P56Occupational protein contact dermatitis from shiitake mushrooms

Case report:  A 54‐year‐old woman, with no family or personal history of atopy, developed skin symptoms and cough after she had been cultivating shiitake mushrooms for 12 months. The patient reported dermatitis on the backs of her hands, fingers and on her wrists, after 1 or 2 days of being in contact with shiitake mushrooms. The skin lesions and cough disappeared entirely during the holidays. Result: Prick tests to common inhalant allergens, molds and flours were negative, with the exception of D. farinae (3 mm). The prick‐to‐prick test was positive for shiitake gill (3 mm), shiitake stalk (3 mm) and dry shiitake (8 mm ps). The histamine wheal was 5–7 mm. Control prick tests with shiitake on 5 nonexposed subjects were negative. An open test was performed with shiitake on the flexor side of the upper arm. Within 20 minutes a positive reaction appeared comprising two wheals and flare reactions. Patch test with shiitake gave a strong toxic reaction in 2 days, which continued to diminish on days 3 and 4. Conclusion: Contact urticaria is the clinical skin symptom of immediate allergy, but repeated exposure may lead to protein contact dermatitis. However, our patient has not had urticaria symptoms from shiitake, although the prick‐to‐prick and open tests were positive. To our knowledge, this is the first report of protein contact dermatitis from shiitake in a patient with a positive immediate skin reaction and negative patch test result.