Epidemiology of Pyoderma Gangrenosum in Italy: Temporal Trends and Impact of the COVID-19 Pandemic

Introduction: Pyoderma gangrenosum (PG) is a rare, ulcerative neu- trophilic dermatosis that has shown fluctuating incidence over time. This study analyzes the epidemiology of PG in Italy from 2009 to 2024, with particular attention to trends in new diagnoses and the potential impact of the COVID-19 pandemic. Methods: Data were collected from four Italian centers (Pisa, Milan, Bologna, and Turin) and included total annual diagnoses, gender distribu- tion, and patient age. The analysis highlights temporal trends, comparing pre-pandemic (2009-2019), pandemic (2020-2022), and post-pandemic (2023-2024) periods. Results: Between 2009 and 2024, PG cases exhibited an overall increas- ing trend, particularly after 2013. In 2020, there was a noticeable decrease in PG diagnoses across all centers, reflecting the challenges posed by the COVID-19 pandemic. However, diagnoses were still reported (Pisa: 0 cases; Milan: 2 cases; Bologna: 2 cases; Turin: 1 case), indicating some level of continued healthcare access. Diagnoses increased further in 2021 (Pisa: 5 cases; Milan: 9 cases; Bologna: 5 cases; Turin: 4 cases), with a sharp rise observed in 2022 (total: 29 cases), surpassing pre-pandemic levels. Gender distribution remained consistent, with a predominance of female patients. The mean age of diagnosis varied slightly among centers but showed no significant shift across the study period. Discussion: PG diagnoses have increased significantly since 2021, possibly due to resumed post-pandemic activities or an actual rise in disease occurrence. The testing of vilobelimab (IFX-1), a complement C5a inhibitor, for both COVID-19 and PG suggests shared immunological pathways involving neutrophilic activity and complement system activa- tion. Connections between COVID-19 and PG exacerbation underscore the need to monitor individuals with neutrophilic dermatoses during and after COVID-19 infection or vaccination.