Fungal Skin Infections

Patients typically describe a gradual onset of symptoms, including itching, scaling, or patches that enlarge over time. Recurrence is common.

General Risk Factors:

• A history of sweating, hot/humid climate, or the use of occlusive clothing.

• Exposure in communal areas (gyms, showers) or sharing equipment/towels.

Specific Types:

• Tinea pedis (Athlete’s foot): Itching between the toes (interdigital) or dry scaling over the soles ("moccasin-type"). Associated with sweaty feet and tight, occlusive footwear.

• Tinea cruris (Jock itch): Itchy, spreading rash in the groin folds, notably sparing the scrotum. Worse with heat and moisture.

• Tinea corporis (Ringworm): Expanding circular or ring-like patches with a raised border. Possible contact with pets or contaminated surfaces.

• Tinea capitis: Common in children. Symptoms include hair breakage, scaling, and tender areas, sometimes with painful swelling (kerion).

• Pityriasis Versicolor: The patient mainly notices colour change: recurrent patches that are either lighter (hypopigmented) or darker (hyperpigmented) on the chest, neck, or upper back. Usually not intensely itchy and worsens with sweating or oily skin.

Crucial Note for Darker Skin Tones:
Fungal infections often present primarily with pigment change rather than redness. Patients are more likely to report "discolouration," "light patches," or "dark patches" instead of a typical rash. The hyperpigmented margins of tinea or the striking hypopigmentation of Pityriasis Versicolor are often the chief complaint.

Diagnosis relies on visual pattern, scale, and border definition.

Tinea (Dermatophyte Infections):
Typically annular (ring-shaped) plaques with a leading active edge (the periphery) and scale at the border. There may be central clearing.

Tinea pedis:
Interdigital maceration (soft, white skin) and fissuring, or diffuse dry, fine scaling across the soles and side of the feet ("moccasin pattern").

Tinea cruris:
Red-brown or hyperpigmented patches in the groin folds with a sharply demarcated, advancing, scaly border.

Tinea capitis:
Patchy hair loss, fine scaling, and often "black dot" alopecia (broken hair shafts at the surface). A Kerion presents as a painful, boggy, swollen area.

Onychomycosis (Nails): Thick, crumbly, yellow/brown nails with subungual debris.

Pityriasis Versicolor:

• Multiple round/oval patches on the trunk or neck with a fine, powdery scale (scale can be "evoked" by scraping the lesion).

• Patches are highly variable in colour: hypopigmented, hyperpigmented, or salmon-coloured.

Key Considerations in Darker Skin Tones:

• Erythema is minimal or subtle; rely on the texture, scale, border, and reported itch/warmth.

• Tinea corporis lesions may appear purely darkened or hyperpigmented rather than red.

• Pityriasis versicolor can present with striking hypopigmentation that may be mistaken for vitiligo.

• Untreated Tinea capitis, especially Kerion, carries a high risk of permanent scarring alopecia. Post-inflammatory Hyperpigmentation (PIH) after treatment is common and long-lasting.

Treatment choice depends on the site of infection and depth.

1. Tinea (Dermatophyte Infections):

• Topical Antifungals (First-line for most body/feet/groin infections): Creams such as Terbinafine, Clotrimazole, or Ketoconazole. Apply 1–2 times daily for 2–4 weeks, continuing for at least one week after the rash clears.

  • Adjunctive Measures: Keep the skin dry and avoid occlusion. Treat household contacts for Tinea capitis.

• Oral Antifungals (Required for Scalp and Nails):

  • Required for: Tinea capitis, Onychomycosis, or extensive/refractory body/groin infections. Options include Terbinafine (first-line), Itraconazole, or Fluconazole.

  • Tinea Capitis: Always requires oral therapy plus an antifungal shampoo (Ketoconazole or Selenium Sulfide).

2. Pityriasis Versicolor:

• Topical Therapy (First-line): Selenium Sulfide or Ketoconazole shampoo/cream. The shampoo is often applied and left on for 5–10 minutes daily for one week, then weekly for maintenance.

• Oral Antifungals: Reserved for extensive or recurrent cases (e.g., Fluconazole single weekly doses).

Specific Guidance for Darker Skin Tones:

• Pigment Change: Explain that the pigmentation change (hypo- or hyperpigmentation) will take weeks to months to resolve after the fungus is completely cleared. This is critical for patient adherence and reassurance.

• PIH Management: Once the infection is gone, counsel on strict sun protection and consider topical agents like Azelaic acid, Vitamin C, or topical retinoids to expedite PIH resolution.

• Avoid Unnecessary Steroids: Never use topical steroids alone for tinea, as this leads to tinea incognito and worsens inflammation and subsequent pigmentation/scarring.

Skinsight – Common Complaints: Fungal Skin Infections: https://skinsight.com/health-topics/common-complaints-fungal-skin-infections/

DermNet NZ – Introduction to Fungal Infections: https://dermnetnz.org/topics/introduction-to-fungal-infections