Allergy and toxicodermia from shiitake mushrooms.

Skin and respiratory symptoms developed within 2 months of exposure in a patient involved in the commercial production of shiitake mushrooms. A diagnosis of contact urticaria and allergic contact dermatitis from shiitake mushrooms was confirmed by prick and patch tests. The respiratory symptoms, their timing, the presence of precipitating IgG antibodies to shiitake spores and increased amounts of inflammatory cells and T lymphocytes in bronchoalveolar lavage indicated allergic alveolitis (mushroom worker's disease). A generalized exanthem developed in a second patient after eating raw shiitake mushrooms. Reactions to prick and patch tests with shiitake mushrooms were negative. The skin eruption in this patient corresponded to the previously reported shiitake-induced toxicodermia.