Concurrent Hidradenitis Suppurativa and Pyoderma Gangrenosum in a Pediatric Cohort: A Retrospective Case Series

Hidradenitis suppurativa (HS) and pyoderma gangrenosum (PG) are chronic neutrophilic dermatoses characterized by dysregulated inflammation. Their coexistence in adults has been reported, but this has not been well documented in pediatric populations.

To characterize the overlap, clinical characteristics, and treatment options for pediatric patients with concurrent HS and PG.

We conducted a retrospective case series of pediatric patients ages 3 to 17 with clinical diagnoses of HS and PG at The Hospital for Sick Children between January 2015 and January 2022. Demographic, clinical, laboratory, genetic, and treatment data were extracted from electronic medical records and analyzed descriptively.

Seven of 122 pediatric HS patients (5.7%) had concurrent PG. HS onset preceded PG in all cases, with mean onset ages of 11.6 and 16.1 years, respectively. The cohort had a slight male predominance (57%) and high rates of comorbidities, including obesity (71.4%) and acne conglobata (42.9%). Elevated erythrocyte sedimentation rate (ESR) (mean 56.9 mm/hour) was a significant predictor of HS severity (P = .027). Three patients had autoinflammatory gene variants, and 57.1% met criteria for PASH or PAPA syndrome. Cytokine profiling revealed elevated IL-1β and IL-6 in select cases. Three of 4 patients who underwent incision and drainage for HS developed PG at the surgical sites.

Pediatric patients with HS-PG may represent a distinct, severe inflammatory subset. Further investigation is needed to define risk factors, inflammatory biomarkers, and optimal treatment strategies in this rare overlap population.