Interobserver Agreement in Histopathologic Diagnosis of Skin Lesions

Background: The concept of obtaining a second opinion is very popular in anatomical pathology, and multiple studies have shown its cost-effective benefits. This study aimed to determine the diagnostic discrepancy rate in skin biopsies in general pathology practice between first and second pathologists. Materials and Methods: A retrospective study was conducted on 760 consecutive patients who underwent skin biopsies and subsequent pathologic review over a one-year period. Based on the initial pathologist’s diagnosis, histopathological findings were primarily categorized as neoplastic or non-neoplastic. Neoplastic lesions were further divided into benign or malignant. A second pathologist reviewed all slides after codifying and without knowing the original diagnosis. Finally, the diagnoses provided by both pathologists were compared. Results: According to a primary pathologist, 243 cases (31.97%) were non-neoplastic and 517 (68.02%) were neoplastic. Of the 517 neoplastic lesions, 218 cases (42.16%) were benign and 299 (58.83%) were malignant. The major discrepancies were observed in 1.23%, 5.5%, and 1.01% of non-neoplastic, benign neoplastic, and malignant neoplastic groups, respectively. Kappa coefficient was 0.908 for non-neoplastic, 0.857 for benign, and 0.878 for malignant lesions. Conclusion: There was a high level of interobserver concordance in the histopathologic diagnosis of skin lesions in our study. We concluded that routine re-evaluation of all skin biopsies by a second pathologist may not be generally recommended except for cases needing aggressive therapeutic interventions to improve patient outcomes and quality of life.