Interobserver agreement among pathologists in the histopathological diagnosis and classification of colorectal polyps

OBJECTIVE: To assess interobserver agreement among pathologists in the diagnosis and classification of colorectal polyps. METHODS: This cross-sectional study was conducted at Afzalipour Educational and Medical Center from 2017 to 2018. Three experienced pathologists independently evaluated 253 colorectal polyp specimens, encompassing a spectrum of neoplastic and non-neoplastic lesions. Polyps were classified into six categories and dysplasia was graded. Interobserver agreement was assessed using weighted Cohen's kappa coefficient. RESULTS: The mean age of patients was 51.09 ± 20.11 years, with an average polyp size of 6.6 ± 0.6 mm. Most polyps (49.8%) were located in the colon, with 69.1% measuring 1-5 mm. Neoplastic polyps constituted 59.3% of the samples. Interobserver agreement for overall histopathological diagnosis was good (κ = 0.66). Agreement was very good for carcinoma in situ (κ = 0.87), good for adenomatous (κ = 0.78) and juvenile polyps (κ = 0.76), moderate for hyperplastic polyps (κ = 0.45), and poor for Inflammatory Polyps (κ = 0.16), solitary rectal ulcer (κ = 0.12), and sessile serrated polyps (κ = 0.14). Agreement on dysplasia grading was fair (κ = 0.32). CONCLUSION: While agreement was good for adenomatous polyps and carcinoma, considerable variability exists in diagnosing certain polyp types and grading dysplasia. These findings highlight the need for standardized criteria and additional training to improve consistency in colorectal polyp assessment, particularly for serrated lesions and dysplasia grading.