Unequal burden: Inguinal sentinel lymph node biopsy and the disproportionate risk of infection in melanoma.

Abstract

To evaluate surgical site-specific infection rates after sentinel lymph node biopsies (SLNB) for melanoma. This single-centre retrospective analysis of prospectively collected data included 422 patients who underwent SLNB between January 2020 and January 2025. Negative post-operative outcomes within 31 days were recorded: infection, seroma, wound dehiscence, haematoma, lymphedema and other complications. Clinical variables included: demographics, SLNB site and result, comorbidity, prophylactic antibiotic use and American Joint Committee on Cancer stage. Multivariable logistic regression was used to identify predictors of infection. This study adheres to the STROBE guidelines (Supplementary Appendix). Across the 422 patients in the cohort (mean age 59.1 years, range 6-89 years), infection accounted for 55 cases (13%). Rates varied markedly by site: inguinal 23.9%, axilla 7.8%, knee 29.4% and head/neck 3.0%. All infections were managed with antibiotics, and none required re‑operation. Multivariable analysis revealed that inguinal site (OR 5.01, 95% CI 2.50-10.04, p < 0.001) and male gender (OR 2.57, 95% CI 1.30-5.09, p = 0.007) independently predicted postoperative infection. Age and comorbidity were not associated with increased risk in our cohort. Within this UK cohort, the SLNB anatomical site emerged as the strongest driver of postoperative infection, with inguinal procedures carrying the greatest increase in risk. Male patients were also at a higher risk of infection. These findings highlight the value of targeted prevention strategies and close postoperative surveillance for high-risk groups.