The Itch That Rashes

Myths, Misconceptions, and Education in Eczema Management

Jeanne Findlay, CPNP, CCRP, DNP; Bernard A. Cohen, MD

Disclosures

February 02, 2011

Diagnosis and Pathophysiology

The child in this clinical case represents a classic presentation for AD. AD, or eczema, is a global skin disease that is among the top 3 skin complaints seen in pediatric dermatology specialty clinics. The prevalence of AD in the US pediatric population ranges from 8% to 18%.[1] The hallmark symptom for this very common, clinically diagnosed, chronic skin disease is itching, or pruritus. It is important to note that children with AD may frequently present with comorbid skin conditions, especially bacterial and viral skin infections

The underlying problem in AD is a malfunctioning skin barrier. Part of the reason the skin barrier is ineffective is due to a decreased amount of lipids, called ceramides, in the uppermost layers of the skin.[2] The lack of ceramides in turn increases the permeability of the skin resulting in increased water loss.

In approximately half of severely atopic individuals, the skin barrier is also less effective as a barrier due to a defect in the development of the protein, filaggrin.[3] Filaggrin contributes to the intactness of the skin barrier. When the skin barrier is ineffective, it also allows for the increased entry of bacteria. Colonization of the skin with bacteria contributes to increased inflammation and skin infections.[4] In turn, antigens produced by certain strains of Staphylococcus aureus have been shown to reduce the efficacy of some topical steroids that are commonly used to treat inflammatory skin flares.

Innate immunity may play a part in Maria's case because she was born with an immune system "preprogrammed" for her parents' native and more rural Honduras, rather than the industrialized United States. This can add to her skin's hypersensitivity to "typical" and common airborne irritants in the United States. Additionally, her age is another risk factor; her developing immune system is still a work in progress. Waning of passive immunity acquired during pregnancy is likely contributing to the development of eczematous skin lesions in the 5-month-old sibling.

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