A 24-year-old white man presents with a 4-week history of multiple enlarging, erythematous lesions with associated itching and burning on the lower abdomen, thighs, and pubic area. He tried topical steroid cream prescribed at an outside clinic that worsened the symptoms. The patient denies a history of skin changes in family members or experiencing any systemic symptoms, including fever. He started working on a poultry farm 6 months ago. On examination, erythematous, scaly rings with central clearing and active borders are noted.
Can you diagnose this condition?
Submit your diagnosis to see full explanation.
Tinea is a name that refers to cutaneous fungal infections, and the clinical classification is based on the area of the body affected: tinea capitis (head), tinea faciei (face), tinea manuum (hand), tinea cruris (groin), tinea pedis (foot), tinea unguium (nail), and tinea corporis (body). Tinea corporis manifests as a dermatophyte infection on the body that is not present on the face, hands, groin, or feet. Tinea infections are categorized as anthropophilic, zoophilic, or geophilic based on host colonization preference and whether transmission occurs via humans, animals, or the soil.1 Tinea corporis usually develops after skin-to-skin contact, with an infected area developing on 1 of the involved individuals.2 It can also be transmitted through contact with infected farm animals or pets, and various animals are vectors for different types of fungi.3 The causative dermatophytes of tinea infection are Microsporum, Trichophyton, and Epidermophyton.1
Tinea corporis and tinea capitis are the most common infections seen in children, whereas tinea cruris, tinea pedis, and tinea unguium are more frequently seen in adolescents and adults.2 Predisposing factors for tinea infection include geographic, social, and individual health conditions. Dermatophytes thrive particularly well in hot and humid weather. As such, intertriginous areas with increased sweat production, skin breakdown, and alkaline environments provide favorable conditions for fungal proliferation.4 Social factors such as overcrowding and low socioeconomic status also predispose individuals to dermatophyte infection, and patients with diabetes mellitus, lymphoma, immunocompromised states, and Cushing syndrome are particularly susceptible.4,5
Tinea corporis, more commonly referred to as “ringworm,” manifests as a scaly rash in the shape of a ring with central clearing and a raised, erythematous border; it most commonly presents on the torso with associated pruritus. Single or multiple rings ranging from 1 to 5 cm in diameter may develop with any episode of infection. However, larger lesions can result from the convergence of these rings.2
When the diagnosis is unclear from the history and physical examination, a potassium hydroxide (KOH) preparation is often used for confirmation. The active, raised border of the annular rash should be scraped to obtain the highest number of dermatophytes. A positive scraping reveals branching, hyaline, and septate hyphae.6 False-negative tests may occur due to inadequate scrapings. Preparations of KOH are quick and simple tests that can be conducted at the bedside, and cultures are typically not necessary for a definitive diagnosis of tinea corporis. For patients with persistent symptoms, skin biopsy with periodic acid-Schiff stain may be warranted.2
Differential diagnosis of tinea corporis includes nummular eczema, psoriasis, tinea versicolor, erythema multiforme, lupus erythematosus, pityriasis rosea, and granuloma annulare. Psoriasis and eczema often are associated with a family history, and erythema multiforme and granuloma annulare typically do not present with scales on the rash. The herald patch of pityriasis rosea can mimic the ringed shape of tinea corporis, but the subsequent rash eruption in pityriasis rosea exhibits a characteristic dermatomal “Christmas tree” distribution.2,7 To distinguish between these conditions and tinea corporis, it is important to obtain a detailed history and conduct a thorough physical examination. Patients with tinea corporis are often prescribed topical steroids due to a misdiagnosis of cutaneous lupus or eczema. In such cases, the patient will experience an exacerbation of symptoms after use of topical steroids, which should prompt the consideration of tinea corporis.2
First-line treatment for tinea corporis includes topical antifungals such as azoles, allylamines, butenafine, ciclopirox, and tolnaftate. In particular, 2 allylamines — topical terbinafine and naftifine — were tested and confirmed in a randomized controlled trial for their efficacy in treating tinea corporis and tinea cruris.8 Oral antifungals such as terbinafine and itraconazole should be considered for systemic treatment in patients for whom topical treatment failed or those with immunocompromised states or extensive disease. Oral ketoconazole and nystatin are not recommended for treatment of tinea infection due to risk for hepatic toxicity and widespread resistance, respectively. Combination products containing steroids, such as betamethasone/clotrimazole, can exacerbate fungal infections. No prophylaxis for tinea corporis is needed for asymptomatic household members or close contacts.2
The patient in this case did not have any systemic symptoms indicative of a complication of tinea corporis, nor was he in an immunocompromised state. Therefore, the patient was prescribed topical terbinafine and instructed to apply this medication to the affected area for 2 weeks. At his 1-month follow-up visit, his symptoms had resolved.
Mary B. Kim, BA, and Michelle Eugene Lee, BA, at medical students at Baylor College of Medicine, in Houston, Texas. Christopher Rizk, MD, is a dermatologist with Elite Dermatology, in Houston, Texas.
1. De Hoog GS, Dukik K, Monod M, et al. Toward a novel mutilocus phylogenetic taxonomy for the dermatophytes. Mycopathologia. 2017;182(1-2):5-31.
2. Ely JW, Rosenfeld S, Seabury Stone M. Diagnosis and management of tinea infections. Am Fam Physician. 2014;90(10):702-711.
3. Kim J, Tsuchihashi H, Hiruma M, Kano R, Ikeda S. Tinea corporis due to Trichophyton erinacei probably transmitted from a hedgehog: the second case report from Japan. Med Mycol J. 2018;59(4):E77-E79.
4. Sahoo AK, Mahajan R. Management of tinea corporis, tinea cruris, and tinea pedis: a comprehensive review. Indian Dermatol Online J. 2016;7(2):77-86.
5. Oke OO, Onayemi O, Olasode OA, Omisore AG, Oninla OA. The prevalence and pattern of superficial fungal infections among school children in Ile-Ife, South-Western Nigeria. Dermatol Res Pract. 2014;2014:842917.
6. Zarei Mahmoudabadi A, Yaghoobi R. Tinea corporis due to Trichophyton simii – a first case from Iran. Med Mycol. 2008;46(8):857-859.
7. Kelly BP. Superficial fungal infections. Pediatr Rev. 2012;33(4):e22-e37.
8. El-Gohary M, van Zuuren EJ, Fedorowicz Z, et al. Topical antifungal treatments for tinea cruris and tinea corporis. Cochrane Database Syst Rev. 2014;(8):CD009992.