Clinics in Dermatology (2010) 28, 137–139

Tinea incognitoRoberto Arenas, MDa,⁎, Gabriela Moreno-Coutiño, MDa,Lucio Vera, DrSc b, Oliverio Welsh, MDb

aMycology Section, Department of Dermatology, “Dr. Manuel Gea Gonzalez” General Hospital,Calzada de Tlalpan 4800, 14080 México, DF, MéxicobDepartment of Dermatology, Dr. Jose Eleuterio Gonzalez University Hospital, Monterrey, México

Abstract Tinea incognito was first described 50 years ago. It is a dermatophytic infection with a clinicalpresentation modified by previous treatment with topical or systemic corticosteroids, as well as by thetopical application of immunomodulators such as pimecrolimus and tacrolimus. Tinea incognito usuallyresembles neurodermatitis, atopic dermatitis, rosacea, seborrheic dermatitis, lupus erythematosus, orcontact dermatitis, and the diagnosis is frequently missed or delayed.© 2010 Published by Elsevier Inc.

Introduction

Tinea corporis is clinically defined as patches of scalyerythema with a slightly elevated border. This picture isrepresentative of most lesions affecting glabrous skin. Oneof the diagnostic challenges in tinea corporis and tineacapitis is identifying those cases that have been previouslymistreated by self-medication or secondary to the use oftopical and systemic immunosuppressants, such as steroidsand immunomodulators.

The term tinea incognito was originally described in 1968by Ive and Marks in 14 patients with a dermatophyticinfection that had an atypical clinical presentation caused byprevious treatment with steroids. This occurred in the 1960safter the introduction of these drugs for the topical treatmentof diverse dermatologic diseases. Since then, other cases havebeen described with the topical application of pimecrolimus

⁎ Corresponding author. Tel.: + 55 4000 3058; fax: +55 4000 3058.E-mail address: rarenas98@hotmail.com (R. Arenas).

0738-081X/$ – see front matter © 2010 Published by Elsevier Inc.doi:10.1016/j.clindermatol.2009.12.011

and tacrolimus, although topical or systemic use ofcorticosteroids continues to be the most common cause.

Over-the-counter access to steroids and other immuno-suppressants in some countries, as well as the increase inmedications containing steroids, makes tinea incognito morelikely, and therefore, the diagnosis is frequently missed ordelayed. These drugs suppress the normal cutaneous immuneresponse to dermatophytes, thus enhancing the developmentof fungal superficial infections.1-6

Some physicians, particularly nondermatologists, pre-scribe combinations of steroids and antifungals, such asbetamethasone and clotrimazole, in which the betamethasonehas a dominant effect over the antifungal agent, thusexacerbating superficial dermatophytosis.7

As with other dermatophytosis, these infections mayinvolve patients of any age or sex. All areas may be affected,but the face and arms are more prevalent; the feet are rarelyaffected by this condition, because tinea pedis is anexceptionally missed diagnosis.

Clinically, these lesions have a less raised margin and areless scaly than common dermatophytosis. They tend to be

Fig. 1 Tinea incognito on the upper part of the back.

138 R. Arenas et al.

pustular, pruritic, extensive, and erythematous and maymimic other skin diseases (Figure 1). Another clinical formthat can be confused with bacterial infections or prurigo istrichophytic granuloma (Majocchi granuloma), which ismore commonly found on the legs of women. The funguscan be inoculated by shaving the legs, and a contributingfactor is the use of corticosteroid creams. It is common tofind tinea pedis or onychomycosis in these cases.

The main differential diagnosis depends on the affectedarea. In the face, the lesions may resemble neurodermatitis,atopic dermatitis, rosacea, seborrheic dermatitis, lupuserythematosus, or contact dermatitis. A recent studyreported that facial tinea incognito is frequently associatedwith tinea pedis or onychomycosis in toenails, or both.8 Inthe glabrous skin, the main differential diagnosis isimpetigo, purpura, lichen planus, psoriasis, erythemamigrans, drug eruptions, Sweet neutrophilic dermatosis,contact dermatitis, discoid lupus, and tuberculoid leprosy.

A 15-year survey from Italy reported 200 cases of tineaincognito. Of these, 9% had folliculitis, and dermatophytidswere uncommon. The source of infection was human-to-human transmission. Among elderly patients, the misdiag-nosis of dermatitis in the legs associated with venous failure,was reported as a common cause of tinea incognito. Up to40% in this series required systemic steroids for treatment ofskin and nondermatologic diseases. For this reason, theauthors underlined the importance of looking for nailalterations, which can indicate onychomycosis, especiallyin chronic forms of tinea incognito.

The clinical history is fundamental, because the clinicalappearance may be confusing. The definitive diagnosis mustbe attained in a mycology laboratory or by an expert indermatomycology using direct examination with potassiumhydroxide, which demonstrates fungal structures. Thespecies must be also identified by culture. Occasionally,the diagnosis is made by histopathology with hematoxylinand eosin and periodic acid-Schiff stains.9,10

The main etiologic agents reported are Trichophytonrubrum, T mentagrophytes, Epidermophyton floccosum,Microsporum canis, M. gypseum, T violaceum, and T erinacei.The first two are most commonly isolated when the face isinvolved.11-33 Fluorinated corticosteroids were implicated in ahospital dermatophytosis outbreak by E floccosum.34

These dermatophytoses usually require systemic treat-ment with oral antifungal agents. Terbinafine, itraconazole,and fluconazole have been shown to be superior to treatmentwith griseofulvin, because they accumulate in the skin.Therapy is generally indicated for 2 weeks, but the clinicaland mycologic responses will determine the definite durationof treatment.35

In renal transplant patients, an uncommon presentation ofatypical tinea is dermatophytic granuloma. The lesionsevolve into chronic dermatophytosis that can clinicallyresemble vasculitis.1

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