Trend in the Diagnosis of Pyoderma Gangrenosum in Italy: A Multicenter Study

Introduction: Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis characterized by painful, rapidly progressive ulcerations, often associated with systemic inflammatory diseases. Despite advancements in diagnostic criteria, PG remains a diagnostic challenge, and recent increases in reported cases may reflect improved recognition rather than true incidence. This study evaluates epidemiological trends in PG diagnosis in Italy (2013-2024) across four dermatology centers (Bologna, Milano, Pisa, Torino) to determine whether increased number of diagnoses are due to refined diagnostic methodologies or external immunological factors. Methods: A cross-sectional analysis was conducted using anonymized data from four major dermatology centers in Italy. Data analysis deployed one-way ANOVA and Poisson regression models to assess temporal trends in PG diagnoses. Significance was set at α = 0.05. Results: Between 2013 and 2024, 213 PG cases were diagnosed across four Italian referral centers, with a female predominance (126 vs. 87). Diagnostic rates showed marked annual variability, including a 150% rise in 2015, a 68.8% drop in 2020, and a 360% rebound in 2021. Diagnoses more than doubled after 2018 (68 vs. 145; p < 0.05). Trends varied by center: Bologna (+0.25/year, p = 0.003) and Milano (+0.09/year, p = 0.03) showed significant increases; Pisa and Torino did not. Overall, the rise in diagnoses post-2018 aligns with the broader adoption of standardized diagnostic criteria. Conclusion: The increase in PG diagnoses recorded since 2018 is more plausibly explained by improved clinical recognition and widespread adoption of structured diagnostic frameworks than by a true rise in incidence. Regional variability and limitations of retrospective data caution against firm epidemiological conclusions. Prospective multicenter studies and standardized registries are needed to validate diagnostic tools, reduce misclassification, and clarify the true burden of PG.