Shiitake mushroom (Lentinus edodes) ingestion can induce a clinically distinctive dermatitis. Most cases have appeared in Japan and, recently, in Europe. We describe a patient from the United States who developed shiitake dermatitis and demonstrated k€ oebnerization on rechallenge.
Case historyA 28-year-old man presented with a 1-day history of an extensive pruritic linear rash. He had eaten four to five steam-cooked shiitake mushrooms (originally dried) approximately 10 hours before rash onset. He had eaten shiitake mushrooms two weeks before without development of a rash. On exam, he had erythematous, edematous linear plaques on his trunk, upper extremities, and neck ( Fig. 1). Based on clinical findings, he was diagnosed with shiitake flagellate dermatitis. The patient's rash resolved in one week with a prednisone taper (40 mg for four days and taper by 10 mg every four days thereafter) and topical clobetasol. No antihistamines were given.Six months later, he underwent rechallenge with two raw shiitake mushrooms. DuoDerm â patches were placed on his right flank to prevent scratching in an area where lesions had been present during the initial outbreak. Four hours after ingesting the mushrooms, he experienced flushing and generalized pruritus (without rash) that resolved in two hours. He wrote his initials on his left flank with his finger during this pruritic period. Approximately 44 hours after eating the mushrooms, he developed a pruritic rash in the area where he had written his initials (Fig. 2). Additionally, erythematous, edematous linear plaques were present on the upper back, chest, shoulders, and neck. No lesions were present under the DuoDerm â on his right flank (Fig. 1). Two lesional punch biopsies were obtained; one was from within a k€ oebnerized initial area, the other from a flagellate erythematous plaque on the right shoulder.Both biopsies demonstrated superficial perivascular lymphocytic infiltrates with occasional eosinophils. The infiltrate in the deliberately k€ oebnerized lesion extended into the mid-dermis. The other biopsy also showed mild acanthosis and spongiosis with focal lymphocyte exocytosis. Recurrent rash was also treated successfully with identical prednisone taper and topical clobetasol.Several weeks later, he agreed to eat fully cooked shiitake mushrooms. Neither rash nor pruritus developed.
Discussion
Total testosterone in men with erectile dysfunction who are younger than 45 years should be drawn as close to 7 a.m. as possible because a statistically and clinically relevant decrease in testosterone will occur during the course of the day. Men older than 45 years with erectile dysfunction can have total testosterone drawn at any time before 2 p.m. without misleading results.
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