Background: Oral lichen planus is an idiopathic autoimmune inflammatory condition and oral lichenoid reactions are lesions that resemble oral lichen planus clinically and histopathologically, but develop secondary to various underlying causes. Oral lichenoid reactions have been reported to be caused by contact allergy to dental materials. This study aims to describe the characteristics of patients with a clinical and/or histopathological diagnosis of oral lichen planus who underwent patch testing in Hospital Kuala Lumpur, Malaysia. Methods: This is a 5-year retrospective study of patients who had oral lichen planus and had undergone patch testing at the Department of Dermatology, Hospital Kuala Lumpur, Malaysia between January 2015 and Cecember 2019. Patch tests were performed with European Baseline Series and relevant extended series, which include dental and metal series as well as patients’ own products. Patch test results were recorded according to the International Contact Dermatitis Research Group recommendation. Results: There were 41 patients with oral lichen planus who underwent patch test. The median age was 56 (range 21 to 73) with 70.7% of patients being female. There were 29 (70.7%) patients who developed at least one positive reaction. The most frequent sensitizing allergens were nickel sulfate (34.1%), gold(I)sodium thiosulphate dihydrate (22.0%), fragrance mix I (19.5%), cobalt chloride (14.6%), Peru balsam (12.2%) and sodium tetrachloropalladate (II) hydrate (12.2%). Current relevance was recorded in 16 patients (39.0%) and of these patients, 12 of them had positive patch test reactions to allergens found in dental materials such as dental fillings, dental implants, orthodontic braces, dentures and dental crowns. Conclusion Contact sensitization was detected in about 70% of our patients with oral lichen planus. The most common sensitizing allergen was nickel sulfate. Current relevance was found mainly towards dental materials.
Lichen Planus, Oral--diagnosis ; Dermatitis, Allergic Contact ; Department of Dermatology, Hospital Kuala Lumpur (Malaysia)