Pyoderma Gangrenosum Across the Rheumatologic Spectrum: A Systematic Review and Meta-Analysis

Background/Aim Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis frequently associated with systemic inflammatory diseases, particularly inflammatory bowel disease and rheumatic disorders. Although rheumatoid arthritis (RA) is widely recognized as the most common rheumatic comorbidity, the prevalence of RA among patients with PG has not been systematically quantified. The aim of this artic was to systematically evaluate rheumatic diseases associated with PG and to estimate the pooled prevalence of rheumatoid arthritis through a meta-analysis of observational studies. Material and methods A systematic review was conducted according to the PRISMA 2020 statement. PubMed/MEDLINE, Embase, Web of Science, SciELO, and LILACS were searched from database inception through June 2026. Observational studies reporting rheumatic diseases in patients with PG were included, whereas case reports, reviews, and studies without extractable data were excluded. A random-effects meta-analysis of proportions was performed to estimate the pooled prevalence of RA. Results Seven observational studies comprising 529 patients with PG were included in the qualitative synthesis. Four studies involving 492 patients provided sufficient data for quantitative analysis. Rheumatoid arthritis was the most consistently reported rheumatic disease, whereas other inflammatory disorders—including seronegative arthritis, psoriatic arthritis, systemic lupus erythematosus, Behçet disease, systemic sclerosis, ANCA-associated vasculitis, and Takayasu arteritis—were identified less frequently and were reported inconsistently across studies. The pooled prevalence of RA was 11.9% (95% confidence interval [CI], 9.3%–15.1%). No statistical heterogeneity was detected (I² = 0%); however, this finding should be interpreted cautiously given the small number of studies included in the quantitative synthesis. Conclusions Rheumatoid arthritis is a frequent and consistent comorbidity in patients with PG, affecting approximately one in nine patients. Although additional rheumatic diseases have been described, current evidence remains insufficient for robust quantitative synthesis because of heterogeneous reporting. These findings support routine rheumatologic evaluation in patients with PG and reinforce the concept of PG as a systemic inflammatory disease with clinically relevant musculoskeletal involvement.