In the last few years, a new clinical entity has emerged which includes patients who consider themselves to be suffering from problems caused by wheat and/or gluten ingestion, even though they do not have celiac disease (CD) or wheat allergy. This clinical condition has been named non-celiac gluten sensitivity (NCGS), although in a recent article, the investigators suggested the term "non-celiac wheat sensitivity" (NCWS), because it is not known to date what component of wheat actually causes the symptoms. Nickel is the fourth most used metal and the most frequent cause of contact allergy in the industrialized world. As a natural element of the earth's crust small amounts are found in water, soil, and natural foods, especially plant ones. Nickel allergy not only affects the skin but also results in systemic manifestations. Systemic nickel allergy syndrome can have cutaneous (urticaria/angioedema, flares, itching), and/or gastrointestinal (meteorism, colic, diarrhoea) signs and symptoms. In this study, the investigators evaluated 1) the frequency of Nickel allergy and Systemic Nickel allergy syndrome in NCWS patients, and 2) the clinical, serological, and histological characteristics of NCWS patients with contact dermatitis Nickel positive in comparison to NCWS patients without contact dermatitis.