AbstractAtopic dermatitis, commonly known as eczema, is a common chronic, relapsing skin disease characterized by pruritus, disrupted epidermal barrier function, and immunoglobulin E–mediated sensitization to food and environmental allergens. Atopic dermatitis is a complex disease that arises from interactions between genes and the environment. Loci on several chromosomes have been identified, including a family of epithelium‐related genes called the epidermal differentiation complex on chromosome 1q21. Mutations in filaggrin, a key protein in epidermal differentiation, have also been identified in early‐onset and severe atopic dermatitis. There are 3 classical stages of eczema: infantile, childhood, and adulthood. The spectrum of eczema presentation varies widely from a variant that only affect the hand to major forms where a patient presents with erythroderma. The acute and subacute lesions of atopic dermatitis are often characterized by intensely pruritic, erythematous papules and vesicles with excoriations and a serous exudate. Chronic atopic dermatitis is exemplified by lichenified plaques and papules with excoriations. Atopic dermatitis patients are also at higher risk for skin infections, including bacterial and viral superinfections. Conventional therapy includes avoidance of irritants and potential allergens, as well as continued hydration of the skin with thick emollients. Topical corticosteroids and topical immunomodulators are often used primarily. Other therapies including phototherapy, antimicrobials, antihistamines, and systemic immunosuppressives are also options in certain situations. Mt Sinai J Med 78:730–739, 2011. © 2011 Mount Sinai School of Medicine