Abstract Number: 1

Shiitake dermatitis after ‘detoxification’ diet

K. Allnutt1, A. Chong1

Meeting: 2019 Dermcoll

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A healthy 30-year-old Caucasian woman presented three days after starting on a “detoxification” diet with a widespread, intensely pruritic eruption on her neck, trunk and limbs characterised by papules and erythematous linear streaks. She was also feeling generally unwell. Further questioning revealed she had consumed raw shiitake mushrooms for the first two days of the diet. She was diagnosed with shiitake dermatitis and was started on oral fexofenadine 180mg bd, prednisolone at 25mg daily and bethamethasone diproprionate 0.05% ointment bd. She was also advised to avoid eating raw or undercooked shiitake mushrooms. There was significant improvement on review five days after the initial consultation. Shiitake dermatitis is a rare dermatitis which presents as a pruritic erythematous eruption with papules in a characteristic linear (flagellate) pattern, resembling whiplash marks, typically distributed over the trunk, extremities and neck. Shiitake dermatitis is thought to be caused by a toxic reaction to lentinan, a thermolabile polysaccharide found in the mushroom cell wall. The diagnosis is clinical with a history of recent ingestion of raw or partially cooked shiitake mushrooms. Shiitake mushrooms are now the second most commonly consumed mushroom worldwide and raw mushrooms are part of some “detoxification” diets. Shiitake dermatitis should be considered as a differential for flagellate dermatitis, especially in the setting of certain diets when raw mushrooms are consumed.