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A characteristic rash caused by Shiitake mushrooms – An emerging concern?

Summary

Eating raw or undercooked Shiitake mushrooms can cause a distinctive whip-like rash in some people called Shiitake mushroom dermatitis. This dramatic rash appears 2-5 days after consumption but is not dangerous and goes away on its own in 10-14 days. The condition is caused by a compound called Lentinan that breaks down when mushrooms are cooked at higher temperatures, so properly cooking Shiitake mushrooms prevents the reaction.

Background

Shiitake mushrooms (Lentinus edodes) are widely consumed worldwide and have been studied for therapeutic properties including antitumor and antimicrobial effects. Consumption of raw or undercooked Shiitake mushrooms can lead to a dramatic rash known as Shiitake mushroom dermatitis or flagellate dermatitis.

Objective

To report and discuss a case of Shiitake mushroom dermatitis that developed after consumption of mushroom tea and to raise awareness among clinicians about this emerging concern with increasing Shiitake mushroom consumption.

Results

Patient presented with characteristic erythematous curvilinear streaks with cross-hatched pattern over trunk and limbs without systemic symptoms. Diagnosis of Shiitake mushroom dermatitis was made based on clinical presentation and history. The rash resolved completely over 2 weeks with topical corticosteroids.

Conclusion

Shiitake mushroom dermatitis is a self-limiting idiosyncratic reaction caused by Lentinan, a thermolabile polysaccharide in raw or undercooked mushrooms. Clinicians should recognize this condition and distinguish it from anaphylactic reactions. Affected individuals should avoid undercooked Shiitake mushrooms in the future.
  • Published in:Clinical Case Reports,
  • Study Type:Case Report,
  • Source: PMID: 34194772, DOI: 10.1002/ccr3.4181
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