Tinea cruris

Tinea cruris or “jock itch” is a superficial infection of the groin and surrounding skin caused by dermatophytes (1).

Tinea in the groin produces a brownish red rash with pustules and vesicles at the active borders (2).

• most commonly affect the medial side of the thighs and inguinal folds bilaterally
• usually spares the penis and scrotum (3)

It occurs

• almost exclusively in young men (specially in obese adult men)
• rarely in children (1)

Associated tinea pedis may often be a source of infection. Most common causative pathogen is Trichophyton rubrum (2).

There is often spread of the infection from the groins to involve the lower abdomen, scrotum and buttocks. Often patients complain of burning and pruritus (2).

Diagnosis can be confirmed by culture. Wood's light is unhelpful in diagnosing this condition (2).

Key points (4):

• most cases:
  • use topical terbinafine as fungicidal, treatment time shorter and more effective than with fungistatic imidazoles or undecenoates.If candida possible, use topical imidazole
• if intractable, or scalp:
  • send skin scrapings, if infection confirmed:
    • use oral terbinafine or itraconazole
• scalp:
  • oral therapy, and discuss with specialist

Reference:

• (1) Nadalo D, Montoya C. What is the best way to treat tinea cruris? JFP 2006;55(3)
• (2) Hainer BL. Dermatophyte infections. AFP 2003;67(1)
• (3) Weinstein A, Berman B. Topical treatment of superficial tinea infections. AFP 2002;65(10)
• (4) Public Health England (June 2021). Managing common infections: guidance for primary care