The frequency and distribution of underlying systemic illnesses among individuals with pyoderma gangrenosum are not well understood. For a review, researchers compiled current information on the incidence of concomitant systemic disorders in pyoderma gangrenosum patients. A comprehensive review and meta-analysis of observational studies in MEDLINE, EMBASE, and Scopus (1823–2017) was conducted. A modified Newcastle–Ottawa Scale was used to evaluate the evidence’s quality. A meta-analysis was conducted to determine pooled prevalence rates with 95% confidence intervals using random-effects models.

The quantitative synthesis included 21 eligible studies with a total of 2,611 pyoderma gangrenosum patients. The total random-effects pooled prevalence of related systemic illnesses was 56.8% (95% CI: 45.5–67.4). Inflammatory bowel disease (17.6%; 95% CI: 13.0–22.7) was the most common underlying disease, followed by arthritis (12.8%; 95% CI: 9.2–16.9), hematological malignancies (8.9%; 95% CI: 6.5–11.6), and solid malignancies (7.4%; 95% CI: 5.8–9.1). The pathergy phenomenon was responsible for the start of pyoderma gangrenosum in 16.3% (95% CI 7.7–27.1) of patients.

A significant underlying illness was present in more than half of individuals with pyoderma gangrenosum. The most often related disorders were inflammatory bowel disease and arthritis. The pooled prevalence of arthritis and hematological malignancies was lower in comparison to the documented literature, but the pooled prevalence of solid malignancies was greater. Because most of the comparisons had a significant level of variability, the results are required to be evaluated with care.