Case Based Pediatrics For Medical Students and Residents
Department of Pediatrics, University of Hawaii John A. Burns School of Medicine
Chapter XXI.6. Common Skin Conditions
Annemarie Uliasz
February 2003

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This is a 6 month old female who is brought to the office with her mother with a chief complaint of a diaper rash for one week. Mother has been using baby powder to keep the area dry, but the rash is worsening.

Upon examination, the buttocks, perianal region, and tops of the thighs appear erythematous with no ulcerations or erosions. Areas of flexure are involved and there are some beefy red areas with a few satellite lesions. The rest of the exam is normal.

Her mother is given instructions to change her infant's diapers frequently, at least every three hours. Baby powder does not keep the area dry once the child urinates, so its value is minimal. Special attention should be made to keep the skin under the diapers dry. Hydrocortisone ointment or cream can be used to suppress the inflammation. Petrolatum or zinc oxide applied to the diaper region is suggested as prophylaxis against irritation. Topical clotrimazole cream is also recommended to eliminate any yeast infection that may be present.


The skin is composed of three different layers. The outer most layer, the epidermis, is made predominantly of keratinocytes. The most superficial layer of the epidermis, the stratum corneum, serves as a protective barrier against the environment, and prevents desiccation. The epidermis also plays a role in immune surveillance (1). Damage to the epidermis increases skin permeability, thereby increasing the risk of infection. The epidermis also contains melanocytes (which gives the skin its color), Merkel cells (which are pressure receptors), and Langerhans cells (which participate in the skin's immune response).

The dermis lies beneath the basement membrane of the epidermis. The dermis consists of collagen, elastin, and proteoglycans, which lend support and durability to the skin. Blood vessels, lymphatics, sweat glands, hair follicles, smooth muscle, and neuroreceptors are all found in the dermis. Fibroblasts in the dermis are responsible for collagen production and are the predominant cell in this layer of the skin. Other cells common in the dermis include mast cells, leukocytes, and histiocytes.

Subcutaneous tissue resides beneath the dermis. This layer serves as insulation, a fat depot, and a cushion against trauma. Blood vessels and lymphatics are found in the subcutaneous tissue as well as the base of hair follicles and sweat glands.

In order to describe a skin lesion, one must have a basic understanding of the language of dermatology. A primary lesion is a lesion that has not been altered by trauma, infection, scratching, therapy, or regression over time. Primary lesions are described as macules, patches, papules, nodules, tumors, vesicles, bullae, pustules, plaques, cysts, and wheals. A macule is a flat, circumscribed skin discoloration that is neither raised nor depressed. It cannot be felt. Once it reaches 1cm or greater in size, it is termed a patch. A papule is an elevated, solid lesion that is less than 0.5cm in diameter. If the diameter is greater than 0.5cm, it is known as a nodule. A nodule is basically a larger, deeper papule. Tumors are usually larger in diameter than nodules, and tend to be variable in consistency and mobility. Vesicles (blisters) are raised, fluid-filled lesions less than 0.5cm in diameter. A bulla is a larger fluid-filled lesion that is greater than 0.5cm in diameter. A pustule is a papule that contains purulent material. A plaque is an aggregation of papules, vesicles, or pustules that is greater than 0.5cm in diameter. Wheals are palpable, firm, edematous lesions that may vary in configuration and size. They tend to be pruritic and evanescent (existing briefly before disappearing). A cyst is a lesion that contains fluid or semi-solid material. Its walls are circumscribed and thick, and it is located deep in the skin.

Primary lesions may develop or turn into secondary lesions. Secondary lesions include crusts, scales, excoriations, fissures, erosions, ulcers, and scars. Crusts (scabs) are dried collections of blood, serum, or pus. They usually arise from a primary lesion such as a vesicle, bulla, or pustule. Scales consist of compressed layers of keratinocytes on the skin surface. An excoriation is a linear erosion caused by scratching. A fissure is a crack in the skin. An erosion is a focal loss of epidermis that heals without scarring. An ulcer is a focal loss of epidermis extending into the dermis that heals with scarring. A scar is an end-stage lesion composed of connective tissue, which may be atrophic or hypertrophic.

Once the definitions of primary and secondary lesions are learned, a skin lesion may be described. The description should include the lesion's size, color, shape, arrangement, distribution, and whether it is a primary or secondary lesion. The following chapter discusses common dermatologic conditions in the pediatric patient.

Contact dermatitis can result from injury to the skin, as in irritant dermatitis, or from a hypersensitivity response, as in allergic dermatitis. The distribution of the rash is determined by the points of contacts. Common hypersensitivity contact dermatitis allergens include latex (rubber), nickel (jewelry, buckles, snaps), hair dye and leather (tanning chemicals). If a particular substance is suspected, a simple test to confirm hypersensitivity is to tape a small piece of it on the medial portion of the upper arm and observe for a reaction 12 hours later.

In the pediatric population, irritant dermatitis is more commonly seen than allergic dermatitis. Irritant dermatitis is an inflammation of the skin caused by exposure to irritants such as soaps, saliva, citrus juice, bubble baths, or detergents (1). The appearance of the skin may range from mild redness, edema, or vesicles to oozing bullae. The face and hands may be affected by saliva from a drooling infant. Bubble baths may be the source of an intense pruritus. Restrictive shoes that trap sweat and moisture may cause irritant dermatitis of the feet. Treatment of contact dermatitis may be as simple as removing the irritant. Hydrocortisone cream will provide additional relief.

Diaper dermatitis (diaper rash) is a common ailment of infants. Diaper rash occurs in approximately 50% of infants. The peak of incidence occurs between the ages of nine and twelve months (2). The main source of irritation is urine and feces on the skin. Diaper dermatitis may occur if diapers are not changed frequently enough, or if the infant has diarrhea. However, it may occur even if diapers are changed regularly. The buttocks, perineal area, lower abdomen and top of the thighs are the areas that are most frequently involved. Characteristically, areas of flexure are spared. The rash appears erythematous, and the skin may look scalded. Ulcers and erosions may be seen in severe cases. Diaper rash may be treated by frequent changes of diapers, at least every three hours, and close attention to keeping the skin dry. Most cases are self-limited and resolve in 3 days (3). Petrolatum or zinc oxide may be used as a protective barrier. Severe cases may be treated with low potency topical corticosteroids. Diaper rashes may be complicated with a secondary Candida infection. Candida albicans can complicate any diaper rash that has been present for three or more days (4). In these cases, the rash involves the skin flexures with satellite lesions. These rashes may be treated with anti-candidal agents (e.g., clotrimazole, miconazole and nystatin).

Erythema toxicum, a skin eruption which occurs in roughly half of all newborns, usually within the first two days of life (5). It is self-limited, lasting approximately three days. The etiology is unknown. Erythema toxicum presents as papules, macules, and sometimes pustules surrounded by an irregular halo of erythema. The lesions are distributed on the arms, legs and trunk. A Wright stain of a smear (by pricking the skin and doing a touch prep on a slide) reveals eosinophils with no organisms present (3).

Nevi (moles) are clusters of melanocytes that appear at the epidermal-dermal junction. The number of acquired nevi increases with age, reaching a plateau in the 30s or 40s (1). An adult will have on average 25-30 nevi. The amount of nevi that develop is related to the amount of sun exposure sustained in childhood. Although most nevi are benign, a small percentage may undergo malignant transformation into melanoma. Risk of melanoma increases as the number of nevi increases and as the amount of sun exposure increases. Malignant change may be suspected if the nevi display irregular borders, large size (5-15mm), multiple colors, or become ulcerated, scaled, or indurated. If any of these suspicious characteristics are observed, the nevus can easily be excised. A complete skin examination is recommended for children with atypical nevi. These children should be counseled regarding limiting sun exposure.

Paronychia is inflammation of the nail folds of the fingers. Acute paronychia may occur spontaneously, or after trauma, removal of a hangnail, or nail-biting (6). Staphylococci or streptococci infections are often responsible for acute paronychia. The patient presents with warmth, edema, erythema and proximal nail fold tenderness. Treatment includes warm soaks (to soften the skin), oral antibiotics, and drainage of an abscess if one is present. The chronic form is more commonly seen in children and is often caused by finger sucking, which creates a desirable environment for yeast, such as Candida, and bacteria to thrive (7). In chronic paronychia, the nail fold (eponychium) will swell and then separate from the underlying nail plate. Foreign material present under the nail leads to inflammation and infection. Treatment includes reducing predisposing factors, careful attention to hand drying, incision and drainage of the pus, and topical anti-inflammatory agents. Antibiotics may be employed empirically or until the cultures come back (most likely Staph aureus) (7).

Varicella zoster (chickenpox) is spread via respiratory secretions and direct contact with cutaneous lesions. Routine varicella immunization has drastically reduced the incidence of this infection. The incubation period is approximately 2 weeks (10 to 21 days). Subsequently, a pruritic, vesicular rash originates on the scalp or trunk and spreads to the rest of the body. Macular or papular lesions appear which develop into vesicles. The lesions of varicella zoster are sometimes described as "dew drops on a rose petal" (8). The vesicles then dry up and become crusts, which persist for three weeks before disappearing. Typically, there are lesions in various stages of healing. Children are contagious from two days before to five days after the onset of the rash. A Tzanck smear may be helpful in confirming the diagnosis (reveals multinucleated giant cells) (6), but this is usually unnecessary. Complications include secondary infection with staphylococci or streptococci. Varicella encephalitis may occur shortly after the appearance of the rash, most commonly presenting with mild ataxia. However, the prognosis is usually good, unlike the encephalitis caused by herpes simplex virus. Immunocompromised patients with varicella zoster infections may experience persistent vesicular eruptions that may become hemorrhagic or they may experience disseminated varicella. It is recommended that high-risk individuals (immunocompromised) receive human varicella zoster immunoglobulin (VZIG) following exposure to chickenpox. Additionally, neonates whose mothers develop chickenpox within five days prior to or two days following delivery should receive VZIG as well as premature neonates born less than 30 weeks gestation who have been exposed to chickenpox. Acyclovir may be administered in cases of severe varicella, but some advocate routine use of acyclovir for varicella or zoster, especially for adolescents due to their propensity to develop severe disease. Because of the risk of Reye syndrome, aspirin should be avoided.

Once chickenpox subsides, the virus becomes latent. Latent varicella may reactivate causing herpes zoster. Herpes zoster, or shingles, is characterized by groups of vesicles distributed along a cutaneous nerve (a dermatome). The thorax is most commonly involved, but lesions may appear along any dermatome. Involvement of the face, neck, and eye can be serious. New crops of vesicles may appear for three to five days. As in chickenpox, the vesicles dry up into crusts and disappear within three weeks.

Five to ten percent of children develop cutaneous warts (1). Common warts, typically found on the hands, are caused by HPV (human papilloma virus) types 1, 2, 4, and 7 (9). Common warts are flesh-colored, rough, and hyperkeratotic. When the superficial surface is excised, many black dots may be visible. These black dots are actually loops of capillaries. Plantar warts are found on the soles of the foot. They are often compressed against the surface of the foot due to continual weight bearing pressure and may be painful. Plantar warts are caused by HPV types 1and 2. Flat warts, or verrucae planae, are caused by HPV types 3 and 11. They are slightly raised, typically less than 3mm in diameter, and appear in crops of 10-30 or more. Their color ranges from pink to brown, and may occur on the forehead and dorsum of the hand. Condyloma acuminata are warts that are found in the anogenital region. They are most commonly seen in the sexually active adolescents. In a young child, these warts may have been transmitted through the birth canal, through spread from cutaneous warts, or they may signify child abuse. Condyloma acuminata are caused by HPV types 6, 11, 16, 18, and 31. Types 16, 18, and 31 are associated with cervical cancer. Condyloma acuminata are moist, soft, papillomatous lesions that may occur as single or multiple lesions. If untreated, they may grow to cauliflower-like masses. Genital warts are covered in the chapter on sexually transmitted infections.

Over fifty percent of warts regress spontaneously within two years. However, untreated warts have the potential to spread and progress. When treating warts, it is imperative to protect the surrounding skin from irritation. Prior to treatment, plantar, palmar, and common warts should be pared down until the capillaries are revealed. This makes the warts more responsive to treatment. It is recommended that therapy be administered every two weeks. Liquid nitrogen or cantharidin may be used to treat common warts as well as light electrodesiccation and curettage. Common warts and plantar warts may respond to lactic acid or salicylic acid treatments (over the counter topical wart medication). These warts may also be soaked in warm water and reduced with a pumice stone. Successful treatment with duct tape has also been reported. Condyloma may be treated with podophyllin applications every two weeks. However, if the warts are refractory, liquid nitrogen or CO2 laser treatment may be necessary.

Molluscum contagiosum is a viral infection of the skin caused by a DNA containing pox virus. It is most commonly seen in children. Boys are more commonly affected than girls are. The peak incidence is at age ten years (2). The lesions are small, firm, skin-colored papules that are centrally umbilicated. They may appear as one or multiple lesions, and tend to be approximately 1-5 mm in diameter. The papules may occur anywhere on the body, but are usually found on the trunk, face, arms, and genital region. Molluscum contagiosum may be spread by direct contact, or by autoinoculation. This infection typically spontaneously resolves within six to nine months, however, treatment may prevent autoinoculation and person to person spread (1). Treatment includes curettement, electrosurgery, cryosurgery, or other standard wart medications. Instructions on washing it well (to prevent spread) may be all that is necessary.

Pediculosis, commonly known as lice, affects people of all ages. There are three types of lice: body or clothing lice (Pediculus humanus corporis), head lice (Pediculus humanus capitis), and pubic or crab lice (Phthirus pubis). Pruritus is the hallmark of all types of pediculosis. Lice bite the skin and live on the blood. They cannot survive without human contact. The female louse lays eggs, which may be seen attached to hair follicles or clothing fibers. Once the eggs hatch, the newly born lice mature in 30 days (1). The female louse lives another thirty days and deposits a few eggs each day. The diagnosis is made by identifying lice or eggs (nits) on the hair shaft or clothing fibers. The nits are small white oval-shaped capsules.

Body lice is rare in children. It may be seen in conditions of poor hygiene, especially in colder environments when the opportunity to change clothes regularly is lacking. The lice are transmitted on contaminated clothing or bedding. They are found on the skin only transiently when they are feeding. At other times, the nits are firmly attached to the seams of clothing. The primary lesion found on the shoulders, trunk or buttocks, is a small, red macule or papule with a central hemorrhagic punctum. Treatment consists of improved hygiene and washing all infested clothing and bedding in hot water. Alternatively, the lice will starve if clothing is stored at 75-85 degrees F for two weeks. For those unable to change clothes, clothes may be dusted with 10% lindane powder. Lindane lotion or permethrin cream may be applied for 8-12 hours to eradicate eggs and lice on body hair.

Head lice infest the scalp hair. It is especially bothersome among school children. Patients often present with scalp itching. If the eyelashes are involved, conjunctivitis may result. Transmission occurs by head-to-head contact, and shared combs, brushes, or towels. Translucent eggs are laid near the proximal portion of the hair shaft. Treatment involves application of 0.5% malathion (Ovide) to the hair for 12 hours (although application for much shorter periods may be sufficient). The hair is then washed, and the dead nits are then removed from the hair shafts by a fine toothed comb. Clothes must be laundered or dry-cleaned. Other shampoo treatments include permethrin 1% creme rinse (Nix or Elimite), pyrethrin shampoo, or 1% lindane shampoo (Kwell). Lindane is potentially neurotoxic so it is not recommended for infants and young children. These shampoos are applied and rinsed after 10 minutes, with a repeat application 7-10 days later. There are presently no published trials assessing the safety or efficacy of alternative treatments such as herbal remedies, kerosene, or battery-powered combs. Occlusive dressings are sometimes recommended using mayonnaise or petroleum jelly, but their efficacy is not thoroughly studied.

Pubic lice (crabs) is transmitted by skin-to-skin or sexual contact with an infested individual. The infestation is usually encountered in adolescents, although small children may occasionally acquire pubic lice on the eyelashes. Pubic lice are only 1-2 mm in length (body and head lice are 2-4 mm in length), and are greater in width than length, giving them a crab-like appearance. Treatment includes a 10 minute application of a pyrethrin preparation. Retreatment may be necessary in 7-10 days. Lindane shampoo, which requires a 10 minute application time, is an alternative choice. Eyelash involvement may be treated by petrolatum applied three to five times per day for 8-10 days. Clothing, bedding, and towels should be thoroughly washed or dry-cleaned.

Scabies is caused by the female Sarcoptes scabiei mite. A papular and vesicular rash is seen as a result of the mite burrowing into the stratum corneum. The mites burrow approximately 2mm (1). Itching occurs two to six weeks after infestation, and may be more intense at night when the mites are more active. Lesions are most commonly seen between the fingers and toes, axillae, flexor surfaces of the wrists, belt line, and areas surrounding the nipples, genitals, and buttocks. A diagnosis of scabies is made based on a history of itching and the characteristic lesions. A definitive diagnosis is made upon identification of the adult mite, ova, or larvae upon microscopic examination of skin scrapings from the lesions, but this is rarely done in general pediatric practice. The patient should bathe thoroughly and the involved areas should be scrubbed with a brush. Permethrin cream (Elimite), lindane lotion (Kwell), or crotamiton (Eurax) lotion may be applied, and the patient should be dressed in clean clothing. Bedding should be cleaned and other family members should be questioned and inspected to determine if they are infested as well. Scabies may persist for months in patients who are untreated.

Mosquito bites and flea bites are common sources of skin irritation in children. Fleas tend to bite multiple times in one area, whereas mosquitoes usually bite in random widely dispersed areas that are not covered by clothes. The irritation that stems from an insect bite is due to a localized hypersensitivity reaction. Treatment of mosquito and flea bites consists of cool compresses, calamine lotion, topical hydrocortisone and oral antihistamines to provide relief from the pruritus. Insect repellants may be used on exposed skin as prophylaxis. DEET containing mosquito repellants are effective, but DEET is potentially neurotoxic so it should be applied judiciously. Using clothes to completely cover the skin may be safer. Fleas may be eradicated by treating pets and decontaminating the house.


Questions

1. Name the three layers of skin. Name three functions of skin.

2. What organism is responsible for the development of warts?

3. What are the two organisms responsible for infection in acute paronychia?

4. What is the treatment for lice?

5. Who should receive varicella zoster immunoglobulin?

6. What characteristics of a mole are suspicious for malignant melanoma?


References

1. Darmstadt GL. The Skin. In: Berman RE, et al (eds). Nelson Textbook of Pediatrics, sixteenth edition. 2000, Philadelphia: W.B. Saunders Company, pp. 1965-2054.

2. Frieden IJ. Diaper Dermatitis. In: Arndt KA, Wintroub BU, et al (eds). Primary Care Dermatology. 1997, Philadelphia: W.B. Saunders Company, pp. 82-84.

3. Freedberg IM, Sanchez MR (eds). Current Dermatologic Diagnosis and Treatment. 2001, Philadelphia: Lippincott Williams and Wilkins, pp. 48-49, 122-123.

4. Morelli JG. Pediatric Dermatology. In: Fitzpatrick JE, Aeling JL (eds). Dermatologic Secrets. 1996, Philadelphia: Hanley & Belfus, Inc., pp. 355.

5. Clemons RM. Issues in newborn care. Prim Care 2000;27(1):251-267.

6. Goodheart HP. A Photoguide of Common Skin Disorders Diagnosis and Management. 1999, Baltimore: Williams and Wilkins, pp. 106-109, 190-191.

7. Gerondale BJ. Nail Disorders. In: Fitzpatrick JE, Aeling JL (eds). Dermatologic Secrets. 1996, Philadelphia: Hanley & Belfus, Inc., pp. 404.

8. Brice SL. Bullous Viral Eruptions. In: Fitzpatrick JE, Aeling JL (eds). Dermatologic Secrets. 1996, Philadelphia: Hanley & Belfus, Inc., pp. 162-165.

9. Reed BR. Warts (Human Papillomavirus Infections). In: Fitzpatrick JE, Aeling JL (eds). Dermatologic Secrets. 1996, Philadelphia: Hanley & Belfus, Inc., pp. 167-173.


Answers to questions

1. The three layers of skin are the epidermis, dermis, and subcutaneous tissue. The skin serves as a barrier against the environment, protection against desiccation, and plays a role in immune surveillance.

2. Human papilloma virus is organism responsible for the development of warts.

3. Staph aureus is responsible for most infections in acute paronychia.

4. Pediculosis is treated with a shampoo such as 0.5% malathion rinse, permethrin 1% creme rinse, 1% lindane shampoo, or pyrethrin. After the shampoo is rinsed, the hair is combed with a fine toothed comb to remove dead nits. Clothes and bedding must be washed in hot water.

5. Varicella immunoglobulin should be given to immunocompromised individuals, neonates whose mothers develop chickenpox within five days prior to or two days following delivery, and premature neonates born less than 30 weeks gestation who have been exposed to chickenpox.

6. Suspicion of malignant transformation of nevi should arise upon observation of irregular borders, variegated color (multiple colors), size greater than 5-15 mm, and any change in texture including crusting, ulceration, or induration.


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