More Than an Abscess: Vancomycin-Associated Resolution of Suspected Pyoderma Gangrenosum in Ulcerative Colitis

ABSTRACT A 46-year-old man with a 5-year history of ulcerative colitis presented with a rapidly progressive ulcer on the left ankle, presumed to be a methicillin-resistant Staphylococcus aureus abscess. Despite multiple courses of antibiotics and surgical drainage, the lesion did not improve; imaging and cultures remained negative for infection. Empiric intravenous vancomycin was given, after which the patient reported improvement in pain and erythema, although no pathogen was identified. Considering an active inflammatory bowel disease flare, lesion characteristics, sterile cultures, and mild pathergy, pyoderma gangrenosum (PG) was considered retrospectively. Although histopathology was not obtained, the clinical context strongly favored PG. This case underscores the diagnostic challenge and potential harm of misidentifying PG as infection.