Tinea Versicolor (Pityriasis Versicolor)
The most likely diagnosis is tinea versicolor (pityriasis versicolor), a superficial fungal infection caused by Malassezia species that characteristically presents as hypopigmented, reticulated, non-pruritic macules on the trunk and should be treated with topical ketoconazole 2% cream applied once daily for two weeks. 1, 2
Clinical Diagnosis
Tinea versicolor characteristically presents as scaly hypopigmented or hyperpigmented macules/patches primarily located on the upper trunk, neck, and upper arms—exactly matching this patient's distribution on abdomen and flank. 2
The non-pruritic nature is typical, as tinea versicolor is generally asymptomatic or minimally symptomatic. 3
The reticulated or hypopigmented appearance is pathognomonic for the hypopigmented variant (pityriasis versicolor alba), which occurs when fungal metabolites inhibit melanin synthesis. 4
Diagnosis is usually made clinically based on characteristic features without requiring laboratory confirmation. 2
If diagnostic uncertainty exists, potassium hydroxide (KOH) preparation reveals numerous short, stubby hyphae intermixed with clusters of spores ("spaghetti and meatballs" appearance). 2
First-Line Treatment
Topical antifungal therapy is the treatment of choice due to better safety profile, fewer adverse events, fewer drug interactions, and lower cost compared to systemic treatment. 2, 5
Apply ketoconazole 2% cream once daily to the affected area and immediate surrounding skin for two weeks to reduce recurrence risk. 1
Alternative topical options include zinc pyrithione shampoo, selenium sulfide, or terbinafine cream. 5, 6
Clinical improvement may be seen fairly soon after treatment begins, but the full two-week course is essential to prevent recurrence. 1
When to Consider Oral Therapy
Oral antifungal therapy should be reserved for specific situations: 2, 5
- Extensive disease covering large body surface areas
- Frequent recurrences despite topical therapy
- Disease refractory to adequate topical treatment
- Patient preference when compliance with topical therapy is poor
If oral therapy is indicated, use either itraconazole or fluconazole—oral ketoconazole should no longer be prescribed due to hepatotoxicity risk, and oral terbinafine is ineffective for tinea versicolor. 5
Critical Management Pitfalls
The hypopigmentation may persist for weeks to months after successful fungal eradication, as repigmentation requires time for melanocyte recovery and new melanin synthesis. 4
Patients must understand that clearing the infection does not immediately restore normal pigmentation—this prevents premature discontinuation of therapy or unnecessary retreatment. 4
Recurrence rates are high (up to 60% within one year) because Malassezia species are part of normal skin flora. 2, 6
Long-term intermittent prophylactic therapy should be considered for patients with frequent recurrences, such as monthly application of topical antifungals or periodic oral therapy. 5, 6
Differential Considerations to Exclude
While tinea versicolor is the clear diagnosis here, briefly consider:
Vitiligo presents with complete depigmentation (not hypopigmentation) and lacks the fine scale characteristic of tinea versicolor. 3
Post-inflammatory hypopigmentation requires a history of preceding inflammatory dermatosis. 3
Pityriasis alba occurs primarily on the face in children and has less distinct borders. 3
The non-pruritic nature and trunk distribution exclude inflammatory conditions like eczema or psoriasis. 2