Tinea cruris, also known as jock itch, is a fungal infection involving the genital, pubic, perineal, and perianal skin caused by pathogenic fungi known as dermatophytes.

Tinea cruris is commonly caused by Trichophyton rubrum or T. mentagrophytes.

Several risk factors have been identified that predispose an individual to tinea cruris, including excessive perspiration, occlusive clothing, improper hygiene, obesity, diabetes mellitus, topical steroid use, immunocompromise, and lower socioeconomic status.

Men are affected more than women because of apposition of the scrotum and thigh.

Tinea cruris clears with appropriate treatment in 80–90% of cases. However, recurrence is common, especially if predisposing factors are not addressed or antifungal treatment is stopped before mycological cure.

CLINICAL FEATURES

Patients with tinea cruris present complaining of a pruritic rash involving the groin. The area may be irritated and painful if maceration is present, and secondary infections may result in inflammation and discomfort. 

Duration of symptoms, previous occurrences, similar rashes in other locations, and past treatments should be elucidated. Individuals should be questioned about any history of diabetes, immunocompromise, renal disease, or hepatic dysfunction. 

Clinicians should inquire about excessive sweating, wardrobe changes, and personal hygiene habits.

A review of the patient's environmental and occupation exposures, including people, pets, animals, and contaminated soil, may be contributory.

On physical examination, an erythematous, scaly, annular plaque with a raised leading edge and central clearing can be visualized, extending anywhere from the groin, upper thigh, and perineum to the perianal region.

INVESTIGATIONS

In most cases, tinea cruris can be diagnosed clinically; however, several tests exist to investigate a rash of the groin with unknown etiology. 

Potassium hydroxide (KOH) preparations, skin biopsy with periodic acid-Schiff (PAS) stain, and fungal cultures on Sabouraud’s agar media can be utilized when the diagnosis is in question or the case of recurrent or recalcitrant episodes.

TREATMENTS

General and preventative measures

• Careful toweling after washing to avoid transfer of fungi from the feet
• Loose fitting clothing
• Treatment of triggers such as hyperhidrosis or obesity
• Topical antifungal powder after bathing

Specific measures

• Topical antifungal medication such as imidazoles or terbinafine
• Oral antifungal medication for extensive or recalcitrant infection, particularly in immunosuppressed patients eg, griseofulvin, terbinafine, itraconazole
• Treatment of tinea at other sites such as tinea pedis or tinea unguium
• Mild topical steroid can be used short-term to reduce itch, but is not appropriate as a monotherapy or long-term use
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