Atopic Dermatitis in Adults

Licia Zeppa; Veronica Bellini; Paolo Lisi

Disclosures

Dermatitis. 2011;22(1):40-46. 

In This Article

Discussion

Numerous original articles, reports, and reviews have been published about AD in infants and children. However, the epidemiologic and clinical aspects and the factors that play a role in triggering and sustaining the AD persisting in adulthood or the AD developing de novo in adults have been less investigated. There are only a few studies on AD in adults, and these are based on hospital patient records[19–23] or questionnaires.[24]

Our study has confirmed no significant preponderance of females among adult AD patients.[17,18,20] This is in contrast to other investigators' results,[21,24] but the discrepancy could be due to the different selection of patients (Italian Navy Hospital patients) in one instance[21] and the different investigative method (questionnaires) in another.[24] The higher prevalence in females than in males seems to be typical for adult AD because it was not found for AD in infants and children.[25]

Our results also show large differences in adult AD prevalence among age groups. The mean age of our patients was 30.4 years, without significant relationship to sex. The disease was progressively less frequent in successive decades and very rare in patients older than 57 years. The same age-related trend was reported by Ozkaya[22] among 63 patients with AD that began after the age of 18 years and by Saeki and colleagues[23] among Japanese government officials or their family members visiting the Health Service Center for an annual health checkup.

Adult AD has a broad range for age at onset, but this study suggests that AD is a childhood disease that extends into adult life in only half (52.4%) of cases. Therefore, the early age of onset (infancy and childhood) is a less important diagnostic criterion for adults than for those in other periods of life.

As with AD in children, AD in adults is based primarily on historical and clinical data, but IgE levels and the results of skin-prick tests with environmental allergens may be useful. However, the association with rhinoconjunctivitis and asthma (57.8%), elevated serum total IgE levels (61.7%), and one or more positive results of skin-prick tests with aeroallergens (59.6%) seems to be more prevalent than is a positive history for atopic diseases in first-degree relatives (36.7%) and sensitivity to food allergens (11.4%). The results were not statistically correlated with the sex of patients or the age at AD onset.

The diagnostic value of family history is less important in adult AD than in childhood-onset AD, for which prevalence varies between 58% and 68%.[24] This could be due to the lesser reliability of anamnestic data at this time.

The role of food allergens as an aggravating factor is less important in adults, although pollen-associated food allergens have been suggested as playing a role in up to 15% of severely affected patients with AD.[26] Moreover, sensitivity to classic food allergens such as milk and eggs has been shown only rarely (7.4%) and often is not clinically relevant.[27]

The diagnosis of adult AD is mostly clinical and is based on the typical morphology and distribution of lesions. The picture is similar to that in later childhood, with lichenification, especially of the antecubital flexures, eyelids, perioral region, and popliteal flexures. However, involvement of the forehead, cheeks, and anterolateral region of the neck is very common in adults,[24,28] whereas the frequency of hand involvement is variable (50.0% according to Sandström Falk and Faergemann[28] and 12.8% in our study). When the hands are affected, the differential diagnosis between AD and irritant contact dermatitis may be difficult. Diagnosis is enabled by (1) the lichenified and minimally phlogistic aspect of the lesions, (2) the lesions' sharp margins and symmetrical distribution, (3) the prevalent localization on the backs of the hands and fingers (especially the knuckles) and on the volar side of the wrists, (4) severe pruritus, (5) a chronic course with temporary remissions in summer, (6) an association with atopic mucous manifestations, (7) a positive family history of atopy, and (8) increased serum IgE levels.

Adult AD may sometimes have atypical morphologic aspects such as nummular, follicular, prurigo-like, and seborrheic dermatitis.[22,29] Neck pigmentation (also called ripple pigmentation, dirty neck, or poikiloderma-like skin changes) has also been reported.[30,31] However, xerosis of uninvolved skin and itching are constant and are most severe in the winter months.

The role of contact allergy in AD patients is often underestimated. Our study showed a high prevalence of positive patch-test reactions (23.8%), which were significantly more common in females than in males (p < .05), as we reported previously.[32,33] The most common sensitizers were metals (nickel sulfate, cobalt chloride, and potassium dichromate) and fragrance, but their clinical relevance was not always evident. However, the identification of contact allergens is very important because it may influence the clinical course of AD, the patient's occupational choices, and the development of hand dermatitis among those who work in certain occupations (such as hairdressers, cleaners, metalworkers, mechanics, and nurses). The data support the importance of patch testing and preventive strategies for AD patients when occupational choices are made, especially when these choices implicate exposure to sensitizing compounds.

The positive patch-test reactions were not related to the two subtypes of AD (IAD and EAD). In our series, the prevalence of adult IAD (30.4%) was slightly higher than the mean values (20%) reported by others in children or in groups of patients of various ages who are affected by AD.[34–36]

As with infants and children,[37] IAD in adults does not differ from EAD with regard to age at onset and to the features and distribution of lesions, whereas it is significantly more common in females (70.3% for IAD vs 50.2% for EAD) than in males and in the youngest adults (mean age, 27.1 yr for IAD patients vs 31.6 yr for EAD). It is possible that some IAD patients could develop respiratory allergies or allergic conjunctivitis in the future. The prevalence of atopic diseases in relatives was significantly higher among EAD subjects than among IAD subjects.

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