Approach to the Problem
The most common scaly rash in pediatrics is atopic dermatitis (eczema), which affects 15% to 20% of the pediatric population. While eczema tends to be chronic in nature, some patients have symptoms primarily during cold and dry weather. Other common causes of scaly rash include pityriasis rosea, tinea corporis, and seborrhea. Psoriasis and ichthyosis are less common. Initial lesions of pityriasis may at times be mistaken for tinea corporis, and ichthyosis may at times be mislabeled as severely dry skin. In general, most dry and scaly rashes tend to be pruritic in nature.
Key Points in the History
• The duration of symptoms will help to distinguish acute and subacute rashes, such as tinea corporis, from more chronic conditions, such as eczema.
• A family history of atopy should raise suspicion for eczema.
• Eczema generally spares the groin and diaper areas, whereas seborrhea does not.
• A solitary lesion may suggest tinea corporis or may be the herald patch seen in pityriasis rosea.
• Tinea corporis worsens with topical steroids, whereas eczema generally improves.
• Eczema on the face of young infants may have a circular area of erythema and may be misdiagnosed as tinea corporis.
• Cold weather generally exacerbates eczema, but some patients report worsening in the summer and winter months.
• In pityriasis rosea, the rash often starts as a single isolated lesion, a herald patch, followed by a more generalized rash occurring 5 to 10 days later.
• In the event a child shares a bed with another individual who denies pruritus or rash, a diagnosis of scabies is unlikely.
• Psoriasis affects 1% to 3% of the population, but it is uncommon in African Americans.
Key Points in the Physical Examination
• Patients with eczema often have dry skin, keratosis pilaris, or both.
• Lichenification is pathognomic of chronic atopic dermatitis when it appears in the expected distribution.
• Often, allergic shiners and Dennie–Morgan lines are seen in individuals with atopic dermatitis.
• Seborrhea generally stays within the hairline, whereas psoriasis extends beyond the hairline.
• In ectopic allergic contact dermatitis, the rash may not be in the expected location as can be seen with nail polish (tosylamide/formaldehyde) allergy.
• Lesions associated with tinea corporis tend to be round, whereas the herald patch in pityriasis rosea is oval.
• The generalized rash of pityriasis rosea classically runs parallel to the lines of skin cleavage, in a “Christmas-tree” distribution.
• In some individuals, the scaly lesions of pityriasis may be found in the pubic, inguinal, and axillary areas, and this is referred to as “inverse pityriasis rosea.”
•
Stay updated, free articles. Join our Telegram channel
Full access? Get Clinical Tree
