Shiitake dermatitis: experience of the Poison Control Centre Network in France from 2014 to 2019

Objective Shiitake mushrooms (Lentinus edodes) are an edible fungus, initially grown in Japan and China that are increasingly marketed in Europe. We previously presented 15 shiitake dermatitis cases reported to Poison Control Centres (PCCs) in France from January 2000 to December 2013. The aim of this study was to describe changes in the number of shiitake dermatitis cases since 2014, and to better describe the clinical characteristics and risk factors of this reaction. Case series This observational study is a retrospective review of cases in the French PCCs database between 1 January 2014 and 31 December 2019. Out of 125 shiitake exposures, we identified 59 cases of dermatitis: sex ratio of 1.80 M/F; ages ranging from 19 to 69 years (median: 39 years). Dermatitis occurred after raw or undercooked shiitake consumption (e.g., from the wok, in soup, or on pizza). The rash appeared 1-168 h (median: 48 h) after shiitake ingestion. Linear, erythematous, urticarial papules and plaques developed across the trunk, arms, and legs within a few hours and persisted for 1-40 d (median 10 d). The amount of shiitake eaten (low vs. medium vs. high) significantly increased the duration of dermatitis (median days 4 vs. 7 vs. 15, respectively; p = .007). In all, 38 patients received corticosteroids, antihistamine drugs, or both without demonstrated benefit. All patients made a complete recovery. Conclusions The mechanism of shiitake dermatitis is thought to involve lentinan, a heat-labile polysaccharide component. Inadequate cooking clearly seems to be a driver of the occurrence of shiitake dermatitis. This study highlighted a dose-dependent response, suggesting a partial toxic mechanism or a th1-type hypersensitivity mechanism. Treatment is focused on symptom management. Health professionals and the general population should be aware of both the risk associated with inadequately cooked shiitake consumption and the favourable prognosis of this still poorly known toxic dermatitis.