Tinea Cruris (Jock Itch)

Key Features

Essentials of Diagnosis

• Marked itching in intertriginous areas, usually sparing the scrotum

• Peripherally spreading, sharply demarcated, centrally clearing erythematous lesions

• May have associated tinea infection of feet or toenails

• Laboratory examination with microscope or culture confirms diagnosis

General Considerations

• Tinea cruris lesions are confined to the groin and gluteal cleft

• Intractable pruritus ani may occasionally be caused by a tinea infection

Clinical Findings

Symptoms and Signs

• Itching may be severe, or the rash may be asymptomatic

• Typical lesions are erythematous and sharply demarcated, with central clearing and active, spreading scaly peripheries

• Follicular pustules are sometimes encountered

• The area may be hyperpigmented on resolution

Differential Diagnosis

• Other lesions of the intertriginous area

  • Erythrasma: best diagnosed with Wood light—a brilliant coral-red fluorescence is seen

  • Candidiasis

    • Generally bright red and marked by satellite papules and pustules outside of the main border of the lesion

    • Candida typically involves the scrotum

  • Seborrheic dermatitis: also often involves the face, sternum, axillae, and genitalia (but not the crural folds)

  • Intertrigo

    • Tends to be less red, less scaly

    • Tends to be present in obese individuals in moist body folds with less extension onto the thigh

  • Psoriasis of body folds ("inverse psoriasis")

    • Inverse psoriasis is characterized by distinct plaques

    • Other areas of typical psoriatic involvement should be checked

    • The KOH examination will be negative

Diagnosis

Laboratory Tests

• Hyphae can be demonstrated microscopically in KOH preparations

• The organism may be cultured

Treatment

Local measures

• See preparations listed in Table 6–2

• Terbinafine cream is curative in over 80% of cases after once-daily use for 7 days

Systemic measures

• Itraconazole, 200 mg once daily orally, or terbinafine, 250 mg once daily orally, for 1 week, can be effective

• Griseofulvin ultramicrosize is reserved for severe cases; give 250–500 mg twice daily orally for 1–2 weeks

Outcome

Prevention

• Drying powder (eg, miconazole nitrate [Zeasorb-AF]) can be dusted into the involved area in patients with excessive perspiration or occlusion of skin due to obesity

Prognosis

• Usually responds promptly to treatment but often recurs

When to Refer

• If there is a question about the diagnosis, if recommended therapy is ineffective, or if specialized treatment is necessary

References