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Yellow Plaque Disease (Pityriasis Versicolor)

Overview

Pityriasis versicolor, also known as yellow plaque disease, is a common superficial fungal infection of the skin caused by the yeast Malassezia (formerly Pityrosporum) . The organism normally lives on the skin of healthy adults, but under certain conditions it multiplies excessively, altering the color and texture of the skin. The infection typically produces round or oval patches that may be lighter (pink, yellow, or white) or darker (brown, tan) than the surrounding skin.

While anyone can develop the condition, it is most prevalent among:

• Teenagers and young adults (15‑30 years), especially during late summer and early autumn.
• People living in hot, humid climates.
• Individuals who sweat heavily or wear tight, non‑breathable clothing.

Epidemiological data suggest a worldwide prevalence of approximately 20‑50 % in tropical regions and 5‑10 % in temperate zones (Mayo Clinic; WHO). The condition is usually benign and not contagious, but it can be cosmetically distressing and may recur frequently.

Symptoms

The appearance of pityriasis versicolor can vary widely, but the most common manifestations include:

• Discolored patches – round, oval or irregular macules ranging from 1 cm to several centimeters. Color may be yellow, pink, white, brown, or tan.
• Fine scaling – a subtle, sandpaper‑like surface that becomes more evident when the skin is stretched (the “scratch test”).
• Itching or mild burning – usually absent, but some patients report mild pruritus, especially in hot weather.
• Texture change – patches may feel slightly thicker or feel “flaky.”
• Location – most often on the chest, back, shoulders, neck, and upper arms; less commonly on the abdomen, groin, and rarely on the face.
• Post‑inflammatory hyper‑ or hypo‑pigmentation – after the infection clears, the area may remain lighter or darker for months.

Causes and Risk Factors

What causes pityriasis versicolor?

The disease results from an overgrowth of Malassezia yeast, which is lipophilic (fat‑loving) and thrives on the oily sebaceous secretions of the skin. When the yeast proliferates, it produces acids that interfere with melanin synthesis, leading to the characteristic color changes.

Key risk factors

• Warm, humid environments – moisture encourages yeast growth.
• Excessive sweating – athletes, manual laborers, or people who wear non‑breathable fabrics.
• Oily skin or excessive sebum production – common in adolescents and during hormonal changes.
• Immunosuppression – HIV infection, chemotherapy, organ transplant recipients, or corticosteroid therapy.
• Genetic predisposition – family members may share a tendency for overcolonization.
• Age – sebaceous gland activity peaks in the teenage years.
• Recent antibiotic or broad‑spectrum antifungal use – can disturb normal skin flora.

Diagnosis

Because the lesions can mimic other skin disorders (e.g., eczema, tinea corporis, vitiligo), a careful evaluation is essential.

Clinical examination

• Visual inspection of the shape, color, and distribution of patches.
• “Scratch test” – gently scraping the lesion with a glass slide; if fine scales appear, it supports the diagnosis.

Diagnostic tests

1. Wood’s lamp examination – the lesions often fluoresce a yellow‑green color under ultraviolet light, although fluorescence is not always present.
2. KOH (potassium hydroxide) preparation – a scraping of the scale is placed on a slide with KOH; under microscopy, you can see the classic “spaghetti‑and‑meatball” pattern of hyphae and spores.
3. Culture – rarely needed, but a Sabouraud agar culture can grow Malassezia if the diagnosis is uncertain.
4. Dermatoscopy – may reveal fine scaling and pigmentation patterns supportive of the condition.

In most primary‑care settings, a combination of visual assessment and KOH microscopy is sufficient (CDC, 2023).

Treatment Options

Treatment aims to eradicate the yeast, restore normal skin coloration, and prevent recurrence. Because the fungus resides in the stratum corneum, topical agents are often effective; systemic therapy is reserved for extensive or refractory disease.

Topical antifungals

Medication	Formulation	Typical Duration
Ketoconazole	2 % cream, shampoo	2–4 weeks
Clotrimazole	1 % cream	2–4 weeks
Selenium sulfide	2.5 % shampoo	2–3 washes weekly for 2 weeks
Terbinafine	1 % cream	2–4 weeks
Ciclopirox	1 % cream	2–4 weeks

Application instructions:

• Clean the affected area with mild soap and water, pat dry.
• Apply a thin layer of cream or spread shampoo‑treated lather over the lesions; leave on for 5‑10 minutes before rinsing (for shampoos).
• Continue treatment for the full prescribed period, even if lesions appear cleared, to reduce recurrence.

Systemic (oral) antifungals

Reserved for widespread disease, recurrence after multiple topical courses, or involvement of areas difficult to treat (e.g., scalp). Common regimens (Cleveland Clinic):

• Fluconazole 200 mg once weekly for 2–4 weeks.
• Itraconazole 200 mg twice daily for 5–7 days (pulse therapy) or 100 mg daily for 4 weeks.
• Terbinafine 250 mg once daily for 2–4 weeks.

Baseline liver function tests are recommended before initiating oral therapy, especially in patients with liver disease or who take other hepatotoxic drugs.

Adjunctive & lifestyle measures

• Use an anti‑fungal shampoo (selenium sulfide or ketoconazole) 2‑3 times weekly as a maintenance regimen for 2‑3 months after clearance.
• Wear loose, breathable clothing (cotton, linen) to reduce moisture.
• Avoid excessive oily skin products; choose non‑comedogenic moisturizers.
• Practice good hygiene: shower promptly after sweating and dry skin thoroughly.

Living with Yellow Plaque Disease (pityriasis versicolor)

Even after successful treatment, the condition may recur. Here are practical strategies for daily management:

• Sun protection – UV exposure can accentuate the contrast between affected and normal skin. Use SPF 30+ sunscreen daily.
• Regular skin checks – Examine your chest, back, and shoulders weekly for new patches, especially after summer vacations.
• Antifungal maintenance routine – Incorporate a medicated shampoo into your routine (e.g., twice weekly) during humid months.
• Weight control and diet – While diet does not cause the infection, maintaining a healthy weight can reduce excessive sebum production.
• Stress management – Stress can alter immune function and increase sweating; regular exercise, meditation, or yoga may help.

Prevention

Because Malassezia is a normal skin inhabitant, prevention focuses on limiting overgrowth:

1. Keep skin dry – towel off promptly after bathing, shower after workouts, and use talc‑free powders in skin folds.
2. Choose appropriate clothing – synthetic fabrics that trap sweat (e.g., polyester) should be avoided; opt for moisture‑wicking athletic gear when needed.
3. Limit oily skin products – heavy creams, oils, or greasy sunscreens can feed the yeast.
4. Routine antifungal shampoo – especially in high‑risk seasons (summer, rainy seasons) or after travel to tropical areas.
5. Avoid prolonged use of broad‑spectrum antibiotics without medical indication, as they disrupt normal flora.

Complications

Although pityriasis versicolor is generally benign, untreated or recurrent disease can lead to:

• Persistent pigment changes – hypo‑ or hyper‑pigmentation may remain for months, causing cosmetic concern.
• Secondary bacterial infection – scratching or macerated skin can become colonized with bacteria such as Staphylococcus aureus.
• Psychosocial impact – visible lesions, especially on the torso or neck, can affect self‑esteem and lead to anxiety or depression.
• Rare extensive disease – in immunocompromised patients, the infection can become widespread and may require prolonged systemic therapy.

When to Seek Emergency Care

For routine flare‑ups, schedule an appointment with a dermatologist or primary‑care provider rather than using emergency services.

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Sources: Mayo Clinic. Pityriasis Versicolor. https://www.mayoclinic.org; CDC. Fungal Skin Infections. https://www.cdc.gov; WHO. Global Burden of Skin Diseases. 2022 report; Cleveland Clinic. Pityriasis Versicolor Treatment Guidelines; NIH National Library of Medicine, 2023.

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