Detectability on Plain CT Is an Effective Discriminator between Carcinoma and Benign Disorder for a Polyp >10 mm in the Gallbladder

An appropriate diagnosis is required to avoid unnecessary surgery for gallbladder cholesterol polyps (GChPs) and to appropriately treat pedunculated gallbladder carcinomas (GCs). Generally, polyps >10 mm are regarded as surgical candidates. We retrospectively evaluated plain and contrast-enhanced (CE) computed tomography (CT) findings and histopathological features of 11 early GCs and 10 GChPs sized 10–30 mm to differentiate between GC and GChP >10 mm and determine their histopathological background. Patient characteristics, including polyp size, did not significantly differ between groups. All GCs and GChPs were detected on CE-CT; GCs were detected more often than GChPs on plain CT (73% vs. 9%; p < 0.01). Sensitivity, specificity, positive and negative predictive values, and diagnostic accuracy for GCs were 73%, 90%, 89%, 75%, and 81%, respectively. On multivariate analysis, lesion detectability on plain CT was independently associated with GCs (odds ratio, 27.1; p = 0.044). Histopathologically, GChPs consisted of adipose tissue. Although larger vessel areas in GCs than in GChPs was not significant (52,737 μm(2) vs. 31,906 μm(2); p = 0.51), cell densities were significantly greater in GCs (0.015/μm(2) vs. 0.0080/μm(2); p < 0.01). Among GPs larger than 10 mm, plain CT could contribute to differentiating GCs from GChPs.