Pyoderma gangrenosum — SCE Dermatology MCQ

Correct answer: E — Systemic immunosuppression and atraumatic wound care

The correct answer is E, systemic immunosuppression and atraumatic wound care. The clinical picture (rapidly enlarging, painful ulcer following minor trauma, violaceous undermined edge, negative culture, raised CRP without fever, and underlying ulcerative colitis) is classic for pyoderma gangrenosum (PG), a neutrophilic dermatosis strongly associated with inflammatory bowel disease. Diagnosis is clinical and by exclusion (of infection, vascular disease and malignancy), and PG shows pathergy, meaning any tissue trauma including surgery can dramatically worsen the ulcer. Management is therefore systemic anti-inflammatory or immunosuppressive therapy (corticosteroids first line, with ciclosporin, biologics or other agents for resistant disease) combined with gentle, non-adherent wound dressings that avoid mechanical trauma to the wound bed. Why the other options are wrong: D. Wide surgical debridement to healthy tissue: debridement and other trauma provoke pathergy in PG, typically causing rapid extension of the ulcer rather than healing. A. Compression therapy as sole treatment: compression is appropriate for venous ulcers with associated oedema but does not address the underlying neutrophilic inflammation of PG and will not halt progression used alone. B. Topical antifungal therapy with occlusion: there is no fungal infection here (culture negative), and occlusive antifungal dressings do not treat the immune-mediated pathology or the pain and expansion seen in PG. C. Repeated curettage and cautery: this is a mechanical intervention that, like debridement, risks triggering pathergy and worsening the ulcer; it is used for conditions like viral warts or solar keratoses, not PG. Key point: A violaceous, undermined, rapidly progressive ulcer in a patient with IBD, with negative cultures, points to pyoderma gangrenosum, where trauma (including surgery) worsens disease via pathergy, so treatment is systemic immunosuppression plus atraumatic wound care, not debridement.

Reference: George C, Deroide F, Rustin M. Pyoderma gangrenosum: a guide to diagnosis and management. Clinical Medicine (RCP) 2019;19(3):224-228. https://pmc.ncbi.nlm.nih.gov/articles/PMC6542232/