Evaluation of the concordance between clinical diagnosis and biopsy in cutaneous vasculitis

Cutaneous vasculitis poses a diagnostic challenge due to its variable presentations and overlap with other dermatologic conditions. Although biopsy is essential for confirmation, the concordance between clinical suspicion and histopathological findings remains uncertain. This study aimed to assess the agreement between the diagnostic impression of specialists and biopsy-confirmed vasculitis in adults. This retrospective study analyzed 200 patients who underwent skin biopsy at a tertiary care hospital in Colombia between February 2017 and December 2024. Patients were classified according to clinical suspicion of vasculitis by dermatologists or rheumatologists. Researchers collected and analyzed clinical features and histopathological findings. Concordance between clinical and histopathological findings was assessed using Cohen's kappa coefficient. Of the 200 patients, 107 had clinical suspicion of vasculitis. Mean age was 46.9 years, with 55.5 % females. Vasculitis was confirmed histologically in 80 (74.7 %) of those with clinical suspicion, and in 19 (20.4 %) of those with alternative clinical diagnoses. Small vessel vasculitis predominated (87.8 %), followed by medium-sized and mixed vessel involvement. Concordance analysis revealed moderate agreement between clinical suspicion and histopathological confirmation for the group of specialists (κ= 0.54; 95 % CI: 0.40 to 0.67). No significant association was found between specialist experience and diagnostic agreement in vasculitis. Inflammatory biomarkers were similar among patients with or without confirmed vasculitis. This study highlights the low diagnostic agreement between clinical and biopsy- confirmed vasculitis, emphasizing and highlighting the need for biopsy collection as a diagnostic tool. Paraclinical tests do not appear to be decisive for performing skin biopsy.