Allergic Contact Dermatitis of the Hands: A Retrospective Cohort Study From Turkey Between 1996 and 2021

BACKGROUND: Allergic contact dermatitis (ACD) is a rare but significant cause of hand eczema (HE). OBJECTIVES: To evaluate positive patch test reactions in HE patients, focusing on frequency, clinical/occupational relevance and sources of exposure at a tertiary referral centre in Turkey. METHODS: Retrospective analysis of 1499 HE patients from 2533 consecutively patch-tested individuals (1996-2021). RESULTS: Positive patch test reactions occurred in 55.6% of HE patients, most commonly to nickel sulphate, potassium dichromate and thiuram mix. ACD was diagnosed in 34.2% of cases, with 54.1% being occupational, mainly in males. Occupational ACD was predominantly associated with potassium dichromate/cement among construction workers, and thiurams/rubber gloves among construction and healthcare workers. Non-occupational ACD (45.9%) was more frequent in females, typically associated with methylchloroisothiazolinone/methylisothiazolinone (MCI/MI), MI and fragrances in cosmetics and personal care products. Nickel was not a leading cause of HE; however, it was the inducer of systemic allergic dermatitis in 2.7% (14/512) of patients with hand ACD. Recurrent vesicular HE and bilateral dorsal, periungual, or wrist involvement were significantly associated with ACD. CONCLUSIONS: Nickel was a frequent sensitiser but an uncommon cause of hand ACD, often triggering systemic allergic dermatitis. Occupational ACD and male gender predominated. Recurrent vesicular HE and bilateral dorsal, periungual, or wrist involvement were key patterns helping identify patients for patch testing.