Evaluating diagnostic utility of PAS stained skin scrape cytology smear in clinically suspected superficial cutaneous mycoses: A simple yet unpracticed technique

BACKGROUND AND OBJECTIVES: For fungal dermatitis, a wet Potassium Hydroxide (KOH) preparation of the skin scrapings forms the routine practice for diagnosis. This study was carried out to determine the diagnostic accuracy and to evaluate the value-added information of PAS-stained scrape cytology smear in evaluating the presence of fungal elements. METHODS: This prospective study was carried out on the patients clinically diagnosed with superficial cutaneous mycoses. For each patient, a wet KOH preparation and one PAS-stained skin scrape cytology (SSC) smear was prepared. RESULTS: Out of the 52 suspected cases of superficial cutaneous mycoses, 50 showed fungal elements on either or both the techniques. The presentation was Tinea cruris together with Tinea corporis in 21 cases (42%), isolated tinea cruris in 19 cases (38%), tinea corporis in 8 cases (16%), and tinea corporis with tinea manuum and onychomycosis in 2 cases (4%). KOH preparation was positive in 45 out of 50 cases (90%) and SSC was positive in 49 out of 50 cases (98%). The sensitivity, specificity, positive predictive value, and negative predictive value for PAS-stained SSC smear was 98%, 100%, 100%, and 66% and that for KOH preparation was 90%, 100%, 100%, and 28%, respectively. Fungal elements quantity was graded on SSC smear as 1+(5), 2+(19), 3+(19), 4+(6), and in one case, it was negative. CONCLUSION: Incorporation of the PAS-stained SSC smear for fungal dermatitis ensures more efficient and confident diagnosis and the slides are available for archivable studies.