Contact dermatitis due to nickel allergy in patients suffering from non-celiac wheat sensitivity

Background: Non‐celiac wheat sensitivity (NCWS) is a new clinical entity in the world of gluten‐related diseases. Nickel, the most frequent cause of contact allergy, can be found in wheat and results in systemic nickel allergy syndrome and mimics irritable bowel syndrome (IBS). Objective: To evaluate the frequency of contact dermatitis due to nickel allergy in NCWS patients diagnosed by a double‐blind placebo‐controlled(DBPC)challenge,and to identify the characteristics of NCWS patients with nickel allergy. Methods: We performed a prospective study of 60 patients (54 females, 6 males; mean age 34.1 ± 8.1 years) diagnosed with NCWS from December 2014 to November 2016; 80 age‐ and sex‐matched subjects with functional gastrointestina l symptoms served as controls. Patients reporting contact dermatitis related to nickel‐containing objects underwent nickel patch test (Clinicaltrials.gov registration number: NCT02750735).Results: Six out of sixty patients (10%) with NCWS suffered from contact dermatitis and nickel allergy and this frequency was statistically higher (p = 0.04)than observed in the control group(5%. The main clinical characteristic of NCWS patients with nickel allergy was a higher frequency of cutaneous symptoms after wheat ingestion compared to NCWS patients who did not suffer from nickel allergy (p < 0.0001. Conclusions: Contact dermatitis and nickel allergy are more frequent in NCWS patients than in subjects with functional gastrointestinal disorders;furthermore, these patients had a very high frequency of cutaneous manifestations after wheat ingestion. Nickel allergy should be evaluated in NCWS patients who have cutaneous manifestations after wheat ingestion.