Abstract: 【Abstract】 Objective To analyze clinical characteristics, treatment, and outcomes of 36 patients with pyoderma gangrenosum, and to compare and evaluate the applicability and consistency between the PARACELSUS score and Delphi criteria. Methods From January 2000 to January 2022, clinical data were collected from 36 patients who were diagnosed with pyoderma gangrenosum in the Hospital of Dermatology, Chinese Academy of Medical Sciences. The PARACELSUS score and Delphi criteria were applied to their diagnosis, and the kappa test was used to evaluate the consistency between the two diagnostic criteria. Results Among the 36 patients, 6 （16.67%） had definite precipitating factors before the onset, and 31 （86.11%） exhibited lesions with different degrees of pain. Ulcerative lesions predominatd in 31 （86.11%） patients, which mostly involved the lower extremities, while 16 （44.44%） presented with multiple lesions all over the body. Four （11.11%） patients were complicated by inflammatory bowel disease, and 3 （8.33%） with inflammatory arthritis. Glucocorticoids, Tripterygium wilfordii, and cyclosporin were the main systemic treatment options, and tumor necrosis factor-α antagonist was used in 8 （22.22%） patients. Twenty-two （64.71%） and 17 （50.00%） patients were diagnosed with pyoderma gangrenosum using the PARACELSUS score and Delphi criteria, respectively. The kappa test showed moderate agreement between the two diagnostic criteria （kappa value = 0.47, 95% CI: 0.19 - 0.76, P = 0.004）. Conclusions Classic ulcerative subtype was the major subtype in the patients with pyoderma gangrenosum, who were usually complicated by inflammatory bowel disease and inflammatory arthritis. Glucocorticoids and immunosuppressants were the main therapeutic drugs. The PARACELSUS score and Delphi criteria focus on different aspects of pyoderma gangrenosum, and the PARACELSUS score is recommended in the context of absence of typical histopathological manifestations.

Key words: Pyoderma gangrenosum, Diagnosis, PARACELSUS score, Delphi criteria, Agreement