The clinical manifestations of atopic dermatitis vary with age. In infants, atopic dermatitis involves the face, scalp, cheeks, and extensor surfaces of the extremities (Fig. 80-1). The diaper area is spared. In older children, the rash localizes to the antecubital and popliteal flexural surfaces, head, and neck. In adolescents and adults, lichenified plaques are seen in the flexural areas (Fig. 80-2) and the head and neck regions. Itching or pruritus has a significant impact on the child and family’s quality of life; it is often worse at night, interrupting sleep. Physical examination may show hyperlinearity of the palms and soles, white dermatographism, pityriasis alba, creases under the lower eyelids (Dennie−Morgan folds or Dennie lines), and keratosis pilaris (asymptomatic horny follicular papules on the extensor surfaces of the arms).
Figure 80-1 Atopic dermatitis typical cheek involvement. (From Eichenfield LF, Frieden IJ, Esterly NB: Textbook of Neonatal Derma-tology, Philadelphia, 2001, Saunders, p 242.)
Figure 80-2 Rubbing and scratching the inflamed flexural areas cause thickened (lichenified) skin. (From Habif T: Clinical Dermatology, ed 4, Philadelphia, 2004, Elsevier.)
The diagnosis of atopic dermatitis is based on clinical features rather than laboratory tests (Table 80-1). Skin biopsy is of little value, but it may be used to exclude other skin diseases that mimic atopic dermatitis. Skin testing or, alternatively, CAP fluorescent immunoassay (also known as FEIA) may be helpful in assessing the contribution of food or environmental allergies to disease expression.
Many conditions share signs and symptoms of atopic dermatitis (Table 80-2). Infants presenting in the first year of life with failure to thrive, recurrent skin or systemic infections, and scaling, erythematous rash should be evaluated for immunodeficiency disorders. Wiskott-Aldrich syndrome is an X-linked recessive syndrome characterized by atopic
The diagnosis requires evidence of itchy skin (or parental report of scratching or rubbing) plus three or more of the following: 1.
History of involvement of skin creases 2.
History of asthma or allergic rhinitis (or history of atopic disease in a first-degree relative if child is <4 years of age) 3.
History of generally dry skin in the past year 4.
Onset in a child <2 years of age (criterion not used if child is <4 years of age) 5.
Visible flexural dermatitis (including dermatitis affecting cheeks, forehead, and outer aspects of limbs in children <4 years of age)
Modified from Williams HC, Burney PG, Hay RJ, et al: Diagnostic criteria for atopic dermatitis. III. Independent hospital validation. Br J Dermatol 131:406–416, 1994.
Zinc deficiency Pyridoxine (vitamin B6) and niacin deficiency Multiple carboxylase deficiency, phenylketonuria
From Leung DYM: Atopic dermatitis. In Leung DYM, Sampson HA, Geha RS, et al, editors: Pediatric allergy: principles and practice, St Louis, 2003, Mosby, p 562.
IPEX, Immunodeficiency polyendocrinopathy X-linked.