The Vinyl Adhesive Tape Technique With Methylene Blue for Diagnosis of Superficial Fungal Skin Infections

The Vinyl adhesive tape (VAT) technique with methylene blue (MTB) may be useful as an adjunctive microscopic method for diagnosis of superficial fungal skin infections. A cross-sectional study was conducted between 2022 and 2025 on adults with dermatophytosis, pityriasis versicolor, and cutaneous candidiasis confirmed by skin scraping with potassium hydroxide (KOH). VAT technique with MTB staining was performed at the same lesion. Data on clinical characteristics, hyphal index, and time to microscopic identification were recorded. The primary objective was the positivity rate of VAT technique with MTB in patients with superficial fungal skin infections confirmed by skin scraping and direct microscopy with KOH. Secondary objectives included identifying factors associated with positive results and comparing time to microscopic identification. Among 208 participants (mean [SD] age, 50.87 [19.36] years; 44% female), the overall positivity rate of VAT technique with MTB was 89.4% (186/208), with positivity rates of 83.3% (105/126) for dermatophytosis, 100% (41/41) for pityriasis versicolor, and 97.6% (40/41) for cutaneous candidiasis. In dermatophytosis, factors significantly associated with positive MTB results included onset of presentation equal or less than a week (adjusted OR 5.26, p = 0.023) and high hyphal index (adjusted OR 8.24, p = 0.002). For dermatophytosis, KOH microscopy yielded a shorter time to identification, whereas for pityriasis versicolor, the VAT technique with MTB was faster. Among KOH-confirmed cases, the VAT technique with MTB showed the highest positivity rate in pityriasis versicolor, followed by cutaneous candidiasis, whereas the positivity rate was lower in dermatophytosis.