Patch Testing Reveals Key Allergens in Hand and Foot Eczema

Hand and foot eczema remains one of the most frequently encountered dermatologic conditions in outpatient practice and continues to present diagnostic and therapeutic challenges due to its multifactorial etiology. Both endogenous factors, such as atopy, and exogenous exposures—including occupational irritants and allergens—contribute to disease onset and persistence.¹ Identifying relevant triggers is therefore a central component of management. A prospective observational study conducted at a tertiary care hospital in Chromepet, Chennai, India, evaluated the diagnostic utility of patch testing in patients with hand and foot eczema and examined clinical patterns and potential etiologic factors.²

Study Design and Methodology

The study was conducted over an 18-month period from May 2023 to October 2024 in the dermatology outpatient department of a tertiary care center. Investigators enrolled 30 adult patients clinically diagnosed with hand and/or foot eczema. Patients who had taken immunosuppressive therapy within the previous 2 weeks or antihistamines within 72 hours were excluded, as were pregnant individuals and those with active eczema at other body sites.

After obtaining informed consent, demographic and clinical data were collected using a standardized pro forma. Clinical evaluation included documentation of symptom patterns, morphology, occupational and environmental exposures, history of atopy, and seasonal variation.

All participants underwent patch testing using the Indian standard series, which includes 20 commonly implicated allergens. Patch test chambers were applied to the upper back and removed after 48 hours. Readings were performed at both 48 and 72 hours according to the International Contact Dermatitis Research Group grading system.

Data were analyzed using SPSS version 22, with statistical significance defined as P < .05.

Clinical Characteristics

The study population consisted of 18 men (60%) and 12 women (40%). The majority of patients (53.3%) were between 41 and 60 years of age.

Hand involvement was the most common presentation, affecting 19 patients (63.3%), whereas foot eczema occurred in 6 patients (20%). Five individuals (16.7%) had involvement of both hands and feet. Bilateral disease was observed in 25 patients (83.3%), reflecting the typically diffuse or symmetrical nature of the condition.

Pruritus was the most frequently reported symptom, affecting 96.7% of patients. Other commonly reported features included dryness (80%) and scaling (63.3%). Vesiculation and oozing were each observed in approximately one-third of patients, whereas fissuring, pain, and erythema were less frequently reported.

Hyperkeratotic hand and foot eczema was the most common morphological subtype, present in 20% of patients. Keratolysis exfoliativa was the second most frequent pattern (16.6%), whereas other forms, such as fingertip eczema, irritant contact dermatitis, and dyshidrotic variants, were less commonly identified.

Exposure Patterns and Risk Factors

Occupational and environmental exposures were common among participants. The most frequently reported exposure was to gloves, documented in 50% of patients. Detergents were reported in 30% of cases, and exposure to cement was reported by 23.3%. Additional exposures included footwear, socks, plants, and hand sanitizers.

Atopy was present in 43.3% of patients, suggesting that underlying atopic predisposition may contribute to disease susceptibility or severity in a subset of individuals. Seasonal exacerbations were relatively uncommon, with a small number of patients reporting worsening during winter or monsoon months.

Patch Test Findings

Patch testing yielded positive reactions in 43.3% of patients. Nine patients (30%) had 1 positive antigen, 3 patients (10%) had reactions to 3 allergens, and 1 patient (3.3%) had 2 positive allergens. However, the majority of patients (56.7%) showed no positive reactions at the 72-hour reading.

Among those with positive results, the most frequently identified allergen was potassium dichromate, accounting for 25% of positive reactions. Paraphenylenediamine and thiuram mix were the next most common allergens, each identified in 15% of positive cases. Additional allergens included parthenium, black rubber mix, fragrance mix, and chlorocresol.

Notably, among the 7 patients with documented exposure to cement, 5 demonstrated patch test positivity to potassium dichromate, consistent with established associations between chromium exposure and occupational contact dermatitis in construction-related settings.

Clinical Implications

The findings reinforce the multifactorial nature of hand and foot eczema and highlight the importance of allergen identification in guiding management. Although more than half of the patients in this cohort had negative patch test results, the test still provided clinically relevant information in a substantial proportion of cases.

The predominance of hand involvement and the frequency of exposures to gloves, detergents, and cement underscore the strong occupational component of many cases. Identification of allergens such as potassium dichromate and rubber accelerators can inform targeted avoidance strategies, which remain a cornerstone of treatment.

Limitations

The authors acknowledge several limitations. The study’s relatively small sample size and single-center design may limit generalizability. In addition, the use of a standard allergen panel may not capture all potential region-specific or occupational allergens.

Conclusion

Hand and foot eczema continues to pose diagnostic and management challenges due to its chronic course and diverse etiologies. In this observational study, hand eczema was more prevalent than foot eczema and was frequently associated with occupational exposures. Patch testing identified relevant allergens in nearly half of the patients, with potassium dichromate emerging as the most common sensitizer. These findings support the continued role of patch testing as a noninvasive diagnostic tool that can guide allergen avoidance strategies and contribute to more individualized management of eczema.

References

1. Weisshaar E. Chronic hand eczema. Am J Clin Dermatol. 2024;25(6):909-926. doi:10.1007/s40257-024-00890-z
2. Balakumaran C, Sukanya G, Kumar NA, Megalai AS, Sankeerthana MP, Rajeev K. A study assessing patch test results in hand and foot eczema patients at a tertiary care hospital. Niger Postgrad Med J. 2026;33(2):285-288. doi:10.4103/npmj.npmj_167_25