on a rose petal,” or a vesicle on a red background.
  11. Crops of lesionsappear during the course of 2–5 days, and the lesions soon crust. Hundreds of vesicles may be present.
  12. Fever is common.
  13. Management.Treatment includes antipyretics, cleansing with antibacterial soaps to prevent bacterial superinfection, antihistamines for itching, and monitoring and treating any complications. Acyclovir is generally administered intravenously for patients with varicella pneumonia and encephalitis, orally for those at high risk for complications and topically in the eyes for those with ophthalmic involvement.
  14. Complications(Table 19-2)
  15. Herpes simplex virus infection (HSV-1 and HSV-2)
  16. Pathophysiology
  17. Neonatalinfection is generally acquired during passage through the birth canal of a mother with primary HSV infection. Two thirds of neonatal infections are caused by HSV-2 and one third are caused by HSV-1.
  18. Gingivostomatitisis the most common HSV infection during infancy and childhood and is almost always caused by HSV-1.
  19. Clinical features
  20. Characteristic lesions are grouped vesicles on an erythematous base.

Table 19-2. Complications of Varicella Infection

Bacterial superinfection (often Staphylococcus aureus)
Necrotizing fasciitis (group A streptococcus)
Scarring
Reye syndrome (associated with ingestion of salicylates)
Pneumonia
Encephalitis
Acute cerebellar ataxia
Hepatitis
Herpes zoster
Infection during pregnancy:
Teratogenic effects (congenital varicella syndrome: zigzag scarring of the skin, shortened or malformed extremities, central nervous system damage, and eye abnormalities such as cataracts or chorioretinitis)
Severe varicella infection in a neonate may develop if mother acquires varicella within one week of delivery

  1. P.543
  2. HSV gingivostomatitispresents most often in young infants with grouped vesicles and ulcers on the lips, in the corners of the mouth, and on the tongue. Pain on swallowing, drooling, and fever may be present. Infection lasts 1–2 weeks.
  3. Neonatal HSVcommonly presents in the first week of life with variable signs and symptoms. Neonates may have only a few vesicles at the site (often the scalp) that was in contact with the infecting maternal lesion, or may present with signs and symptoms of sepsis, including apnea, lethargy, irritability, and seizures. Serious sequelae includemeningoencephalitis, hepatitis, sepsis, shock, and death.
  4. Herpetic whitlowdescribes HSV-1 infection of the thumb or fingers that is usually secondary to thumb- or finger-sucking by a child with an oral HSV lesion.
  5. HSV resides in the dorsal root ganglionafter initial infection and therefore recurrent HSV infection may occur. Recurrent HSV lesions are more mild and less symptomatic than primary infection and generally occur on the lip. Fever, sunlight, emotional stress, and trauma may all reactivate the latent virus.
  6. Diagnosis.HSV may be diagnosed by identification of epidermal giant cells on microscopic evaluation of a Tzanck preparation, by detection of HSV antigen on direct fluorescent antibody testing, or by culture of the base of the lesion. Polymerase chain reaction (PCR) technology is commonly used to identify HSV in the cerebrospinal fluid.
  7. Management
  8. Neonatal HSV infectionis a medical emergency and requires immediate hospitalization and treatment with intravenous acyclovir.
  9. Cutaneous and oral HSVmay be treated with oral acyclovir, although treatment must be started promptly to alter the disease course. Oral acyclovir, when given daily, may also prevent recurrent infection.

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  1. Hand-foot-mouth disease and herpangina
  2. Etiology.Hand-foot-mouth disease and herpangina are caused by infection with coxsackievirus types A16 (most common), A2, A5, and A10.
  3. Clinical featuresinclude vesicles, papules, or pustules on the palms, soles, or fingertips and shallow ulcers or erosions on the soft palate or tongue. If only oral lesions are present, the disorder is termed herpangina. Fever may occur with both forms.
  4. Management.Treatment is supportive.
  5. Warts
  6. Etiology.The cause is human papillomavirus.
  7. Clinical features.Warts may occur on any skin surface and appear as irregularly shaped discrete flesh-colored papules that may be smooth or rough. Warts often increase in size, are contagious, and may spread to adjacent skin. Condylomata acuminata is the term used to describe multiple external warts in the genital area (see Chapter 3, section VII.B.7).
  8. Management.Most warts resolve spontaneously within 1–2 years. Treatment to remove warts may include liquid nitrogen, salicylic acid, cantharidin, podophyllin, and surgical excision. Recurrence after any treatment is high.
  9. Molluscum contagiosum
  10. Etiology.The cause is a poxvirus.
  11. Clinical features
  12. Small asymptomatic flesh-colored papules with central umbilicationare characteristic.
  13. Lesions may be present anywhere on skin with hair follicles, although the face, proximal extremities, and trunk are most commonly involved.
  14. Lesions are contagious.
  15. HIV infectionmay be associated with extensive eruptions of molluscum.
  16. Management.Treatment is often observation with expected resolution without therapy. Removal can be accomplished by curettage or application of podophyllin, trichloroacetic acid, liquid nitrogen, salicylic acid, or cantharidin.
  17. Ectoparasites
  18. Louse infestationmay involve the scalp (head lice), body (body lice), or groin (pubic lice).
  19. Etiology.Causative organisms include Pediculus humanus, the cause of head and body lice, and Phthirus pubis, the cause of pubic lice. The louse is a small six-legged insect that attaches to the skin and ingests blood.
  20. Epidemiology.Louse infestations are associated with crowded living conditions and sharing of hats, clothes, combs, and hairbrushes.
  21. Clinical features
  22. Head liceare associated with itching. The nits (eggs) may be

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seen as oval white bodies attached to the hair shaft. The louse may be found on the scalp.

  1. Body liceare associated with papules and pustules on the trunk with excoriations.
  2. Pubic liceare associated with lice or nits in the groin and black-crusted papules or blue macules (macula cerulea).
  3. Management
  4. Head liceare treated with 1% permethrin shampoo and a comb to remove the nits. Five percent permethrin and malathion are sometimes used for resistant lice.
  5. Body and pubic liceare treated with a 12-hour application of 1% γ-benzene hexachloride lotion.
  6. Scabies
  7. Etiology.Scabies is caused by the mite Sarcoptes scabiei.
  8. Clinical features.Pruritic papules or vesicles are most commonly located on the abdomen, dorsum of the hands, groin, axilla, flexor surfaces of the wrists, and interdigital spaces. Infants may have facial and neck involvement. Itching is severe, and S-shaped burrows may be seen.
  9. Diagnosis.Microscopic examination of a scraping from an unscratched burrow demonstrating the mite, eggs, or mite feces is diagnostic.
  10. Management.Treatment includes an overnight application of 5% permethrin lotion, or 1% lindane (adolescents and adults only). Scabies is highly contagious, and therefore all household contacts should be treated. Itching may persist for up to 30 days after treatment. All bed sheets, pillowcases, and clothing should be washed in hot water.
  11. Pigmentary Disorders
  12. Hypopigmentation

Causes include the following:

  1. Postinflammatory hypopigmentationmay follow any skin inflammation (e.g., atopic dermatitis) and generally resolves over months to years.
  2. Pityriasis albais thought to be related to atopic dermatitis. It is characterized by hypopigmented, dry, scaly patches, most commonly on the cheeks. Treatment includes moisturizers and mild corticosteroids.
  3. Vitiligois a complete loss of skin pigment in patchy areas and is caused by melanocyte destruction. Partial repigmentation may sometimes occur. There is no effective treatment, although psoralen combined with ultraviolet light may be helpful.
  4. Oculocutaneous albinismis caused by a genetic defect in melanin synthesis. Clinical features include white skin and hair, blue eyes, and other eye findings, such as photophobia and nystagmus. There is no treatment.
  5. Neurocutaneous Disorders. Table 19-3

summarizes the clinical features of tuberous sclerosis and neurofibromatosis.

Table 19-3. Clinical Features of Neurocutaneous Syndromes

 

Tuberous Sclerosis

Neurofibromatosis Type 1 (NF-1)*

Inheritance

Autosomal dominant

Autosomal dominant

Skin findings

Ash-leaf spots (hypopigmented macules seen best under Woods light)
Angiofibromas on nose or face (adenoma sebaceum)
Shagreen patch(thickened orange peel appearance)
Ungual fibromas

Café-au-lait spots
Axillary or inguinal freckling
Plexiform neurofibroma or skin neurofibromas

CNS findings

Seizures (95%), including infantile spasms
Intracranial calcifications
Cortical or subependymal tubers

Optic glioma (usually present by age 3)
Intracranial calcifications
CNS neurofibromas

Systemic findings

Renal cysts
Cardiac rhabdomyomas number one cause of neonatal cardiac tumors
Retinal astrocytoma or hamartoma
Mental retardation

Lisch nodules (iris hamartoma)
Osseous lesions (present by age 1): sphenoid dysplasia or thinning of long bone cortex
Scoliosis
Hypertension
Learning problems

CNS = central nervous system.

Note: Diagnosis of neurofibromatosis type 1 requires two of the following seven clinical findings: six or more café-au-lait spots (≥ 5 mm in children or 15 mm in adults); two or more neurofibromas or one plexiform neurofibroma; freckling in axilla or groin; optic glioma; two or more Lisch nodules; characteristic osseous lesion; first-degree relative with neurofibromatosis type 1.

*Neurofibromatosis type 2 accounts for 10% of all cases of neurofibromatosis and is characterized by bilateral acoustic neuromas. Skin findings of café-au-lait spots and neurofibromas are less common findings as compared with neurofibromatosis type 1.

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  1. Nevocellular nevi

are pigmented lesions that may be congenital or acquired.

  1. Congenital nevi.These black, brown, tan, or flesh-colored papules or plaques are first detected between birth and 6 months of age. They occur in 1–2% of neonates. All congenital nevi may have an increased risk of malignancy, but giant nevi (> 20 cm in diameter) have a 6–7% lifetime risk of development of malignant melanoma. Management of giant nevi often includes excision, if possible, and careful observation of all other congenital nevi.
  2. Acquired nevi(moles). Peak ages of development are 2–3 years and 11–18 years. Moles are characterized as well-demarcated brown or black papules that increase in size and number during puberty or pregnancy and after sunburn. Most acquired nevi in childhood are junctional nevi. The risk of malignant transformation is lower than for congenital nevi. Management is careful observation.

VII. Disorders of the Hair

  1. Alopecia Areata
  2. Etiology.The cause is thought to be autoimmune lymphocyte-mediated injury to the hair follicle.
  3. Epidemiology.Alopecia areata affects 1 in 1, 000 persons.
  4. Clinical features
  5. Complete hair lossoccurs in one to three sharply demarcated scalp areas without any scalp inflammation. The hair loss is described as occurring suddenly, and the underlying skin is smooth and soft.
  6. Pitting of the nails occurs in 40% of patients.
  7. Subtypes of alopecia areata include alopecia totalis(loss of all scalp hair) and alopecia universalis (loss of all body and scalp hair).
  8. Management.Most patients have regrowth of hair within 1 year without any treatment. Accelerated hair growth may occur with topical or injected corticosteroids and topical minoxidil. Wigs and counseling may be necessary because of the psychological consequences of the significant hair loss.
  9. Tinea capitis

is a common cause of hair loss (see section V.A.2).

  1. Traumatic alopecia

is also a common cause of childhood hair loss and may be one of two types:

  1. Trichotillomaniais hair loss that occurs as a result of conscious or unconscious pulling or twisting of hair. Clinical features include irregularly bordered areas of hair loss in which hairs are broken off at different lengths. Scalp may show perifollicular petechiae and excoriations. Eyelashes and eyebrows may also be involved. The cause is unknown, although it may be associated with anxiety. Management includes stress relief, a search for precipitating events, and application of oils to make the hairs more difficult to pull out.
  2. Traction alopeciais hair loss caused by constant traction or friction and may be the result of tight hair braids or curlers, vigorous scalp massage, or constant rubbing. Clinical features include patchy areas of alopecia

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with thinned, small hairs, but with few broken hairs. Management is to stop the inciting trauma.

  1. Telogen effluvium

is the second most common type of alopecia, after male pattern baldness. It is caused by any acutely stressful event (e.g., pregnancy, surgery, acute illness, trauma) that converts hairs from a growing phase (anagen) to a final resting phase (telogen). Clinical features include complaints of generalized excessive hair loss (hair loss > 100 hairs per day; normal hair loss is 50–100 hairs per day) 2–3 months after the precipitating event. Hair loss continues for 3–4 months, and then spontaneous regrowth occurs.

  1. Other conditions that cause

hair loss include hypothyroidism, diabetes mellitus, hypopituitarism, nutrition disorders (e.g., hypervitaminosis A, zinc deficiency, marasmus), medications (e.g., warfarin, heparin, chemotherapy, cyclophosphamide), ectodermal dysplasia, and hair shaft structural defects.

VIII. Acne Vulgaris

Acne is the most common skin disease, and its sequelae may include scarring and disfigurement and adverse effects on psychosocial development, such as depression and other emotional problems.

  1. Pathophysiology

Acne is caused by a combination of the following processes:

  1. Excessive shedding and cohesion of cells that line the sebaceous follicles located on the chest, back, and face
  2. Production of sebumby sebaceous glands under the influence of androgens. Obstruction of sebum outflow from the follicle leads to the formation of comedones.
  3. Inflammation as a result of the proliferation of the bacteriaPropionibacterium acnes.
  4. Clinical Features
  5. Acne begins 1–2 years before puberty.
  6. Noninflammatory acneis characterized by open comedones (blackheads) and closed comedones (whiteheads).
  7. Inflammatory acneis characterized by erythematous papules, pustules, nodules, and cysts.
  8. Most patients have a combination of inflammatory and noninflammatory acne.
  9. Management

Treatment is individualized based on the disease severity and on the location and type of lesions.

  1. Topical benzoyl peroxide, tretinoin (Retin-A), and salicylic acid are effective for noninflammatory acne and mild inflammatory acne.
  2. Antibiotics (oral or topical) and benzoyl peroxide are effective for inflammatory acne.
  3. Systemic isotretinoin (Accutane)is highly effective for all types of acne, including nodular and cystic acne. Women must be tested for pregnancy before treatment and must use effective birth control during treatment to prevent pregnancy because of the risk of teratogenic effects associated with its use.

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Review Questions and Answers

  1. A 1-week-old female infant has several vesicles on her scalp. She also has a 1-day history of fever to 100.8°F (38.2°C) and irritability. She is breastfed and is eating slightly less vigorously than usual. The mother's pregnancy was uncomplicated. Which of the following statements regarding the presumptive diagnosis is correct%

(A) Herpes simplex virus type 1 is the most likely causative pathogen.

(B) The infection was likely acquired after birth.

(C) A Tzanck smear of the base of one of the vesicles may demonstrate epidermal giant cells.

(D) Oral acyclovir should be started immediately.

(E) Oral antibiotics to cover staphylococcal and streptococcal infection should be started promptly.

  1. A 9-year-old girl is brought the office by her parents. She has a 1-month history of two large well-demarcated areas of hair loss in the parietal scalp. On examination, no inflammation of the skin is apparent, and the underlying skin is smooth and soft. Which of the following statements regarding the likely diagnosis is correct%

(A) The fingernails are likely to be normal.

(B) Stress is not a likely cause of the disorder.

(C) Oral griseofulvin should be prescribed after cultures.

(D) Zinc should be prescribed for suspected zinc deficiency.

(E) The hair loss is likely to be permanent.

  1. A 6-year-old boy presents with a 1-month history of patchy alopecia in the occipital region of the scalp. Examination reveals a well-circumscribed area of hair loss in which all the hairs appear to be broken off at the scalp surface. Occipital lymph nodes are prominent. Which of the following statements regarding the likely diagnosis is correct%

(A) This infection is contagious, and brushes, combs, and hats should not be shared.

(B) Topical management with clotrimazole is the initial appropriate treatment.

(C) Exposure to dogs or cats is the likely cause of infection.

(D) Hairs will likely fluoresce under Woods light examination.

(E) Oral antifungal therapy should be administered for 2 weeks.

  1. A 5-year-old boy presents with a 6-week history of scaling, nongreasy papules and plaques in the occipital region of the scalp and in the inguinal region. The lesions have a “silvery scale” appearance. Which of the following statements regarding the likely disorder is correct%

(A) Low-potency corticosteroids are indicated.

(B) It would be unusual for other family members to also have this disorder.

(C) New lesions would be expected to develop at any site of skin trauma.

(D) Hair loss is associated with scalp involvement.

(E) Arthritis is expected.

  1. A 10-year-old girl presents with a history of malaise and a headache that was followed 4 days later with a body rash. Examination reveals a 3-cm scaly erythematous plaque on the upper arm and oval, red macules and papules on the back that follow skin lines. Which of the following management steps is most appropriate%

(A) Low-potency topical corticosteroids

(B) Moderate- to high-potency topical corticosteroids

(C) Topical clotrimazole

(D) Oral antibiotics

(E) Reassurance only

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  1. A 4-month-old male infant is brought to the office by his parents for a routine health maintenance examination. On examination, you note significant hyperpigmentation in the inguinal area. Medical history is remarkable for suspected diaper dermatitis treated with zinc oxide and high-potency corticosteroids for 3 weeks. Which of the following statements regarding this patient and his clinical findings is most correct%

(A) Topical antifungal therapy should now be prescribed to treat suspected fungal superinfection.

(B) Zinc oxide should be immediately discontinued.

(C) Atrophy of skin in the inguinal area may also be present.

(D) The hyperpigmentation is not associated with any systemic problems.

(E) Ultraviolet light therapy should be prescribed.

  1. A 4-year-old boy with a history of atopic dermatitis presents for evaluation of his skin. Examination shows that the skin on his upper and lower extremities is very dry and irritated. You would like to suggest a moisturizer in addition to topical corticosteroids. Which of the following types of moisturizers is most appropriate%

(A) Lotion

(B) Cream

(C) Ointment

(D) Solution

(E) Gel

  1. A 13-year-old boy is brought to the office by his parents because of concerns regarding his acne. Examination reveals scattered open and closed comedones on the forehead and nose. Which of the following statements regarding this condition is correct%

(A) Topical benzoyl peroxide is an appropriate first-line treatment.

(B) Oral isotretinoin is an appropriate first-line treatment.

(C) Oral clindamycin is an appropriate first-line treatment.

(D) Sebum plays little role in the pathophysiology at this stage.

(E) Reassurance only should be given because the patient's skin findings are currently of little consequence.

For statements 9–13, the response options are the same. You will be required to select one answer for each statement in the set.

Match the disorder with its most characteristic skin lesion.

  1. A 3-year-old boy with herpes simplex virus infection involving the upper and lower lips.

(A) Papule

(B) Macule

(C) Pustule

(D) Nodule

(E) Vesicle

(F) Cyst

(G) Wheal

(H) Target lesion

(I) Plaque

  1. A 7-year-old boy with suspected vitiligo involving both hands.

(A) Papule

(B) Macule

(C) Pustule

(D) Nodule

(E) Vesicle

(F) Cyst

(G) Wheal

(H) Target lesion

(I) Plaque

  1. A 15-month-old girl with molluscum contagiosum on the cheeks and forehead.

(A) Papule

(B) Macule

(C) Pustule

(D) Nodule

(E) Vesicle

(F) Cyst

(G) Wheal

(H) Target lesion

(I) Plaque

  1. A 6-year-old boy with erythema multiforme major.

(A) Papule

(B) Macule

(C) Pustule

(D) Nodule

(E) Vesicle

(F) Cyst

(G) Wheal

(H) Target lesion

(I) Plaque

  1. A 10-year-old girl with suspected Gianotti-Crosti syndrome.

For statements 14 and 15, the response options are the same. You will be required to select one answer for each statement in the set.

(A) Neurofibromatosis type 1

(B) Neurofibromatosis type 2

(C) Tuberous sclerosis

For each patient, select the most likely associated neurocutaneous syndrome.

  1. A 3-year-old boy with seizures and Lisch nodules on ophthalmologic examination.
  2. A 12-month-old infant with infantile spasms.

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Answers and Explanations

  1. The answer is C[V.C.7.c, d]. This patient's clinical presentation is most consistent with neonatal herpes simplex virus (HSV) infection. Diagnosis is by identification of (1) the virus by culture or (2) the viral antigen by rapid testing techniques. Infection may also be diagnosed by identification of epidermal giant cells on a Tzanck preparation. Two thirds of herpes simplex infections acquired during the neonatal period are caused by HSV-2, and this infection is most often acquired during passage through the birth canal of a mother infected with the virus. Neonatal HSV is a medical emergency that requires prompt admission and management with intravenous acyclovir. Oral antibiotics are not useful.
  2. The answer is B[VII.A]. This patient's presentation with well-demarcated hair loss without scalp inflammation is likely caused by alopecia areata. The cause of alopecia areata is thought to be an autoimmune lymphocyte-mediated injury to the hair follicle. Stress is not likely to cause this form of alopecia. Associated findings include nail pitting in 40% of patients. The clinical presentation is neither consistent with tinea capitis nor zinc deficiency; therefore, neither griseofulvin nor zinc is indicated. Regrowth of hair within 1 year occurs in the majority of patients.
  3. The answer is A[V.A.2.a]. Clinical features of alopecia with hairs broken off at the scalp and occipital lymphadenopathy suggest tinea capitis, a fungal infection of the hair. The most common causal pathogen is Trichophyton tonsurans, acquired from human-to-human contact, including by sharing hats, brushes, and combs. Topical antifungal therapy is ineffective for tinea capitis. Dogs and cats are a source of infection with Microsporum canis, which currently causes only 5% of tinea capitis infections. Infection with M. canisis characterized by thickened, white broken hairs, and only hairs infected with M. canis fluoresce under Woods light. Treatment of tinea capitis involves 6–8 weeks of oral antifungal therapy.
  4. The answer is C[III.E.3]. Skin lesions with a silvery scale appearance suggest psoriasis. Lesions of psoriasis may also demonstrate the Koebner phenomenon, in which new lesions develop at sites of skin injury. Corticosteroids must be moderate or high potency to be effective as treatment agents. Psoriasis is inherited in an autosomal dominant fashion, and therefore other family members may also have the disorder. Involvement of the scalp is common; however, associated alopecia is uncommon. Arthritis is uncommon during childhood.
  5. The answer is E[III.D.3, 4]. This patient's clinical presentation and examination findings are consistent with pityriasis rosea. Pityriasis rosea may be a hypersensitivity reaction to a viral infection, although its true cause is unknown. Pityriasis rosea resolves without medications, although antihistamines may relieve any associated itching.
  6. The answer is C[I.D.6.a]. The hyperpigmentation in the inguinal region is most likely a side effect of the high-potency corticosteroid therapy. Only low-potency corticosteroids should be applied to the groin because of the thinness of the epidermis of the groin; absorption of corticosteroids is greater in this area. Systemic side effects may occur, including growth suppression, Cushing syndrome, and adrenal suppression. Local side effects include pigmentation changes, atrophy, acne, folliculitis, and telangiectasias. Neither antifungal medications nor ultraviolet light is indicated. Discontinuation of zinc oxide will not affect this patient's skin findings.
  7. The answer is C[I.D.2]. Adequate hydration of the skin is crucial in many dermatologic conditions, especially atopic dermatitis. Ointments are especially useful for very dry skin because they have maximal water-retaining properties and would be the best choice for this patient. Lotions are helpful for minimal dryness, and creams are useful for average dryness. Both solutions and gels are most useful for surfaces with hair.
  8. The answer is A[VIII.C]. This patient's skin findings are consistent with acne. The open and closed comedones are characteristic of noninflammatory acne, and a topical agent is most appropriate. Benzoyl peroxide is very effective for both noninflammatory and inflammatory acne and is the most appropriate initial treatment for this patient. Neither oral antibiotics nor isotretinoin is a first-line treatment for noninflammatory acne. Oral antibiotics are most useful in inflammatory acne. Systemic isotretinoin is helpful in all types of acne; however, it is most beneficial in severe cystic or nodular acne. Obstruction to sebum outflow from the follicle leads to comedone development and therefore is important in the pathophysiology. Acne should never be dismissed as of no consequence, even in the early stages, because it may be associated with future scarring and may have effects on a child's psychosocial development.

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9–13. The answers are E, B, A, H, and A, respectively [V.C.7.b, VI.A.3, V.C.10.b.(1), IV.C.2, V.C.5, Table 19-1]. Herpes simplex virus is characterized by grouped vesicles on an erythematous base. Vitiligo is a depigmentation disorder characterized by hypopigmented macules. Molluscum contagiosum is characterized by flesh-colored papules with central umbilication. Erythema multiforme major is characterized by target lesions. Red or flesh-colored papules are characteristic of Gianotti-Crosti syndrome.

14–15. The answers are A and C, respectively [Table 19-3]. The 3-year-old boy has neurofibromatosis type 1, which is characterized by café-au-lait spots, axillary freckling, and neurofibromas in the skin and other organs. Seizures may occur because of central nervous system involvement that may include intracranial calcifications, neurofibromas, and optic glioma. Characteristic eye findings include Lisch nodules or iris hamartomas. The 12-month-old infant has tuberous sclerosis, which is associated with characteristic skin findings including ash-leaf spots, angiofibromas, and Shagreen patch. Almost all children with tuberous sclerosis have seizures, including infantile spasms, because of central nervous system involvement.