David L. Kaplan, MD

The parents of an 8-year-old boy seek evaluation of a red patch on their son's shoulder. The asymptomatic spot erupted 2 weeks earlier. The patient has seasonal allergies and frequently plays with his dog. 

 
 A. Psoriasis. 
 B. Tinea corporis. 
 C. Impetigo. 
 D. Contact dermatitis. 
 E. Erythema migrans. 

The parents of a 9-year-old girl are concerned about their daughter's rash that developed 1 week earlier. The asymptomatic eruption is primarily on the trunk. The patient has no history of contactant exposure, takes no medications, and has not had any recent illnesses. The family pets include a dog and a cat. 

 What is the most likely cause of this patient's rash?

 
 A. Pityriasis rosea. 
 B. Psoriasis. 
 C. Tinea corporis. 
 D. Nummular eczema. 
 E. Contact dermatitis. 

A potassium hydroxide evaluation confirmed tinea 

, which responded to a topical antifungal. The family was advised to have their dog examined by a veterinarian because the pet was the suspected source of the dermatophyte.

 Erythema migrans associated with Lyme disease was unlikely, since the patient had no prodromal symptoms and the lesion developed in winter, long after the tick bite transmission season. Because the single lesion was not pruritic and erupted on a site that was covered by clothing, patch tests for contact dermatitis were not warranted. The lesion demonstrated far less scale than is seen in psoriasis; the absence of tender, crusted vesicles ruled out impetigo.

Circular patches of scaling and erythema are clues to pityriasis rosea, A, a self-limited disease that may last for weeks to months. This patient exhibits signs of both the common form of the disorder and a papular variant. A corticosteroid cream and the anti-inflammatory effect of moderate exposure to sunlight cleared the outbreak. 

Psoriasis in this age group usually follows a streptococcal infection; this patient had no such history. Her rash was far too extensive to be tinea corporis. She had no history of atopy, which made nummular eczema unlikely. Contact dermatitis is pruritic and not as discrete as this patient's lesions. 

Articles

Tinea Corporis and Pityriasis Rosea

/2-year-old boy has had erythematous annular lesions on the lower trunk and proximal lower extremities. He was treated for pityriasis rosea only to have the lesions recur when the topical corticosteroid was discontinued.

A 16-year-old boy with atopy has been bothered for a few months by an intermittent rash on the distal dorsal aspects of both feet. He also complains of having sweaty feet.

This patient had nummular eczema attributable to his underlying atopic dermatitis. A new soap, moisturizer, and bathing regimen--washing only odor-bearing areas in lukewarm water with added bath oil--brought about marked improvement in the rash.

A contact dermatitis is not as well defined and tinea corporis usually is not as extensive as this rash. Viral exanthems do not last for several weeks. The distribution is slightly atypical for pityriasis rosea, but the disorder is included in the differential diagnosis.

Juvenile plantar dermatosis is seen in atopic patients with hyperhidrosis. It usually manifests as an erythematous rash on the distal third of the foot and spares the toe webs. Treatment includes keeping the foot dry (with foot powder and by frequently changing socks) and applying topical corticosteroid cream as needed. Patients outgrow this condition over a few years; it usually resolves by puberty.

Tinea pedis affects the toe webs but rarely involves the dorsum of the foot. This is an unlikely presentation for candidiasis, which generally affects immunocompromised persons--such as those with diabetes. Contact shoe dermatitis is common on the dorsum of the foot but rarely affects the toes. Hyperhidrosis does not cause a rash on the dorsum of the foot.	*

For several weeks, this 21/2-year-old boy has had erythematous annular lesions on the lower trunk and proximal lower extremities. He was treated for pityriasis rosea only to have the lesions recur when the topical corticosteroid was discontinued.

Nummular Eczema and Juvenile Plantar Dermatosis 

For several weeks, an 18-year-old man has been bothered by itchy ears. He has seasonal allergies that are well controlled with oral antihistamines. He has not been exposed to contactants and has not used any nutritional supplements or new shampoos or conditioners. He works out at a gym 5 days a week.

 A mid-potency topical corticosteroid helped relieve the symptoms. No obvious cause was identified.

Relapsing polychondritis is typically painful, not pruritic. Seborrheic dermatitis and psoriasis usually involve the external auditory canal and the area behind the ears. Contact dermatitis may be ruled out because there was no exposure history.

For several weeks, a 10-year-old boy's feet have been scaly and pruritic. He plays basketball and soccer and recently bought new shoes. A trial of over-the-counter miconazole was ineffective. The patient has a history of childhood eczema but outgrew it about 5 years ago.

The triad of sweaty feet, occlusive footwear, and a history of eczema suggests 

 Symptoms can be controlled if patients keep their feet dry by using foot powder and changing socks frequently. Topical corticosteroids or topical immunomodulators, such as tacrolimus and pimecrolimus, are also effective. Juvenile plantar dermatitis typically improves at puberty.

Contact dermatitis to shoes usually manifests on the dorsa of the feet. Tinea pedis is usually scalier and, unlike juvenile plantar dermatitis, involves the toe webs. Psoriasis is unlikely to involve just the soles and features more erythema and scale. Keratoderma is characterized by a thickened layer that produces a waxy appearance.

A 10-year-old boy has noticed asymptomatic discoloration on his back this summer. He has mild seasonal allergies that are controlled with over-the-counter medications. He plays soccer and has been swimming in a pool. He has had a dog and a cat for the past 2 years.

Which of the conditions in the differential is the likely diagnosis?

 a postinflammatory hypopigmentation associated with chronic eczema; it interferes with normal tanning. The patient was advised to change his bathing routine (no washcloth, lukewarm water, no antibacterial soaps, avoid washing rash) and to apply a moisturizer, sunscreen, and a low-potency topical corticosteroid.His skin color evened out during the next 4 to 6 weeks.

Vitiligo consists of permanent depigmentation, not reversible hypopigmentation. Tinea versicolor, tinea corporis, and pityriasis rosea all feature scaling, and the latter 2 are usually pruritic.

An 18-Year-Old Man With Itchy Ears

For several months, a 12-year-old boy has been bothered by intermittent pruritus of the feet. He is very active in sports all year, and his feet tend to perspire heavily. He has a family history of seasonal allergies. He says that the rash worsened after he used an over-the-counter hydrocortisone cream.

 Exacerbation of tinea pedis from hydrocortisone.

as a result of excessive foot perspiration from his athletic activities. This dermatosis can erupt on the plantar or dorsal surface and is more common in children than adults because the skin surface has not thickened yet. The diagnosis is based on a history of atopy and hyperhidrosis and negative results on a potassium hydroxide evaluation. The patient's condition was exacerbated by 

contact dermatitis to the hydrocortisone cream, A.

 Up to 5% of persons who undergo patch testing show contact hypersensitivity to corticosteroids, including hydrocortisone.

This patient responded to hygienic measures, such as keeping his feet dry, and a topical corticosteroid to which he was not sensitive.

Tinea pedis can be exacerbated by topical corticosteroids, but tinea is scalier than the condition seen here. Shoe dermatitis is usually confined to the dorsum of the feet and does not extend to the ankles. Impetigo presents with crusting erosions.

For several months, a 12-year-old girl has had asymptomatic erythematous papules on the sides of her nose.She is otherwise healthy.

Which condition is responsible for the eruption?

 that is common in preteenagers. This is generally a clinical diagnosis based on the appearance and location of the lesions. The dermatitis responded to a sulfacetamide/sulfur topical antibiotic. An antifungal cream is another treatment option.

Acne is not typically confined to the paranasal region. Keratosis pilaris typically is found in the mid-cheek area. Staphylococcal and candidal infections are more inflammatory and symptomatic.

For several weeks, an 11-year-old girl has had itchy shins. She plays soccer and wears shin guards. Although she bathes frequently, she has not used any new soaps. The family has a dog, and there is a family history of asthma.

attributable to a combination of abrasion from the shin guards and bathing twice a day.

Scabies would be more widespread after a few weeks. The lesions of contact dermatitis are usually more confluent than the discrete lesions seen here. Psoriasis would be more erythematous and scaly. Lichen simplex chronicus would be considered if the patient did not respond to moisturizers and mild topical corticosteroids.

 Bircher AJ, Thurlimann W, Hunziker T, et al. Contact hypersensitivity to corticosteroids in routine patch test patients. A multi-centre study of the Swiss Contact Dermatitis Research Group. 

Juvenile Plantar Dermatosis and Seborrheic Dermatitis

A 5-year-old girl is brought for evaluation of an asymptomatic inflamed streak on one leg that has been present for several weeks. She is otherwise healthy and takes no medications.

a self-limited papular eruptionthat occurs primarily in children and affects twice as many girls as boys. The eruption persists for months before resolving spontaneously. No treatment is necessary, although some lesions respond to topical corticosteroids.

Psoriasis consists of discrete scaly lesions. Contact dermatitis is pruritic. Lichen planus features discrete flat-topped polygonal purple papules. Lichen sclerosus is characterized by hypopigmented coalescing macules.

A 7-year-old boy has had an asymptomatic papular eruption on the trunk and extremitiesfor several weeks. He is otherwise healthy.

 a condition of unknown cause sometimes seen in children, generally lasts for several months before resolving. There is no known treatment.

Follicular eczema is usually seen only in atopic persons. 

folliculitis is typically confined to the trunk. Lichen planus is pruritic and consists of flat purple polygonal papules. Keratosis pilaris preferentially affects atopic persons and is confined to the upper outer arms, upper outer thighs, and cheeks.

Irritation at the angle of the lips on the right side bothers a 14-year-old boy. The rash failed to respond to an antifungal cream prescribed by another practitioner. The patient has been using isotretinoin for acne for 3 months.

Irritation caused by a vitamin deficiency.

Recommend achange in the brand of oral hygiene products used.

 A culture of material from this patient's lip,

 infection can mimic this bacterial condition; if the patient's disease fails to respond to antifungal therapy, mupirocin cream may be tried or a bacterial culture can be performed.

Contact dermatitis to oral hygiene products usually produces a circumferential swelling around the vermilion border of the lips. The eruption caused by a vitamin B

Most likely, isotretinoin-induced dryness of the lips predisposed this patient to cheilitis, as well as to the staphylococcal infection. The patient was advised to use lip moisturizer, 

regularly. Mupirocin cream quickly cleared the infection. The patient has had no further episodes.

Lichen Striatus and Lichen Nitidus

For several weeks, a 6-year-old girl has had a worsening mildly pruritic rash on the trunk. She has a history of seasonal allergies. The family has had a cat and a dog in the house for a number of years.

 which is more common in children and in young adults than in older adults. This self-limited eruption typically presents with oval macules that are more or less pruritic. The condition usually runs its course over several weeks; topical corticosteroid creams relieve the symptoms. Tinea corporis, nummular eczema, asteatotic eczema, and contact dermatitis do not present with multiple discrete lesions as small as these. Lichen simplex chronicus is unusual in children and does not feature such numerous lesions.

It is unlikely that a dermatophyte infection would produce so many lesions so quickly--so the family pets cannot be blamed.

A 10-year-old girl who plays soccer at school has had pruritic papules on her elbows for several weeks. She has not been exposed to any new detergents or new clothing. Her family has a cat and a dog. No one else in the family has similar lesions, although her brother has seasonal allergies.

 This condition generally presents in children aged 2 to 12 years as pruritic papules in the flexural areas. The rash can be controlled with moisturizers and low-potency topical corticosteroids.

Scabies would generally be more widespread after a few weeks. Psoriasis is more scaly and patchy. Lichen spinulosus may erupt on the elbows in atopic patients, but it typically is asymptomatic. Granuloma annulare is also asymptomatic.

It is unlikely that a dermatophyte infection would produce multiple discrete pruritic papules like these on the elbows. Thus, the family pets are not a likely source.

A 12-year-old boy presents with a symmetric pruritic rash on his arms and legs that has coincided with the onset of his seasonal allergies. He has taken montelukast and cetirizine for years. He participates in sports year-round and sometimes takes more than 1 shower a day. The family owns a dog and a ferret.

The synchronous occurrence of atopic dermatitis and a respiratory condition is seen occasionally. The patient's dermatitis was exacerbated by excessive bathing, a habit common among adolescents. His condition improved with a regimen of fewer showers, moisturizers, and a moderately potent topical corticosteroid.

Neither montelukast nor cetirizine is likely to produce a cutaneous drug reaction such as the one seen here. The pattern and location of the patient's rash are not typical of contact dermatitis. Psoriasis is scalier than this patient's rash. It is unlikely that a dermatophyte eruption would arise so quickly and be so extensive.

Dermatophytic infection is not usually this extensive unless the patient is immunocompromised. Thus, the patient's dog and ferret are off the hook.

An 8-year-old girl presents with a pruritic rash of several weeks' duration in the antecubital fossae. There is a family history of seasonal allergies, and the family has a 2-year-old dog.

 The results of a potassium hydroxide evaluation were negative, which supported the diagnosis of 

 This condition, known colloquially as "the itch that rashes," preferentially affects large flexural surfaces, such as the antecubital and popliteal fossae. 

It is highly unlikely that candidiasis or a dermatophyte infection would be bilateral. The antecubital fossae are not a typical location for contact dermatitis. Impetigo features oozing and crusting.