Supplementary Material for: Postoperative Pyoderma Gangrenosum: Rare Infection Mimic and Diagnostic Challenge

Abstract Background: Pyoderma gangrenosum (PG) is a rare neutrophilic dermatosis that can occur in the postoperative period, often mimicking surgical site infections (SSIs). The clinical overlap between PG and SSIs—including erythema, wound dehiscence, and purulent discharge—makes timely diagnosis challenging. Case Presentation: A 61-year-old female with a history of ovarian cancer and metachronous liver metastasis underwent an open left hemihepatectomy. On the fifth postoperative day, she developed erythema, wound dehiscence, and necrosis unresponsive to broad-spectrum antibiotics. Wound cultures remained sterile. Dermatologic consultation and histopathology confirmed the diagnosis of PG, characterized by dense neutrophilic infiltration and pyogenic folliculitis. High-dose corticosteroid therapy led to marked clinical improvement within five days, with full wound healing achieved by discharge. Conclusion: Postoperative PG should be considered in non‑resolving postoperative wound complications with negative cultures and antibiotic failure. In this context, prior exposure to PARP inhibitors may be a biologically plausible co‑factor through immune modulation; however, a causal link remains unproven. Early dermatology consultation and biopsy are essential to avoid harmful debridement and expedite immunosuppression.