Hand eczema in Italian patients referred for patch testing: A retrospective SIDAPA study (2016-2023)

Background: Hand eczema (HE) is a common skin disease with a negative impact on patients' quality of life in occupational and non-occupational settings. Up-to-date, data on HE in Italian patients referred for patch testing are lacking. Objectives: To characterise the profile in terms of demographics, aetiology and patch test results of Italian patients affected by HE referred for patch testing. Methods: A retrospective descriptive study on consecutive patients affected by HE who underwent patch testing from 2016 to 2023 in eight dermatology clinics was performed. HE patients were divided into two groups according to the exclusive (HE-only group) and not-exclusive (HE+ group) hand involvement, and compared to patients with eczema localised in body areas other than hands (NHE group). Results: One thousand five hundred and ninety-seven patients were affected by HE (35.3% males; mean age 42.7 years), 60.2% belonging to the HE-only group and 39.8% to the HE+ group. Occupational dermatitis was diagnosed in 33.2% of HE-only patients, 25.0% of HE+ patients and 5.2% of NHE patients (p < 0.001). HE-only patients presented: Allergic Contact Dermatitis (ACD), Irritant Contact Dermatitis (ICD), atopic HE in 48.1%, 47.5% and 7.1%, respectively; hyperkeratotic palmar, acute recurrent vesicular and nummular clinical subtypes in 52.2%, 43.9% and 11.9%, respectively; relevant positive patch test reactions in 48.1% (nickel sulphate 18.9%, methylchloroisothiazolinone/methylisothiazolinone 10.6%, methylisothiazolinone 8.6%, p-phenylenediamine 6.0% and potassium dichromate 4.7%). Conclusions: HE patients, and particularly those with exclusive hand involvement, show a particular profile in terms of demographic and clinical characteristics, etiologies and relevant positive patch test reactions.