The association between erythema nodosum and pyoderma gangrenosum and pediatric inflammatory bowel disease

Objectives: The objectives of this study is to estimate rates and identify factors associated with erythema nodosum (EN) and pyoderma gangrenosum (PG) in pediatric patients with inflammatory bowel disease (IBD). Methods: This cohort study examined longitudinal visits of patients aged ≤ 21 years from the ImproveCareNow (ICN) registry. We evaluated the association of factors at the patient-level (demographics and IBD diagnosis age) and visit-level (IBD severity scores, markers and phenotypes, comorbidities, and treatment) with the presence of EN and PG, using longitudinal logistic regression models adjusted for time and within-patient clustering. Results: A total of 285,913 visits from 32,497 patients aged ≤ 21 years from the ICN registry were analyzed. The occurrence of EN was 1.57% (95% confidence interval [95% CI]: 1.43%–1.71%) and the occurrence of PG was 0.90% (95% CI: 0.80%–1.00%). Co-occurrence of EN and PG was reported in 0.30% (95% CI: 0.25%–0.37%) patients. Both EN and PG were associated (p < 0.0001) with worse intestinal disease, lower remission, higher inflammatory markers, and extraintestinal manifestations (EIMs) arthritis and uveitis. Conclusions: EN and PG were associated with increased disease severity and other noncutaneous EIMs (arthritis and uveitis). A small subset of patients had developed both EN and PG.