Summary Background. Pyoderma gangrenosum (PG) is an uncommon condition, but can lead to the diagnosis of an underlying systemic disease. It can appear spontaneously or as a result of the pathergy phenomenon after trauma or surgery. Methods. We review three patients with postoperative PG (PPG) and the relevant literature. We also report an accurate method for microbial detection by 16S ribosomal (r)RNA sequencing. Results. A 47-year-old woman and two men aged 54 and 48 years, respectively, presented with sterile ulcerations after surgery. Associated conditions (Crohn’s disease and leukaemia) were present. Surgical wound infection was suspected and systemic empirical antibiotics were prescribed. After infection was excluded, PPG was diagnosed and corticosteroids were started. Discussion. PPG should be considered in the differential diagnosis of postsurgical wound complications. Recognition of this condition may prevent unnecessary administration of antimicrobial treatment and development of more extensive ulcerations. It may also be the clue for the diagnosis of an underlying systemic disease. We discuss the usefulness of 16S rRNA sequencing for microbial detection and identification in order to exclude a causative infection in patients who have previously received antibiotic treatment.
