CD20 Allergic contact dermatitis due to a rosary necklace

Abstract Exposure to various exotic woods can cause allergic contact dermatitis. We report a rare cause of allergic contact dermatitis after exposure to Brazilian walnut hardwood, from the tree Ocotea porosa. A 61-year-old man presented with a 1-year history of an ongoing erythematous and itchy rash, initially appearing on the upper back and neck in May 2024. The rash had spread to involve the upper body, chest and face, with particular focus on the periorbital area. The rest of the body remained unaffected. The patient had a past medical history of hay fever, hypertension and recurrent cold sores, and took antihypertensives, antivirals and lansoprazole. There was a maternal history of eczema. He worked as a canal boat salesman but had no chemical exposure at work. Of note the patient had purchased a rosary bead necklace from Amazon in May 2024. Evaluation of the manufacturer sheet revealed that the wood used for its production was Brazilian walnut hardwood. Patch testing was performed with the British standard, cosmetic, fragrance and hairdressing series, used under occlusion with IQ Ultra chambers. Scrapings from the wood material were applied to the skin as is. Readings were done on day 2 and day 4. He was positive to balsam of Peru 1 + and the dust and scraping from the rosary beads 1 + on day 4. Ocotea porosa, commonly called imbuia or Brazilian walnut, is a species of plant in the family Lauraceae. It is a major commercial timber species in Brazil and its attractive grain has contributed to its long-standing popularity in high-end furniture and flooring. Allergic contact dermatitis to wood is usually associated with occupational wood dust exposure, which causes an airborne contact dermatitis that can affect exposed sites directly, and nonexposed skin through friction and sweating. Inhalation may also cause involvement of the mucous membranes and/or respiratory tract. Although allergic contact dermatitis from wood is rare, exotic wood from tropical and subtropical regions contains potent allergens (mainly quinones). Moreover, crossreactivity among exotic woods is common, as their allergens share similar structures. To the best of the authors’ knowledge, this is the first reported case of a contact allergy to O. porosa. A search conducted on PubMed and Google Scholar was unable to find any further case reports reporting this. Future work to elucidate the allergens within O. porosa should be completed, as well as its sensitizing capacity.