What is the most likely cause and recommended treatment for a fungal infection of the pubic‑groin area?

Fungal Infection Near Pubic Area: Diagnosis and Treatment

Most Likely Diagnosis

The most likely cause is tinea cruris ("jock itch"), a dermatophyte fungal infection of the groin area, which should be treated with topical antifungal therapy for 2 weeks. 1, 2

Differential Diagnosis

The pubic-groin area can harbor two distinct types of fungal infections that require different management:

Tinea Cruris (Jock Itch) - Most Common

• Caused by dermatophyte fungi (Trichophyton rubrum, T. mentagrophytes, Epidermophyton floccosum), not Candida species 1, 2
• Presents with erythematous, scaly, well-demarcated patches with raised borders extending from the groin folds onto the thighs 1, 3
• Does not typically involve the scrotum or vulvar mucosa (key distinguishing feature from candidiasis) 3

Cutaneous Candidiasis - Less Common in Groin

• Caused by Candida species (usually C. albicans) 4
• Affects intertriginous regions including groins with satellite lesions, maceration, and often involves adjacent skin folds 4
• More common in patients with diabetes, obesity, or immunosuppression 5

Diagnostic Confirmation

Before initiating treatment, confirm the diagnosis with:

• Potassium hydroxide (KOH) preparation of skin scrapings from the active border to visualize fungal hyphae (for dermatophytes) or yeast/pseudohyphae (for Candida) 1, 2, 4
• Culture is rarely required unless initial treatment fails or the diagnosis is uncertain 1
• Clinical appearance: tinea cruris shows well-demarcated borders with central clearing, while candidiasis shows beefy-red erythema with satellite pustules 3, 4

Treatment Algorithm

For Tinea Cruris (Dermatophyte Infection)

First-Line Topical Therapy:

• Terbinafine 1% cream applied once or twice daily for 2 weeks (RR 4.51 vs placebo for clinical cure, NNT 3) 2
  • Requires fewer applications and shorter duration than azoles 2
  • Continue for at least 1 week after clinical clearing 1

Alternative Topical Options:

• Naftifine 1% cream once daily for 2 weeks (RR 2.38 vs placebo for mycological cure, NNT 3) 2
• Clotrimazole 1% cream twice daily for 2 weeks (RR 2.87 vs placebo for mycological cure, NNT 2) 2
• Other azoles (miconazole, econazole, ketoconazole) twice daily for 2 weeks 1, 2

When Systemic Therapy Is Needed:

• Extensive infection covering large body surface area 1
• Resistance to initial topical therapy after 4 weeks 1
• Immunocompromised patients 5

For Cutaneous Candidiasis (If Confirmed)

• Topical azole antifungals (clotrimazole, miconazole, ketoconazole) applied twice daily for 2 weeks 4
• Keep the area dry and reduce moisture 3

Critical Pitfalls to Avoid

• Do not use combination antifungal/steroid creams as first-line therapy for tinea cruris, despite their higher short-term clinical cure rates, because they can cause skin atrophy and mask the infection's true extent 2
• Do not confuse tinea cruris with vulvovaginal candidiasis - the latter involves vaginal mucosa with discharge, pruritus, and normal pH ≤4.5, requiring different treatment 6, 7
• Do not treat without diagnostic confirmation when the clinical picture is atypical, as other conditions (psoriasis, eczema, erythrasma) can mimic fungal infections 1
• Avoid stopping treatment when symptoms improve - continue for at least 1 week after clinical clearing to prevent relapse 1

Adjunctive Measures

• Keep the groin area cool and dry by wearing loose-fitting cotton underwear and avoiding tight clothing 3
• Dry thoroughly after bathing, particularly in skin folds 3
• Treat concurrent tinea pedis (athlete's foot) if present, as it serves as a reservoir for reinfection 4
• Avoid sharing towels or clothing to prevent transmission 3

Follow-Up Recommendations

• Re-evaluate if symptoms persist after 2 weeks of appropriate topical therapy 1
• Consider culture and systemic therapy if no improvement after 4 weeks 1
• Recurrent infections warrant evaluation for predisposing factors (diabetes, immunosuppression, obesity) 5