Characterization of Chronic Hand Eczema

This study is collecting detailed information about chronic hand eczema (CHE) — a persistent, often painful skin condition affecting the hands — as well as atopic dermatitis (AD, also known as eczema). Researchers will take skin samples, blood samples, and photographs to better understand the biology behind these conditions. You may be eligible if: - You are 18 to 65 years old - You have had moderate to severe chronic hand eczema for at least 6 months, OR you have moderate to severe atopic dermatitis, OR you are a healthy volunteer - You are willing to comply with all study visits and procedures You may NOT be eligible if: - You are pregnant or planning to become pregnant during the study - You used systemic antibiotics within 2 weeks before the study start - You received a biologic medication (like dupilumab) within 12 weeks before the study start - You have an active skin infection on your hands - You used topical eczema treatments within 1 week before the study start - You had recent UV phototherapy or PUVA treatment Talk to your doctor to see if this trial is right for you.