Clinico-epidemiological and Mycological Aspects of Tinea Incognito in Iran: A 16-Year Study

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Background: Tinea incognito is a dermatophytic infection in which topical or systemic steroids have modified the clinical appearance of the mycosis and mimicking other skin diseases. Objectives: A large retrospective study was carried out to identify the clinical aspects and type of dermatophytes involved in tinea incognito cases in Iran during 1993-2008. Patients: Out of 6325 subjects suspected to have dermatophytoses, 56 patients (29 males, 27 females, mean age 32.6 years) were affected with tinea incognito. Methods: The causative agents were identified macroscopically and microscopically after the clinical samples were subjected to potassium hydroxide examination and culture isolation. Results: The most common type of infection was tinea corporis (32.1%), which significantly affected male patients. The prevalence of the other tineas in decreasing order was as follows: tinea faciei (26.8%), tinea cruris (14.3%), tinea manuum (12.5%), tinea pedis (8.9%), and tinea capitis (5.4%). The clinical features were to some extent diverse, ranging from eczema-like, seborrhoeic dermatitis-like, pyoderma-like and folliculitis to alopecia on scalp, trunk and limbs. Trichophyton verrucosum was the most frequently isolated species representing 33.9% of isolates, followed by T.mentagrophytes (28.6%), T. rubrum (12.5%), Epidermophyton floccosum (10.7%), Microsporum canis (8.9%), T. violaceum (3.6%), and T. schoenleinii (1.8%). Conclusion: To the best of our knowledge, this is the first broad investigation dealing with tinea incognito in Iran. The etiological agents of tinea incognito in Iran are consistent with those of the general population.