VisualDx - Diagnosis Details - Male Adult Anogenital: Tinea Cruris

110.3 – Dermatophytosis of the groin and perianal area

Tinea cruris (jock itch) is a superficial fungal infection of the skin most commonly caused by Trichophyton rubrum or other dermatophytes. Tinea cruris manifests as a symmetric erythematous rash in the inner thighs and the crural folds. It rarely spreads to the penis, but if it does, it will be found only at the base of the penis. It is often spread to the groin from fungal infection of the feet (tinea pedis).

Tinea cruris is usually associated with pruritus and is more common in postpubertal males. People at higher risk include those who have diabetes mellitus, are obese, recently visited a tropical climate, wear tight-fitting or wet clothes (including bathing suits) for extended periods, share clothing with others, or participate in sports.

Look For

Look for circular or annular, red, scaly plaques extending from the inguinal creases, down the medial thigh, and all around the pubic area and buttocks. The plaques usually have a sharply demarcated edge and a central clearing. Plaques are described as having an active border, meaning that the advancing edge of the plaque has prominent scale containing fungal hyphae. The central clearing of the elevated patches or plaques leads to the appearance of annular lesions and, thus, the description "ringworm" (a misnomer). The area affected may be moist and exudative in acute infections and dry in chronic infections.

Diagnostic Pearls

In fungal lesions that have been treated with topical steroids, the redness can be absent, and minimal scaling may be present while the lesion is loaded with fungi. If the scraping is negative in a lesion that has not been treated, the lesion is probably not fungal in etiology.

Differential Diagnosis & Pitfalls

Allergic contact dermatitis
Irritant contact dermatitis
Erythrasma
Familial benign pemphigus (Hailey-Hailey disease)
Folliculitis
Intertrigo
Cellulitis or erysipelas
Psoriasis (inverse psoriasis)
Granuloma annulare
Cutaneous candidiasis
Lichen simplex chronicus
Extramammary Paget's syndrome
Glucagonoma syndrome
Condyloma
Lymphogranuloma venereum
Granuloma inguinale
Bowen's disease

Best Tests

Scrape the scaly, active border with a scalpel blade or edge of a glass slide. Collect scale on a slide and coverslip. Direct a drop of 10% KOH (potassium hydroxide) to the edge of the coverslip, or put a drop of the KOH on the scales before covering with the coverslip. Wait for about 5 minutes, then examine with the microscope. Observe for branching or curving fungal hyphae, which cross the keratin cell borders.

Management Pearls

Treat all active areas of infection simultaneously to prevent reinfection of the groin from other body sites. Treat clinically affected areas and a 2 cm margin of healthy-appearing skin, and continue to treat for 1 week after clinical resolution. Also advise drying the inguinal folds completely after bathing. Explain to the patient that permanent cure is rare, but proper treatment results in excellent control that will, however, require periodic re-treatment.

Therapy

Limited, localized disease should be treated topically. Allylamines (eg, terbinafine, naftifine) and imidazoles (eg, clotrimazole) are the mainstays of therapy. Allylamines may require shorter courses, but imidazoles are less expensive.

Use topical antifungals for 1–6 weeks, based on clinical response:

Terbinafine 1% cream or spray – apply once to twice daily
Clotrimazole 1% cream – apply twice daily
Econazole 1% cream – apply once to twice daily
Oxiconazole 1% cream – apply twice daily
Ciclopirox 0.77% cream, gel, or lotion – apply twice daily
Ketoconazole 2% cream – apply once to twice daily
Miconazole 2% cream – apply twice daily
Naftifine 1% cream – apply once to twice daily
Butenafine 1% cream – apply once to twice daily

Topical corticosteroids by themselves or in combination with antifungals are generally not indicated and are absolutely contraindicated in immunosuppressed patients. Use of corticosteroid-antifungal combinations in cases of diagnostic uncertainty may lead to persistent fungal infections and is not recommended.

Extensive disease, particularly when other body parts are involved, may require weeks of oral antifungal agents:

Terbinafine 250 mg once a day for 2–4 weeks
Itraconazole 100–200 mg twice a day for 1 week
Fluconazole 150–300 mg once a week for 2–4 weeks
Griseofulvin ultramicrosize 5 mg/kg/day for 4–8 weeks (generally reserved for severe cases)

Systemic antifungals are contraindicated in patients with liver disease; monitoring of liver enzymes is generally recommended.

References

Gupta AK, Cooper EA. Update in antifungal therapy of dermatophytosis. Mycopathologia. 2008 Nov-Dec;166(5-6):353-67. PubMed Id: 18478357

Verma S, Heffernan MP. Superficial fungal infection: Dermatophytosis, Onychomycosis, Tinea Nigra, Piedra. In: Fitzpatrick TB, Wolff K, eds. Fitzpatrick's Dermatology in General Medicine. 7th ed. New York, NY: McGraw-Hill; 2008:1815.

Kyle AA, Dahl MV. Topical therapy for fungal infections. Am J Clin Dermatol. 2004;5(6):443-51. PubMed Id: 15663341

Gupta AK, Chaudhry M, Elewski B. Tinea corporis, tinea cruris, tinea nigra, and piedra. Dermatol Clin. 2003 Jul;21(3):395-400, v. PubMed Id: 12956194

Lebwohl M, Elewski B, Eisen D, Savin RC. Efficacy and safety of terbinafine 1% solution in the treatment of interdigital tinea pedis and tinea corporis or tinea cruris. Cutis. 2001 Mar;67(3):261-6. PubMed Id: 11270304

van Heerden JS, Vismer HF. Tinea corporis/cruris: new treatment options. Dermatology. 1997;194 Suppl 1:14-8. PubMed Id: 9154395

Drake LA, Dinehart SM, Farmer ER, Goltz RW, Graham GF, Hardinsky MK, Lewis CW, Pariser DM, Skouge JW, Webster SB, Whitaker DC, Butler B, Lowery BJ, Elewski BE, Elgart ML, Jacobs PH, Lesher JL, Scher RK. Guidelines of care for superficial mycotic infections of the skin: tinea corporis, tinea cruris, tinea faciei, tinea manuum, and tinea pedis. Guidelines/Outcomes Committee. American Academy of Dermatology. J Am Acad Dermatol. 1996 Feb;34(2 Pt 1):282-6. PubMed Id: 8642094

Associated Findings

Appearance
No Acute Distress

Body Location
Buttocks
Crural or Inguinal Fold
Leg
Suprapubic/Mons Pubis
Thigh

Distribution
Bilateral
Intertriginous
Widespread Male Genital

Lesion
Scale Fine
Scaly Plaque

Occupations
Military

Signs and Symptoms
No Fever (Afebrile, Apyrexial)
Obesity
Pruritus (Itching)

Temporal
Developed Acutely Over Days to Weeks
Developed Steadily Over Weeks to Months

Medical History
Diabetes Mellitus
Diabetes Mellitus Type I
Diabetes Mellitus Type II