A 28-year-old man from Mumbai presents with a 6-month history of asymptomatic, hypopigmented patches over his chest and back. The lesions are non-pruritic and non-scaly to the naked eye. On examination, fine scale becomes apparent on gentle scratching. KOH mount of scale shows short, stubby hyphae and round yeast cells in clusters ('spaghetti and meatballs' appearance). Wood's lamp examination reveals coppery-orange or gold fluorescence. What is the most likely diagnosis?

Explanation

## Diagnosis: Pityriasis Versicolor ### Clinical Presentation The patient presents with the classic triad of pityriasis versicolor (PV): 1. **Hypopigmented or hyperpigmented patches** (depending on skin type and sun exposure) 2. **Fine scale** (subtle, revealed only on scratching) 3. **Non-pruritic, asymptomatic course** The lesions are typically distributed over the **chest, back, shoulders, and neck** — areas with high sebaceous gland density. ### Diagnostic Confirmation **Key Point:** The KOH mount finding of **'spaghetti and meatballs'** (short, stubby hyphae mixed with round yeast cells) is pathognomonic for Malassezia furfur, the causative organism of PV. **High-Yield:** Wood's lamp shows **coppery-orange, gold, or yellow-green fluorescence** due to porphyrins produced by the organism. This is a rapid bedside diagnostic tool. ### Organism & Pathophysiology | Feature | Detail | |---------|--------| | **Causative agent** | Malassezia furfur (lipophilic yeast) | | **Morphology** | Dimorphic: yeast and mycelial forms | | **Habitat** | Normal skin flora; lipid-dependent | | **Predisposing factors** | Warm, humid climate; oily skin; immunosuppression; genetic predisposition | | **Pathogenesis** | Produces dicarboxylic acids → inhibits tyrosinase → hypopigmentation | **Clinical Pearl:** PV is more common in tropical and subtropical regions like India, particularly in young adults (15–40 years). The condition is **not contagious** but tends to **recur** if not treated adequately. ### Treatment Overview **First-line options:** - Topical azoles (clotrimazole, miconazole) or terbinafine for localized disease - Selenium sulfide 2.5% lotion (apply for 10 minutes daily for 7 days) - Pyrithione zinc shampoo **Systemic therapy** (for extensive disease): - Fluconazole 150 mg weekly × 2–4 weeks - Itraconazole 200 mg daily × 5–7 days **Tip:** Hypopigmentation may persist for weeks after successful treatment due to slow repigmentation. Reassure the patient and consider sun exposure to hasten recovery.