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A 9-year-old Hispanic boy is seen via a telehealth consultation for a rash on his back. He is currently being treated elsewhere for severe eczema with dupilumab injections and topical steroids. His parents report that his skin condition was well controlled until recently when a new rash appeared on his back. The potency of the topical steroid was increased and a short course of oral prednisone instituted but the rash continued to extend. Figure 1 is a photo of the patient that was emailed as part of the teledermatology consultation.
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Tinea incognito is an exaggerated response of a dermatophytic infection caused by the application of topical or oral corticosteroids.1 Initially, the pruritus, scaling, and erythema of the infection may improve; however, over time the fungal infection becomes more extensive and less recognizable.2 A nondescript macular rash evolves into a circular patch with raised borders. Scaling may actually decrease over time and in advanced cases the raised border may disappear.3
Tinea incognito can resemble various skin diseases such as eczema, erythema migrans, and contact dermatitis. A recent report documented tinea incognito misdiagnosed as allergic contact dermatitis to face masks.4
Diagnosis is achieved with skin microscopy of scrapings, culture and/or a skin biopsy. Treatment entails cessation of corticosteroids and the prescription of topical antifungals; more extensive cases may benefit from oral antifungals. This patient’s dermatitis resolved following 3 weeks of oral griseofulvin.
Sara Mahmood, DPM, is a podiatrist who completed a joint dermatology/podiatry fellowship and is on staff at DermDox Dermatology Centers in Pennsylvania. Stephen Schleicher, MD, is director of the DermDox Dermatology Centers, associate professor of medicine at Geisinger Commonwealth Medical College, and clinical instructor of dermatology at Arcadia University and Kings College.
References
1. Arenas R, Moreno-Coutiño G, Vera L, Welsh O. Tinea incognito. Clin Dermatol. 2010;28(2):137-139. doi:10.1016/j.clindermatol.2009.12.011
2. Dhaher S. Tinea incognito: clinical perspectives of a new imitator. Dermatol Reports. 2020;12(1):8323. doi:10.4081/dr.2020.8323
3. Paloni G, Valerio E, Berti I, Cutrone M. Tinea incognito. J Pediatr. 2015;167(6):1450-e2. doi:10.1016/j.jpeds.2015.08.062
4. Cunningham EP, Carter NF. Tinea incognito “mask”erading as allergic contact dermatitis due to COVID-19 facial covering in children. Pediatr Dermatol. 2022 Feb 4. doi:10.1111/pde.14911
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