Generalized and/or disseminated eczema is challenging in terms of diagnosis and treatment. This condition can be a manifestation of atopic dermatitis or allergic contact dermatitis. In the latter, quality of life can be increased significantly by identifying and avoiding the relevant allergens.

With the aim of determining the usefulness of patch testing in affected individuals, we performed a retrospective study of 44 patients with generalized and/or disseminated eczema seen at our contact dermatitis department between 2013 and 2017. Eczema was considered generalized when it affected most of the body surface and disseminated when it affected 3 or more sites. We recorded variables associated with patients’ characteristics (age, sex, occupation, and diagnosis of atopic dermatitis), as well as the allergens assessed and the results of patch tests (positive allergens and their relevance). All patients were assessed using the standard series of the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC)1. Depending on the clinical setting, specific series were added (Chemotechnique) in some cases (26 patients), as were the patient’s own products (22 patients). Systemic corticosteroids and other immunosuppressive therapies were discontinued before patch testing. Testing was performed during remission periods. The drugs were restarted on the day of the last reading. Patients who could not suspend therapy were excluded. Data were collected using Microsoft Excel 2010, and the statistical analysis was performed using IBM SPSS Statistics for Windows, Version 20.1 (IBM Corp.).

Women accounted for 56.8% of the 44 patients (mean age, 57 years). Most were not working. The results of patch testing were positive in 28 cases (63%). Several patients had more than 1 positive result: a total of 54 positive results were recorded. Of the 28 patients, 16 (57.1%) had at least 1 relevant positive result. Table 1 shows the rates for positive results and relevance of the different allergens. Nickel was the most common allergen (18.5%), followed by isothiazolinones (14.8%) and paraphenylenediamine (5.6%). Isothiazolinones were the most relevant allergens (20.6%), whereas nickel and paraphenylenediamine had a relevance of 8.8% and 5.9%.

Atopic dermatitis was recorded in 25 patients (57%), with most diagnosed before testing. Atopic dermatitis was diagnosed more frequently after testing in patients with negative results (Table 2). We found no significant differences when we analyzed patients by age, sex, and occupation.

Our results support the use of patch testing in patients with generalized and/or disseminated eczema. Nickel was the most common allergen, whereas isothiazolinones were the most relevant. This finding is consistent with the high rate of sensitization to isothiazolinones during the study period. Nevertheless, a notable reduction has recently been detected, possibly owing to more restrictive legal measures2,3. We also detected positive results to many other allergens that are standard ingredients in cosmetics and hygiene products, especially preservatives. Our results agree with those reported elsewhere4–7. Therefore, the most widely reported allergens in affected patients are nickel4, balsam of Peru4, imidazolidinyl urea5, propyleneglycol5, diazolidinyl urea5, DMDM hydantoin5, paraphenylendiamine6, quaternium-157, and formaldehyde7.

It is interesting to note that most allergens yielding positive results were included in the standard GEIDAC series, except for limonene hydroperoxide (1.9%), linalool hydroperoxide (3.7%), and disperse orange 3 (1.9%). The inclusion of limonene hydroperoxide and linalool hydroperoxide in the Spanish standard series is somewhat controversial1,2. Given the high rate of positive results we recorded, we believe that their inclusion is justified. Moreover, all patients undergo testing for these allergens in our unit.

Therefore, in the initial study of patients with generalized and/or disseminated eczema in Spain, we recommended using the GEIDAC standard series, including limonene hydroperoxide and linalool hydroperoxide. Furthermore, depending on the clinical history, other series and the patient’s own products can also be tested.

Patch testing proved useful in the management of patients with generalized and/or disseminated eczema, even when the results were negative, since they made it possible to diagnose adult atopic dermatitis, as reported in the literature8,9.

Our study is limited by its reduced sample size and the fact that the determination of the relevance of the allergen was subjective. However, the paucity of data on patch testing in patients with generalized and/or disseminated eczema and the results we obtained constitute the rationale for the present study.

In conclusion, we recommend patch testing in patients with generalized and/or disseminated eczema, since they are a major aid for identifying and avoiding potentially involved allergens. Furthermore, negative results can help in the diagnosis of adult atopic dermatitis. Lastly, we recommend an initial study including the GEIDAC standard series, together with limonene hydroperoxide and linalool hydroperoxide.