Pyoderma Gangrenosum: Association of Ulcer Size With Clinical Characteristics and Healing Outcomes

Pyoderma gangrenosum (PG) is an ulcerative inflammatory dermatosis that is poorly characterised from a diagnostic and therapeutic perspective. We evaluated the clinical characteristics and healing outcomes in patients with PG according to ulcer size.

We reviewed the medical records of patients with PG presenting to a tertiary hospital in Melbourne, Australia, from 20 December 2011 to 11 June 2024. We collected data on demographics, clinical characteristics, and classified cases into small (< 64 cm²) or large ulcers (≥ 64 cm² or any tendon or muscle on view) according to the size of the largest ulcer during the treatment course. Healing outcomes assessed included rates of initial healing, healing time, recurrence rate, healing after recurrence, level of systemic treatment required, and mortality.

81 cases of PG were identified, including 38 (46.9%) small and 43 (53.1%) large ulcers. Large ulcers were associated with a history of multiple ulcers, peripheral vascular disease, and higher rates of advanced treatment (biologic or intravenous immunoglobulin therapy). After adjusting for age, sex, and peripheral vascular disease, large ulcers remained independently associated with lower rates of initial healing, higher rates of recurrence, lower rates of healing after recurrence, and longer healing times (all p < 0.05). Ulcer size was not associated with age, sex, ulcer location, tissue pathergy, inflammatory bowel disease, haematological malignancy, inflammatory arthritis, or diabetes mellitus.

PG is a highly morbid condition that is slow to heal and frequently recurs. Ulcer size is an important predictor of healing outcomes. It is thus a meaningful way of stratifying patients and may provide useful prognostic information regarding the expected disease course.