Photo Quiz

Severely Pruritic, Whip-like Dermatitis


Am Fam Physician. 2021 Feb 15;103(4):243-244.

A 36-year-old patient presented with fever, headache, cough, sore throat, and a new widespread pruritic rash that began 48 hours earlier. The patient had no significant medical or surgical history and was not taking any new medications. The patient had no change in diet, no exposures to chemicals, and no symptomatic contacts.

Examination revealed a maculopapular, erythematous rash with whip-like extensions (Figure 1). The rash was most prominent on the lower abdomen, buttocks, and thighs but extended to the extremities and face, including the vermilion border and eyelids. The rash spared the mucosal surfaces, palms, and soles.




Based on the patient's history and physical examination findings, which one of the following is the most likely diagnosis?

  • A. Bleomycin-induced flagellate dermatitis.

  • B. Contact dermatitis.

  • C. Dermatomyositis.

  • D. Herpes zoster (shingles).

  • E. Shiitake flagellate dermatitis.


The answer is E: shiitake flagellate dermatitis. The patient revealed that they had consumed raw shiitake mushrooms two days before symptom onset.

Shiitake flagellate dermatitis was first described in susceptible individuals after ingesting raw or undercooked shiitake mushrooms but has more recently been reported with fully cooked mushrooms and with extract.1,2 The exanthem is thought to be secondary to lentinan, a heat-labile protein present in undercooked mushrooms. The exact etiology is unclear, but lentinan is thought to increase secretion of inflammatory cytokine interleukin-1, resulting in vasodilation and hemorrhage.3

The condition develops 24 to 48 hours after

Address correspondence to Daniel Jason Frasca, DO, at Reprints are not available from the authors.

Author disclosure: No relevant financial affiliations.


show all references

1. Chu EY, Anand D, et al. Shiitake dermatitis. Cutis. 2013;91(6):287–290....

2. Kopp T, Mastan P, Mothes N, et al. Systemic allergic contact dermatitis due to consumption of raw shiitake mushroom. Clin Exp Dermatol. 2009;34(8):e910–e913.

3. Fang S, Bajoghli A, Bajoghli M. Shiitake mushroom-induced flagellate dermatitis. Ann Allergy Asthma Immunol. 2017;119(5):462–463.

4. Stephany MP, Chung S, Handler MZ, et al. Shiitake mushroom dermatitis: a review [published correction appears in Am J Clin Dermatol. 2016; 17(6):709]. Am J Clin Dermatol. 2016;17(5):485–489.

5. Ribeiro CS, Sodré CT, Ramos-E-Silva M. Flagellate dermatitis by shiitake mushroom. Case Rep Dermatol. 2019;11(2):220–225.

6. Ko SY. Flagellate dermatitis. Clin Pract Cases Emerg Med. 2017;1(1):63–64.

7. Mowad CM, Nguyen TV, Elenitsas R, et al. Bleomycin-induced flagellate dermatitis. Br J Dermatol. 1994;131(5):700–702.

8. Arseculeratne G, Berroeta L, Meiklejohn D, et al. Bleomycin-induced “flagellate dermatitis.” Arch Dermatol. 2007;143(11):1461–1462.

9. Mendonça FM, Márquez-García A, Méndez-Abad C, et al. Flagellate dermatitis and flagellate erythema. Int J Dermatol. 2017;56(4):461–463.

10. Lachapelle JM. Allergic contact dermatitis: clinical aspects. Rev Environ Health. 2014;29(3):185–194.

11. Nousari HC, Ha VT, Laman SD, et al. “Centripetal flagellate erythema.” J Rheumatol. 1999;26(3):692–695.

12. Sena P, Gianatti A, Gambini D. Dermatomyositis: clinicopathological correlations. G Ital Dermatol Venereol. 2018;153(2):256–264.

13. Bolton L. Herpes zoster (shingles). Wounds. 2018;30(5):144–146.

This series is coordinated by John E. Delzell Jr., MD, MSPH, associate medical editor.

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