Shiitake dermatitis (SD) is correlated with the ingestion of raw or undercooked shiitake mushrooms (SMs) and is more common in countries where SMs are habitually eaten. The condition was first reported in Japan by Nakamura in 19771 and has since been recorded worldwide. The associated reports are rare in the domestic. This disease is characterized by intensely pruritic isolated or grouped papules or papulovesicles with whiplash-striped, infiltrated erythema that arise in a pattern consistent with the Köbner phenomenon because of stripe-like scratching, thus differing the lesions from the immediate onset of dermographism.1
SD is not a common disease in China, and only two cases were reported in Wanfang database by June 3rd, 2018.2-3 We herein present a case of SM-induced flagellate dermatitis in a 28-year-old man with possible mechanisms in order to enhance awareness of SD in Chinese clinical doctors.
A 28-year-old nonatopic, healthy man was observed in Beijing Ditan Hospital because of a 2-day history of an extensive pruritic skin eruption with no other symptoms. He denied any exposure to medications or plants. In particular, he had no fever, muscle weakness, lymphadenopathy, or other cutaneous lesions such as Gottron's sign, nor did he have symptoms indicative of systemic autoimmune disease.
Physical examination revealed linear groups of erythematous papules in a symmetrical flagellate pattern mainly on his back and limbs (Fig. 1). He had no mucosal involvement or dermatographia. However, he recalled having eaten SMs in the dining hall of his workplace 4 days before the onset of this eruption.
Findings from routine blood tests, including a complete blood cell count, liver and renal function tests, an eosinophil count, and the C-reactive protein level, were normal.
Given the characteristic clinical presentation, the patient was diagnosed with SD. The eruption resolved about 5 days later with an oral antihistamine combined with a topical steroid (hydrocortisone butyrate ointment) and calamine lotion.
SM is currently the second most commonly produced edible mushroom in the world. It is typically grown in East Asia and is used in traditional Asian medicine and cuisine. SD is also termed shiitake flagellate dermatitis, flagellate mushroom dermatitis, or shiitake toxicoderma, and was first described by Nakamura in 1977. In 1992, Nakamura reported 51 patients with SD during April 1974 to April 1991.1 It usually presents as a linear, erythematous eruption resembling scratches or whiplash marks. SD classically manifests 12 hours to 5 days after the ingestion of raw or undercooked SMs.1,4 There is a delay between ingestion and lesion eruption, which can complicate the diagnosis. The lesions typically arise in the trunk and, in decreasing order, followed by the extremities, neck, face, and head.1 Involvement of the mucous membranes or other organs has not been reported. Additional cases were reported in Europe,5 South America,6 and North America.7 Flagellate mushroom dermatitis induced by other mushrooms such as Boletus mushroom5 and Auricularia auricula-judae8 has also been reported.
The mechanism underlying SD has not been fully studied. The pathologic mechanism may be associated with the toxicity of lentinan, a thermolabile polysaccharide that induces the production of interleukin-1 and causes vasodilation and rash.6 This substance is broken down by heat; therefore, the dermatitis only occurs following ingestion of raw or lightly cooked SMs. Recent reports show that nearly half of patients develop flagellate dermatitis after eating thoroughly cooked SMs.9 Hence, the precise pathogenesis of SD cannot be fully explained simply by toxicity of lentinan.
Skin lesions similar to those seen in patients with SD have also been reported as a cutaneous adverse effect of chemotherapy with bleomycin, peplomycin, doxorubicin, and bendamustine (these lesions usually involve the mucous membranes and heal with hyperpigmentation) or in the context of dermatologists and adult-onset Still's disease.10 No specific biopsy or laboratory findings of SD have been reported.1 SD is self-limiting, and usully lasts from 2 days to 6 weeks with an average disease course of 8.5 days.1 Treatment is symptomatic with oral non-sedating antihistamines, and topical corticosteroids, and a short course of oral corticosteroids is recommended for severe cases.
The case reported herein was a typical form of SD, which is relatively rare in Chinese literature. This small number of reports is probably related to the lack of understanding of the disease or the differences in cooking methods. Therefore, dermatologists need to be vigilant about this disease to avoid misdiagnosis and delayed treatments.
. Nakamura T. Shiitake (Lentinus edodes) dermatitis. Contact Dermatitis 1992;27(2):65–70.
. Shi W, Zhang JW, Xie HF, et al Two cases of shiitake dermatitis. Chin J Dermatol 2014;47(3):208–209. doi: 10.3760/cma.j.issn.0412-4030.2014.03.014. (In Chinese).
. Dai J. A case of flagellate dermatitis. J Pract Dermatol 2015;8(2):159doi: 10.11786/sypfbxzz.1674-1293.20150230. (In Chinese).
. Santos N, Silva PM, São BMA. A case of flagellate dermatitis after ingestion of shiitake mushrooms. J Allergy Clin Immunol Pract 2018;6(2):647–648. doi: 10.1016/j.jaip.2017.08.030.
. Molin S, Summer B, Thomas P, et al Boletus dermatitis: a new variant of flagellate erythema. Ann Allergy Asthma Immunol 2015;115(3):254–255. doi: 10.1016/j.anai.2015.06.028.
. Mendonça CN, Silva PM, Avelleira JC, et al Shiitake dermatitis. An Bras Dermatol 2015;90(2):276–278. doi: 10.1590/abd1806-4841.20153396.
. Netchiporouk E, Pehr K, Ben-Shoshan M, et al Pustular flagellate dermatitis after consumption of shiitake mushrooms. JAAD Case Rep 2015;1(3):117–119. doi: 10.1016/j.jdcr.2015.02.010.
. Lang N, Enk AH, Toberer F. Streaky, whiplash-like erythema and succulent papules: flagellate dermatitis following consumption of Auricularia auricula-judae. J Dtsch Dermatol Ges 2016;14(3):303–304. doi: 10.1111/ddg.12769.
. Czarnecka AB, Kreft B, WCh M. Flagellate dermatitis after consumption of shiitake mushrooms. Postepy Dermatol Alergol 2014;31(3):187–190. doi: 10.5114/pdia.2014.40929.
. Lim D, Aussedat M, Maillet-Lebel N, et al Flagellate dermatitis in a child most likely secondary to doxorubicin. Pediatr Dermatol 2017;34(5):e257–e259. doi: 10.1111/pde.13234.