Clinical course and prognostic disparities of pyoderma gangrenosum based on underlying disease: A long-term comparative study in 124 patients

Background and objectives: Pyoderma gangrenosum (PG) is associated with inflammatory bowel disease (IBD), autoimmune and connective tissue diseases, and hematologic malignancies. The impact of these underlying diseases on the clinical course and outcomes of PG remains poorly understood. This study investigates the influence of systemic disease associations on the progression, treatment response, and prognosis of PG. Patients and methods: This study followed a cohort of 124 patients diagnosed with PG at a multidisciplinary referral institution between 2007 and 2024. Patients were stratified into four groups: IBD-associated PG (n = 52), autoimmune and connective tissue disease-associated PG (n = 24), hematologic malignancy-associated PG (n = 15), and idiopathic PG (n = 33). Outcomes, including remission and relapse rates, were analyzed using Kaplan-Meier survival curves and Cox proportional hazards models. Results: IBD-associated PG had the most favorable outcomes, with 75% of patients achieving remission at 12 months (M12) (Hazard Ratio [HR]: 2.56; 95% Confidence Interval [95%CI]: 1.49–4.35). Autoimmune and connective tissue disease-associated PG was the most treatment-refractory, with only 8.3% achieving remission at M12 (HR: 0.21; 95% CI: 0.10–0.50). Relapse occurred in 26.1% of patients, with no significant difference across the groups (p = 0.8). Bullous PG, predominantly linked to hematologic malignancies, exhibited accelerated healing but also a high rate of malignant transformations near PG onset. Conclusions: IBD-associated PG followed a more favorable clinical course compared to autoimmune and connective tissue diseases or hematologic conditions, highlighting the importance of tailored treatment approaches based on underlying disease associations.