Clinical Challenge: Annular Patch with Serpiginous Borders

Tinea faciei is an infection of the face by a group of fungus called dermatophytes. Dermatophyte infections are commonly known as "ringworm." Dermatophytes include three genera of fungi that have the ability to invade keratinized tissue such as hair, skin,...

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Tinea faciei is an infection of the face by a group of fungus called dermatophytes. Dermatophyte infections are commonly known as “ringworm.” Dermatophytes include three genera of fungi that have the ability to invade keratinized tissue such as hair, skin, and nails. These three genera are microsporum, trichophyton, and epidermophyton.

Clinically, tinea faciei may have classic features of dermatophytoses, such as scale, an annular configuration, and pustules in the border. However, tinea faciei is frequently misdiagnosed. The typical annular rings are often absent, and due to the photosensitive nature of the lesions, clinicians often misdiagnose patients with lupus erythematosus.

Tinea faciei most commonly present as erythematous, slightly scaling plaques, with indistinct serpiginous borders at the periphery of the lesions. If the patient is seen after the use of topical corticosteroids, fungal folliculitis may be a confounding presentation. Because of the clinical difficulty of diagnosing tinea faciei, a high index of suspicion is required.

Tinea faciei is most commonly caused by Trichophyton rubrum, Trichophyton mentagrophytes, or Microsporum canis. In hog farmers, tinea faciei is frequently caused by Microsporum nanum. 

Tinea faciei can be diagnosed clinically by the distinctive annular and serpiginous patches on the face.  The diagnosis may be confirmed by a potassium hydroxide preparation or fungal culture. Sometimes a biopsy is required. 

First-line treatment for uncomplicated, localized tinea faciei without folliculitis includes topical antifungals such as terbinafine. When topical steroids have been inappropriately prescribed, fungal folliculitis is often present. Tinea faciei with fungal folliculitis or tinea faciei with an associated widespread infection requires oral medication for treatment.

Christopher Chu is a medical student at Baylor College of Medicine.

Adam Rees, MD, is a graduate of the University of California Los Angeles School of Medicine and a resident in the Department of Dermatology at Baylor College of Medicine in Houston.