Atopic dermatitis This condition is the most common of all pediatric dermatoses. For the majority of patients, the onset occurs during infancy. The classic facial appearance in this age group is illustrated in Figs. 9-1, 9-2, 9-3, 9-4.

There are symmetrical patches of erythema, exudation, and scale involving the cheeks and chin. It is not unusual also to see widespread involvement of the trunk and extensor extremities during infancy; the diaper area is most often spared.

Atopic dermatitis Pruritus is a cardinal feature of atopic dermatitis and may be evidenced in the infant by irritability, scratching, and rubbing against nearby objects.

Atopic dermatitis is an inherited disorder. Children with the disease most often have a family history of the atopic diathesis (atopic dermatitis, asthma, or allergic rhinitis) and may themselves manifest asthma or allergic respiratory disease.

Atopic dermatitis Figure 9-5 shows a severe case of atopic dermatitis with early evidence of impetiginization.

Figure 9-6 shows a similar distribution in an older child. In this case, also, impetiginization may be contributing to the crusted appearance of the lesions.

Atopic dermatitis When the diagnosis of atopic dermatitis is in doubt, the search for associated clinical findings is often helpful. The Dennie-Morgan line is a double fold under the eye, which is seen in many children with atopic dermatitis.

Pictured here is another child with periocular involvement. Children who suffer from seasonal allergies with associated conjunctivitis and itching may have worsening of the erythema, scale, and lichenification around the eyes during “allergy season”.

Atopic Dermatitis Figure 9-9 shows another telltale sign: a fissure at the junction of the pinna of the ear and the face. Other associated findings related to atopic dermatitis include lichen spinulosus (Fig. 9-23), pityriasis alba (Figs. 9-24 and 9-25), ichthyosis vulgaris (Figs. 15-1, 15-2, 15-3, 15-4), and keratosis pilaris (Figs. 15-63 and 15-64). Children with atopic dermatitis are also frequently noted to have hyperlinear palms and soles. Keratoconjunctivitis and cataracts may occur in the child with atopic dermatitis.

Atopic dermatitis During childhood, the most common locations of atopic dermatitis are the antecubital and popliteal fossae and the posterior neck. Figures 9-10 and 9-11 show children in whom the involvement is more widespread. The lesions show the characteristic erythema, oozing, and crusting of acute atopic dermatitis.

The exact pathogenesis of atopic dermatitis remains a mystery. Patients with the disease seem to have altered autonomic function and increased plasma histamine levels. Many have elevated levels of IgE, but some are completely normal in this respect. However, none of these observations has yet provided a basis for understanding the chronic and recurrent skin lesions of atopic dermatitis. An inherited abnormality in filaggrin expression affects barrier function and seems to be associated with this disease in some children.