A rapidly progressing, painful ulcer at a surgical wound site

A woman in her early 30s was referred to a multidisciplinary care team (dermatology, hospital infection control, burns, microbiology, and wound care) with eight days of fever (≤42°C), redness, swelling, pain, and progressive ulceration of her caesarean section wound. Symptoms started within 24 hours of the procedure. The ulceration became rapidly extensive and pain increased, despite simple incision and drainage (on day 4) and a range of intravenous broad spectrum antibiotics and intravenous immunoglobulin.. Eight days after surgery, the ulceration measured 25 cm×15 cm and showed an irregular eminence and overhanging violaceous edge around the incision site (fig 1). Table 1 presents relevant investigation results on day 9 after the caesarean section.