What is a fungal rash?

Fungal Rash: Clinical Features and Management

Fungal rashes are cutaneous infections characterized by erythematous, pruritic lesions with various morphologies depending on the causative organism, requiring prompt identification and appropriate antifungal therapy to prevent complications and dissemination.

Clinical Presentation of Common Fungal Rashes

Candida Infections

• Present as superficial mucosal and cutaneous infections in up to 80% of high-risk patients 1
• Appear as single or multiple nodular skin lesions, discrete pink to red papules (0.5-1.0 cm) typically on trunk and extremities 1
• Can manifest as intertrigo, vaginitis, balanitis, perleche, and paronychia 1
• May become painful and hemorrhagic in thrombocytopenic patients 1

Dermatophyte Infections

• Common worldwide at all ages in both sexes 2
• Include tinea capitis (scalp), tinea cruris (groin), tinea pedis (feet), tinea corporis (body), tinea manuum (hands), and tinea barbae (beard area) 2
• Typically present with scaling, erythema, and sometimes central clearing with raised borders

Aspergillus Infections

• Cutaneous infections are unusual but may occur at IV catheter insertion sites or nail beds 1
• Begin as erythematous papules that progress to pustules with central ulceration 3
• Can produce painful skin nodules that rapidly become necrotic, resembling pyoderma gangrenosum lesions due to angioinvasion 1

Other Invasive Fungal Infections

• Rhizopus and Mucor species cause erythematous, nodular, and tender skin lesions 1
• Fusarium infections present as multiple erythematous macules with central pallor that quickly evolve to papules and necrotic nodules 1
• Trichosporon beigelii causes multiple erythematous macules to maculopapular lesions 1

Diagnosis

Direct Examination

• Wet mount preparation with saline and 10% potassium hydroxide to demonstrate yeast or hyphae 1
• Wood's lamp examination for certain fungal infections 3

Laboratory Testing

• Skin scrapings for microscopic examination and fungal culture 2
• Tissue biopsy with histopathological examination using fungal stains (Grocott methenamine silver) for invasive infections 1
• Serum fungal antigen tests (1,3-β-D-glucan or galactomannan) may have low sensitivity, particularly in patients receiving antifungal agents 1

Treatment Approach

Superficial Candida Infections

• Effectively treated with improved skin care and topical antifungal agent or short-course systemic azole (e.g., fluconazole) 1
• For vaginal candidiasis:
  • Uncomplicated cases: Single 150-mg dose of fluconazole 1
  • Complicated cases: Topical therapy administered intravaginally daily for ~7 days or multiple doses of fluconazole (150 mg every 72h for 3 doses) 1
  • Recurrent cases: 10-14 days of induction therapy with topical or oral azole, followed by fluconazole 150 mg once weekly for 6 months 1

Dermatophyte Infections

• Topical therapy is effective for limited disease 4
  • Azole drugs (miconazole, clotrimazole, ketoconazole) - fungistatic
  • Allylamines and benzylamines (terbinafine, naftifine, butenafine) - fungicidal, often preferred with shorter treatment times 4
• Oral therapy for extensive disease or hair/nail involvement:
  • Terbinafine, itraconazole, or fluconazole 5

Invasive Fungal Infections

• Recovery of fungi from aspiration or biopsy of skin or deep soft tissues warrants aggressive systemic antifungal therapy 1
• Treatment options based on organism:
  • Aspergillus: Voriconazole 1
  • Fusarium: High-dose IV voriconazole or posaconazole 1
  • Mucor/Rhizopus: Surgical treatment should be considered alongside antifungal therapy 1

Special Considerations

Immunocompromised Patients

• Skin lesions may represent early site of infection dissemination 1
• Fungal skin infections warrant immediate evaluation and aggressive treatment due to risk of dissemination 3
• Profoundly neutropenic patients with persistent fever who are systemically ill despite empirical antibiotic therapy may benefit from empirical antifungal treatment 1

Prevention

• Good personal hygiene is an important adjunct to antifungal therapy 2
• For recurrent infections, maintenance therapy may be required 1

Treatment Pitfalls and Caveats

• Patients often stop treatments when the skin appears healed, usually after about a week of treatment, leading to recurrence 4
• Yeast infections respond less well to allylamine drugs; azole drugs are often preferred 4
• Nail infections are difficult to cure with topical therapies due to poor penetration through the nail plate 4
• Fluconazole-resistant yeast (C. krusei and C. glabrata) are increasingly common due to widespread use of azole prophylaxis 1
• For C. glabrata infections, topical boric acid (600 mg daily for 14 days) may be successful when azoles fail 1