Tinea Cruris

(Jock Itch)

By Denise M. Aaron, MD, New, Dartmouth-Hitchcock Medical Center

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Tinea cruris is a dermatophyte infection of the groin.

Tinea cruris is a dermatophytosis that is commonly caused by Trichophyton rubrum or T. mentagrophytes. The primary risk factors are associated with a moist environment (ie, warm weather, wet and restrictive clothing, obesity causing constant apposition of skinfolds). Men are affected more than women because of apposition of the scrotum and thigh.

Typically, a pruritic, ringed lesion extends from the crural fold over the adjacent upper inner thigh. Infection may be bilateral. Lesions may be complicated by maceration, miliaria, secondary bacterial or candidal infection, and reactions to treatment. In addition, scratch dermatitis and lichenification can occur. Recurrence is common because fungi may repeatedly infect susceptible people or people with onychomycosis or tinea pedis, which can serve as a dermatophyte reservoir. Flare-ups occur more often during summer.

Diagnosis

Clinical evaluation
Sometimes potassium hydroxide wet mount

Differential diagnosis of tinea cruris includes

Scrotal involvement is usually absent or slight; by contrast, the scrotum is often inflamed in candidal intertrigo or lichen simplex chronicus. If the appearance is not diagnostic, a potassium hydroxide wet mount is helpful.

Treatment

Topical antifungal cream, lotion, or gel

Antifungal choices include terbinafine, miconazole, clotrimazole, ketoconazole, econazole, naftifine, and (uncommonly) ciclopirox applied bid for 10 to 14 days.

Itraconazole 200 mg po once/day or terbinafine 250 mg po once/day for 3 to 6 wk may be needed in patients who have refractory, inflammatory, or widespread infections.

Last full review/revision April 2017 by Denise M. Aaron, MD