Diagnostic accuracy of ultraviolet-induced fluorescence dermoscopy in non-neoplastic dermatoses (general dermatology): A multicentric retrospective comparative study

Background: Preliminary data support the possible use of ultraviolet-induced fluorescence (UVF) dermoscopy in general dermatology, yet no accuracy analysis has been performed so far. Objective: To evaluate diagnostic accuracy of UVF dermoscopy in clinically similar non-neoplastic conditions as compared to polarized light-based dermoscopy. Methods: Patients with dermatoses potentially showing UV-induced findings were considered; cases were grouped according to clinical patterns and controls were also included. Standardized evaluation of dermoscopic pictures of the target lesion along with comparative and accuracy analysis were performed for polarized and UVF dermoscopic findings. Results: A total of 208 patients were included [31 foot intertrigo (7 due to Pseudomonas, 13 due to Corynebacterium and 11 due to dermatophytes); 57 intertrigo of major creases (18 inverse psoriasis, 13 erythrasma, 15 tinea infections and 11 candidiasis); 16 acne (papulopustular) and 13 Malassezia folliculitis; 46 papulosquamous dermatoses (14 guttate psoriasis, 11 lichen planus, 12 pityriasis rosea and 9 pityriasis lichenoide chronica); and 45 hypopigmented macular dermatoses of the trunk (9 progressive macular hypomelanosis, 9 idiopatic guttate hypomelanosis, 13 vitiligo and 14 achromic pityriasis versicolor)]. Significant (p < 0.01) UVF was seen in several conditions: green in Pseudomonas foot intertrigo; red in Corynebacterium foot intertrigo, inverse and guttate psoriasis (arranged around dermal papillae in the former), progressive macular hypomelanosis (folliculocentric distribution) and erythrasma (showing polygonal or structureless appearance); blue fluorescent concretions along hair shaft in erythrasma; light green in achromic pityriasis versicolor and tinea of major creases; and blue follicular in Malassezia folliculitis. Additionally, both acne and achromic pityriasis versicolor were also associated with interruption of uniform follicular red fluorescence. Notably, polarized and UVF dermoscopy were related to the most accurate feature in nine and eight analysed dermatoses, respectively. Conclusion: UVF dermoscopy improves recognition of non-neoplastic dermatoses, yet it should be considered complimentary to polarized light-based dermoscopy to increase diagnostic performance.