Maximum polyp diameter and broad-based morphology predict neoplastic gallbladder polypoid lesions in the 10-15 mm gray zone: A retrospective study.

Objectives

To investigate the predictive value of preoperative conventional ultrasound features for identifying neoplastic lesions in patients with 10-15mm polypoid lesions of the gallbladder (PLG) who undergo laparoscopic cholecystectomy (LC) and received pathologic confirmation, to identify independent risk factors, and to assess their utility for preoperative risk stratification in surgical candidates.

Methods

This retrospective study included 144 patients with PLG measuring 10-15 mm who underwent LC between January 1, 2020, and January 1, 2026. Cases were classified into non-neoplastic and neoplastic groups based on postoperative pathology. Clinical characteristics and preoperative ultrasound features (including maximum polyp diameter, solitary lesions, broad-based morphology, echo homogeneity, surface lobulation, blood flow signals, gallbladder wall thickening, coexisting gallstones, bile mud and gallbladder adenomyomatosis signs) were compared between the groups. Univariate logistic regression was performed to identify candidate risk factors, and a multivariate logistic regression model was constructed considering the sample size and number of outcome events. The discriminative performance of individual indicators and the combined model was evaluated using receiver operating characteristic (ROC) curve analysis. Additionally, bootstrap resampling was used for internal validation of the model to assess its discrimination ability, calibration accuracy, and overfitting risk.

Results

Of the 144 patients, 124 (86.11%) had non-neoplastic lesions and 20 (13.89%) had neoplastic lesions. Significant between-group differences were observed in maximum polyp diameter, solitary lesions, broad-based morphology and gallbladder wall thickening (all P < 0.05). Multivariate logistic regression identified maximum polyp diameter (per 1 mm increase) (OR = 1.492, 95% CI: 1.016-2.191, P = 0.041) and broad-based morphology (OR = 34.630, 95% CI: 9.582-125.158, P < 0.001) as independent risk factors. The combined prediction model developed from these two factors achieved an apparent AUC of 0.918 (95% CI: 0.855-0.981, P < 0.001), and the bootstrap-corrected AUC was 0.916. Changes in the calibration slope and Brier score after correction were relatively small. In the surgical pathology cohort of this study, the optimal cutoff value of the combined model was 0.067, yielding 90.0% sensitivity and 83.1% specificity.

Conclusion

Among patients with 10-15 mm polyps who underwent LC and received pathologic confirmation, maximum polyp diameter and broad-based morphology were independent risk factors associated with neoplastic lesions. The combined model based on these two factors can be used as an exploratory auxiliary risk assessment tool for surgical candidates. A cutoff of 12.5 mm can be used as a exploratory value for the surgical pathology cohort in this study. However, these results and the model-predicted probability cutoff value cannot be directly extrapolated to all patients with 10-15 mm PLG. The model's external validity requires further validation.