The utility of biopsy in pyoderma gangrenosum: a retrospective cohort study

Abstract Background Pyoderma gangrenosum (PG) is a rare skin condition characterized by chronic, painful ulcerations. It is considered a diagnosis of exclusion, often resulting in diagnostic delay. Histological results in PG, even when biopsied despite a risk of pathergy, are nonspecific. Objectives To examine retrospectively the utility of biopsies in the diagnosis of 58 patients treated for PG. Methods Medical records were reviewed to compare biopsy results versus the efficacy of diagnostic rating systems (Delphi, Su, PARACELSUS). Results Among 58 patients, 26 (45%) underwent biopsies, with only 10 (38%) contributing to a PG diagnosis. As a single-centre and retrospective study, documentation style and sample size limit generalizability. Conclusions Given risk of pathergy, nonspecific histopathological findings and low sensitivity, in our opinion, based on this small sample size, biopsies have limited diagnostic value for PG.