Shiitake (Lentinula edodes) dermatitis

Shiitake an edible asian mushroom nowadays becomes popular in european cooking, too. Allergic diseases to shiitake occur as contact dermatitis, alveolitis or asthma. Consuming of raw shiitake causes toxicodermia. Along with this disease papules develop. The polysaccharide lentina probably is the responsible toxin. Within seven months, we found three patients developing skin lesions after eating this mushroom. A 45 years old patient who often prepared and consumed meals containing shiitake, showed recurrent erythematous papules on his face. A prick to prick test with a shiitake mushroom showed an immediate converting into a delayed reaction. Two other patients developed skin eruptions after eating raw shiitake. One of them had eaten fried shiitake before without any problems. Prick to prick tests with Shiitake tamed out to be negative in both cases. At the side of testing, 24 hrs later a delayed reaction with severely itching papules developed. The first case is supposed to be an allergic reaction whether the two other cases may rather be a toxicodermia, because of their history and clinical symptoms. However, the positive skin tests in these two cases would suggest other possible mechanisms. Further studies are necessary to clarify theses different phenomenon.