Abstract: 【Abstract】 Objective To evaluate the value of modified calcofluor white fluorescent staining in the histopathological diagnosis of subcutaneous mycosis, in order to provide a new method for histopathological diagnosis of subcutaneous mycosis. Methods A total of 21 lesional skin tissues were collected from patients with subcutaneous mycosis in the Affiliated Hospital of Chengde Medical University between 1987 and 2017, and embedded in paraffin. Then, each paraffin-embedded tissue section was cut into 4 4-μm-thick serial sections, and subjected to modified calcofluor white fluorescent staining, hematoxylin and eosin （HE） staining, periodic acid Schiff （PAS） staining and Gomori methenamine silver nitrate （GMS） staining respectively. Positive rates and staining outcomes were compared among the above staining methods. Statistical analysis was carried out with SPSS 19.0 software by using chi-square test for comparing the positive rates among the above 4 staining methods. Results Of 21 patients with fungal infections, 14 （66.67%） were positive for modified calcofluor white fluorescent staining, 5 （23.80%） for HE staining, 6 （28.57%） for PAS staining, and 11 （52.38%） for GMS staining. The positive rate by modified calcofluor white fluorescent staining was significantly higher than that by HE staining and PAS staining （χ2 = 6.718, 5.200, respectively, both P < 0.05）, while no significant difference was observed between the modified calcofluor white fluorescent staining and GMS staining （χ2 = 0.693, P = 0.530）. Conclusion The modified calcofluor white fluorescent staining is an accurate method for detecting fungi, and has a certain application value in the histopathological diagnosis of subcutaneous mycosis.

Key words: Sporotrichosis, Blastomycosis, Candidiasis, Mucormycosis, Fluorescent staining