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Tinea corporis 1_0312DermDx
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Tinea corporis 2_0312DermDx
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Tinea corporis 3_0312DermDx
A 38-year-old man presents complaining of itchy red patches on his back that have been present for months. His primary medical doctor initially prescribed clotrimazole antifungal cream for tinea corporis. When the lesions did not improve, the patient was given triamcinolone topical corticosteroid cream to treat a presumed eczema.
The triamcinolone relieved the itchy sensation, but the red patches continued to expand. The patient is overweight, but otherwise healthy. He uses no other medications. He is sexually active with women and has had two partners in the past year. Family history is noncontributory.
On physical exam, the patient is overweight, but in no acute distress. His exam is significant only for large erythematous annular patches with peripheral pustules and minimal scale on his back. What’s your diagnosis?
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The term “tinea” indicates an infection of the stratum corneum, the most superficial layer of the skin, with a species of fungus known as dermatophytes. The common term for tinea is “ring worm.”
Dermatophyte infections have various names based on body location, with tinea corporis representing a dermatophyte infection of the trunk and extremities. Names for infections affecting other parts of the body are as follows: hands, tinea mannum; feet, tinea pedis; groin, tinea cruris; face, tinea facei; scalp, tinea capitis; and nails, tinea unguinum.
Tinea corporis most commonly presents as round, sharply demarcated patches, sometimes with central clearing and frequently with an inflammatory or “active border” consisting of scale and pustules. Patients may complain of itching or burning.In the setting of topical corticosteroid use, scale and pustules are absent or subtle, and the patient may be entirely asymptomatic. Notably, while topical corticosteroids may mask scale, pustules and pruritus, they also exacerbate the infection.1, 2
The most common cause of tinea corporis is Trychophyton rubrum followed by Trychophyton mentagrophytes. Tinea corporis is spread from human-to-human, soil-to-human or animal-to-human. Patients at risk for tinea corporis may have a personal history of (or a close contact with) tinea capitis, tinea pedis or tinea unguinum.
Other risk factors include close contact with domestic animals, immunosuppression and recreational or occupational exposure – including exposure to locker rooms and military housing or participating in wrestling.1, 2
Diagnosis
Diagnosis is based on the clinical appearance of annular patches with an inflammatory border. When the diagnosis is in doubt, examining skin scrapings under a microscope will demonstrate fungal elements. Skin biopsies are occasionally required. Additionally, clinicians may culture scale to identify the particular microorganism causing the infection.
Tinea versicolor consists of hyper or hypopigmented asymptomatic, noninflammatory (i.e. no pustules, minimal scale) lesions, and is easily distinguished from tinea corporis.1, 2
Treatment
Topical antifungals such as terbinifine or clotrimazole are considered first line therapy for limited disease. However, in practice we find that many patients require systemic oral antifungal therapy with medications including terbinafine or itraconazole. Limited tinea corporis infections require a two-week course of oral terbinafine or a one-week course of oral itraconazole.
A full body skin exam is warranted in all cases to identify other body areas with tinea infection. Tinea nail infections, for example, serve as reservoirs for reinfection and require prolonged systemic therapy.
In this case, the patient also had thickened yellowish dystrophic toenails with subungual debris, clinically indicative of tinea unguinum. He was treated with 12 weeks of oral terbinafine for tinea unguinum. After week two of therapy the lesions on his trunk had completely cleared.
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.
References
1. Bolognia J, Jorizzo JL, Rapini RP. “Chapter 76: Fungal Diseases.” Dermatology. 2008; Mosby/Elsevier; St. Louis, Mo.
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