Daniel A. Handel
HERPES ZOSTER INFECTION
CLINICAL FEATURES
Herpes zoster results from activation of latent varicella zoster virus.
Pain or dysesthesia precedes the eruption by 3 to 5 days.
Eruptions can occur anywhere on the body. Thoracic dermatomes are involved in greater than 50% of cases, cranial or trigeminal regions in 20%, lumbar 15%, and sacral 5%.
Erythematous papules progress to clusters of vesicles with an erythematous base.
Lesions involving the nose should lead to significant concern for ophthalmic involvement and development of keratitis, which can lead to blindness.
DIAGNOSIS AND DIFFERENTIAL
A Tzanck prep and viral culture can confirm a diagnosis typically made on history and physical examination.
The differential diagnosis includes herpes simplex, erysipelas, impetigo, and contact dermatitis.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Antivirals such as acyclovir, famciclovir, or valacyclovir are beneficial if administered within 24 to 72 hours after the eruption of the lesions.
Aluminum acetate solution or petroleum jelly compresses provide symptomatic treatment.
TINEA INFECTIONS
CLINICAL FEATURES
Tinea pedis is a fungal infection of the feet, also known as athlete’s foot.
Tinea manuum, a dermatophyte infection of the hand, is often unilateral and frequently associated with tinea pedis.
The most common form of tinea pedis is the interdigital presentation, manifested by maceration and scaling in the web spaces between the toes. Ulcerations may be present in severe cases with secondary infection.
The second type of tinea pedis is characterized by chronic, dry scaling with minimal inflammation on the palmar or plantar surfaces. It often extends to the medial and lateral aspects of the feet, but not the dorsal surface. Maceration between the toes is common.
The third type of fungal infection (bullous tinea pedis) presents as an acute, painful, pruritic vesicular eruption on the palms or soles. Erythema is a prominent feature, while the nails and web spaces are usually spared.
Tinea cruris, a fungal infection of the groin commonly called jock itch, is very common in males. Erythema with a peripheral annular, scaly edge is seen. The rash extends onto the inner thighs and the buttocks and spares the penis and scrotum—a feature that is important in distinguishing tinea cruris from other eruptions in the groin.
DIAGNOSIS AND DIFFERENTIAL
Identification of fungal elements on a KOH preparation or with fungal culture may be required if the diagnosis is uncertain. Typically, the diagnosis is made clinically.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Nonbullous tinea pedis and tinea manuum can be treated with topical antifungal agents, such as clotrimazole, miconazole, ketoconazole, or econazole, twice daily until 1 week after clearing has occurred.
Nail infections also should be treated with oral antifungal agents (itraconazole, fluconazole, or terbinafine) as well.
Bullous tinea pedis often does not respond to topical treatment; oral antifungal treatment is necessary.
Treatment of tinea cruris is with antifungal creams such as clotrimazole, ketoconazole, or econazole. Antifungal powders should be used on a daily basis to prevent recurrences.
Follow-up with a dermatologist if eruption does not resolve in 4 to 6 weeks.
CANDIDA INTERTRIGO
Candidal infections of the skin favor moist, occluded areas of the body.
Superficial candidal infections are commonly seen in the diaper area, the vulva and groin of women, the glans penis (balanitis) in uncircumcised males, and the inframammary and pannus folds of obese patients.
Antibiotic therapy, systemic corticosteroid therapy, urinary or fecal incontinence, immunocompromised states, and obesity are predisposing factors.
The typical presentation of candida intertrigo is erythema and maceration with surrounding small erythematous papules or pustules. The satellite pustules are a characteristic finding in differentiating between candida intertrigo and other inflammatory disorders affecting the skin folds.
KOH preparation of the pustules may demonstrate short hyphae and spores.
Apply stringent solutions like aluminum acetate to help dry weepy eruptions.
After drying, apply topical antifungals such as clotrimazole, ketoconazole, or econazole.
HUMAN SCABIES
CLINICAL FEATURES
Human scabies is an infestation of the skin by Sarcoptes scabiei. Scabies is transmitted by close physical contact or linens and clothing.
Scabetic mites burrow into the stratum corneum. The time from infestation to clinical symptoms is 4 to 6 weeks.
The eruptions are very pruritic. Hands, feet, elbows, knees, umbilicus, groin, and genitals may be involved.
Excoriations and pruritic papules may be the only visible clues.
In crusted scabies, hyperkeratosis develops on the hands and feet, with nails frequently affected.
DIAGNOSIS AND DIFFERENTIAL
Diagnosis is based on high clinical suspicion and positive scabies preparation.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Topical scabicides are applied from the neck down to the feet. Permethrin 5% cream and lindane 1% lotion are equally effective.
Lindane is neurotoxic in infants, children, and pregnant women.
Ivermectin, 200 micrograms/kg PO once, is an alternative to permethrin cream but should be avoided in pregnant and lactating women.
Oral antihistamines and topical corticosteroids help relieve symptoms.
PEDICULOSIS
CLINICAL FEATURES
Pediculosis capitis is an infestation of the hair and scalp with the mite Pediculus capitis, and occurs most commonly in school-aged children.
The louse is spread via close personal contact, clothing, and bed linens. Itching can be mild or intense.
Excoriation may be seen in the posterior neck and occiput.
Pediculus corporis (body lice) is less commonly seen. It typically occurs in overcrowded conditions with poor hygiene.
Bites are typically not felt by individuals, but red urticarial papules are left. Areas not covered by clothing are typically spared.
Pthirus pubis is pubic lice and is sexually transmitted.
DIAGNOSIS AND DIFFERENTIAL
Diagnosis of pediculosis capitis is made by visualization of lice and nits (eggs firmly attached to hair shafts) on physical examination.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Permethrin cream, 1% or 5%, is first-line therapy for head lice. It should be applied to the scalp overnight. Alternatively, pyrethrin cream can be applied for 10 minutes then rinsed out.
A repeat treatment is recommended in 1 to 2 weeks.
Treatment for pediculosis pubis and corporis is the same as for scabies above.
CONTACT DERMATITIS
CLINICAL FEATURES
Contact dermatitis may be a primary irritant reaction or an allergic-mediated event.
Agents capable of causing an aerosolized reaction include rhus (poison ivy and oak) when the plant has been burned.
Allergic contact dermatitis resulting from an aerosolized allergen presents with erythema or scaling, at times accompanied by blistering. The involvement is diffuse with upper and lower eyelids affected.
DIAGNOSIS AND DIFFERENTIAL
Direct application of the allergen produces similar findings on the most sensitive skin areas, such as the eyelids.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Corticosteroids (topical or oral, depending on the severity) are often required. Only low-potency topical corticosteroids (hydrocortisone 2.5%) should be used on the face; cream or ointment should be used initially. Alternatively, medium- to high-potency topical corticosteroids can be used on the face for no more than 3 to 5 days.
Extensive and severe periocular involvement requires oral prednisone.
Oral antihistamines are also useful in reducing pruritus.
PHOTOSENSITIVITY
CLINICAL FEATURES
Patients with sunburn have an inflammatory response to ultraviolet radiation and may present with minimal discomfort or extreme pain with extensive blistering.
A tender, warm erythema is seen in sun-exposed areas. Vesiculation may occur, representing a second-degree burn injury.
Exogenous photosensitivity results from either the topical application or the ingestion of an agent that increases the skin’s sensitivity to ultraviolet light.
Topically applied furocoumarins—lime juice, various fragrances, figs, celery, and parsnips—are the most common group of agents causing photoeruptions. Other topical photosensitizers include Para-Aminobenzoic Acid (PABA) esters and topical psoralens.
The exogenous photoeruption is similar to a severe sunburn reaction, often with blistering.
DIAGNOSIS AND DIFFERENTIAL
Sunburn should be suspected in a patient who has frequented the outdoors with significant ultraviolet light exposure.
The diagnosis of exogenous photosensitivity is based on identifying the offending agent.
A linear appearance to the rash suggests an externally applied substance.
EMERGENCY DEPARTMENT CARE AND DISPOSITION
Sunburns are treated symptomatically with tepid baths, oral analgesics, and burn wound care.
Initial management of exogenous photosensitivity is similar to the sunburn reaction, including the avoidance of the sun until the eruption has cleared. Any causative agent should be discontinued if possible.
PSORIASIS
Psoriasis vulgaris presents with erythema, scales, and fissures as discrete plaques located on palms and soles.
In pustular psoriasis erythema, some scaling and numerous pustules are seen on the palms and soles.
The diagnosis is usually made clinically. Biopsy may be helpful.
Treatment options include petroleum jelly, topical steroids, tar preparations, and vitamin D formulations.
For further reading in Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7th ed., see Chapter 246, “Disorders of the Face and Scalp,” by Dean S. Morrell and Emily J. Schwartz; Chapter 247, “Disorders of the Hands, Feet, and Extremities,” by Craig N. Burkhart and Dean S. Morrell; Chapter 248, “Disorders of the Groin and Skinfolds,” by Dean S. Morrell and Kelly Nelson; and Chapter 249, “Skin Disorders Common on the Trunk,” by Mark R. Hess and Suzanne P. Hess.