Atopic dermatitis, commonly known as eczema, is a chronic, relapsing skin condition resulting from a Type I hypersensitivity reaction. In this reaction pathway, Immunoglobulin E (IgE) antibodies occupy receptor sites on mast cells, triggering mast cell degranulation and the subsequent release of histamine. This chemical cascade leads to vasodilation, mucous gland stimulation, and localized tissue swelling.
Clinical Concept: Type I hypersensitivity reactions are generally divided into two subgroups: atopy and anaphylaxis. The atopy subgroup includes common conditions such as allergic rhinitis, atopic dermatitis, allergic gastroenteropathy, and allergy-based asthma, all of which share a strong familial component.
The cardinal symptom of atopic dermatitis is severe pruritus (itching), which follows an intermittent course characterized by acute flares and remissions. Primary physical exam findings include:
Diagnosis is made clinically based on patient history and physical presentation. Standard diagnostic criteria require the presence of itching and subsequent scratching, plus three or more of the following:
Differential Diagnosis: When evaluating suspected atopic dermatitis, clinicians should rule out lichen simplex chronicus, nummular dermatitis, plaque psoriasis, scabies, seborrheic dermatitis, and tinea corporis. Routine skin cultures yield normal skin flora and are not indicated; however, allergen testing can be useful in refractory cases.
Baseline non-pharmacologic management focuses on avoiding triggers, restoring the compromised skin barrier, minimizing soap/water exposure, and maintaining consistent lubrication. When flares occur, step-up pharmacotherapy is indicated:
| Therapy Class | Medications / Interventions | Clinical Considerations |
|---|---|---|
| Soothing Dressings | Cool, wet dressings or Burow’s solution (Domeboro®) | Apply for 30 minutes to provide acute symptom relief. |
| Topical Corticosteroids | Intermediate- to low-potency formulations | Use intermediate-potency to control acute flares, stepping down to the lowest effective potency once controlled. |
| Topical Immunomodulators | Pimecrolimus (Elidel®), Tacrolimus (Protopic®) | Non-corticosteroid options that block T-cell stimulation and mast cell activation; indicated after other options fail; contraindicated in children <2 years. |
| PDE-4 Inhibitors | Crisaborole (Eucrisa®) | Topical ointment approved for mild-to-moderate disease in adults and children ≥2 years old (applied twice daily). |
| Biologics | Dupilumab (Dupixent®) | Subcutaneous monoclonal antibody for moderate-to-severe refractory disease. |
Pruritus is often reported by patients as more bothersome than pain. Because itching tends to worsen at night—causing severe sleep disturbances—bedtime oral antihistamines play a crucial role in therapy.
1. Barankin B, Anatoli F. Derm Notes: Clinical Dermatology Pocket Guide. Philadelphia, PA: F.A. Davis; 2006.
