Ultraviolet-induced Fluorescence Patterns in Psoriasis: Insights from a Large International Cohort Study

Psoriasis is a common skin disease displaying a broad spectrum of clinical presentations that can sometimes pose diagnostic challenges. UV-induced fluorescence dermatoscopy (UVFD) is a novel dermatoscopy mode useful as a complementary diagnostic method in inflammatory dermatoses. The understanding of red fluorescence in psoriasis, caused by protoporphyrin IX, in regard to clinical-morphological features, site-dependency, geographic variability, and bleaching with sun-exposure remains very limited.

The study objective was to explore fluorescence patterns in relation to demographic and geographic factors, disease subtype, lesion morphology, Psoriasis Area and Severity Index (PASI) score, seasonal variations, and bathing practices.

This study included 356 UVFD images from 111 psoriatic patients naive to the treatment from Central and Southern Europe and explored fluorescence patterns in relation to demographic and geographic factors, disease subtype, lesion morphology, Psoriasis Area and Severity Index (PASI) score, seasonal variations, and bathing practices. For the statistical analysis we have employed a series of Chi-squared tests for independence and independent samples t-tests.

Red fluorescence was predominantly observed in subtypes affecting sun-protected areas in patients with higher PASI scores, especially erythema and induration. Geographic and seasonal variability was observed, while age, sex, and bathing practices did not significantly affect fluorescence patterns.

The study confirms that red fluorescence in psoriatic lesions under UVFD is suppressed by sun exposure and correlates with disease severity.