Tinea cruris

1. jock itch/tinea cruris is a common infection of the groin area in young men
2. caused by Trichophyton rubrum 
3. The dermatophytes responsible for tinea thrive in damp, warm, dark sites. 
4. It is transmitted by towels and other objects, particularly in locker rooms, saunas and communal showers
5. Differentials
   1. Simple intertrigo
   2. Skin disorders:
      1. psoriasis
      2. seborrhoeic dermatitis
      3. dermatitis/eczema
   3. Fungal:
      1. Candida
      2. tinea
   4. Erythrasma
   5. contact dermatitis

1. CLINICAL FEATURES
   1. Itchy rash
   2. More common in young males
   3. Strong association with tinea pedis (athlete’s foot)
   4. Usually acute onset
   5. More common in hot months—a summer disease
   6. More common in physically active people
   7. Related to chafing in groin (e.g. tight pants, and especially synthetic jock straps)
   8. Scaling, especially at margin
   9. Well-defined border
   10. The feet should be inspected for evidence of tinea pedis. 
   11. If left untreated, the rash may spread, especially to the inner upper thighs, while the scrotum is usually spared. 
   12. Spread to the buttocks indicates T. rubrum infection.

7. Complications:
   1. Maceration and secondary infection with bacteria or candida
   2. Secondary excoriation, lichenification, and pigmentation
   3. Tinea incognita due to use of topical steroids

8. DIAGNOSTIC AIDS
   1. Skin scrapings should be taken from the scaly area for preparation for microscopy 
   2. Wood’s light may help the diagnosis, particularly if erythrasma is suspected.

9. MANAGEMENT
   1. Fastidious drying of skinfolds.
   2. Apply topical terbinafine 1% cream or gel once or twice daily for 7–14 days or an imidazole topical preparation (e.g. miconazole or clotrimazole cream).
   3. Apply tolnaftate dusting powder bd when almost healed to prevent recurrence.
   4. If itch is severe, a mild topical hydrocortisone preparation (additional) can be used.
   5. For persistent or recurrent eruption, use oral terbinafine for 2–4 weeks or griseofulvin for 6–8 weeks.

2. Candida intertrigo

• Candida albicans superinfects a simple intertrigo and tends to affect patients with predisposing factors (e.g. broad-spectrum antibiotic therapy, diabetes, general debility, immune incompetence, obesity, immobility).

• CLINICAL FEATURES
  1. Erythematous, macerated rash
  2. Occurs in flexures, submammary area and other skinfolds
  3. Less well-defined margin than tinea 
  4. Associated satellite lesions and whitish discharge
  5. Yeast may be seen on microscopy

TREATMENT

1. Treat predisposing factors where possible.
2. Apply an imidazole preparation such as miconazole 2% or clotrimazole 1%, twice daily for 2 weeks.
3. Use short-term hydrocortisone cream for itch or inflammation (long-term aggravates the problem).