Sonographic diagnosis of unsuspected gallbladder cancer: imaging findings in comparison with benign gallbladder conditions.

Abstract

Several sonographic findings were analyzed to determine their significance in distinguishing gallbladder cancer from benign conditions of the gallbladder. The analyzed findings were gallstone number and size; floating stones; displaced stones; wall thickening, irregularity, and echogenicity; mucosal plaque; intraluminal mass; gallbladder-replacing mass; invasive gallbladder mass; gallbladder mucosal discontinuity; hyperechoic gallbladder mucosa; and submucosal or transmural echolucency. Sonograms of 20 patients with unsuspected, pathologically proven gallbaldder cancer and 65 patients with benign gallbladder conditions (predominantly acute or chronic cholecystitis) were retrospectively assessed by two observers who were unaware of experimental conditions. Gallstone number and size were assessed, and the presence of floating stone (neither settling nor wall-adherent), displaced stone (lifted from the gallbladder wall by mass or focal wall thickening), wall irregularity, mucosal plaque, intracystic mass, and gallbladder-replacing or invasive mass was evaluated. The echogenicity pattern of the gallbladder wall was characterized, and its thickness was measured and classified as normal/mildly thickened (< 7 mm) or moderately/severely thickened (> or = 7 mm). In addition, the gallbladder wall was evaluated for discontinuous mucosal echo, hyperechoic mucosa, submucosal or mural echolucency, and pericholecystic fluid collection. Sonographic findings were compared by the Mann-Whitney test for nonparametric variables and by Student's t test for continuous variables. Solitary gallstone, displaced stone, intraluminal mass, gallbladder-replacing or invasive mass, and discontinuity of the mucosal echo were all statistically significantly more common in patients with gallbladder cancer (.001 < p < .05). Mucosal plaque and wall irregularity were nonspecific findings. Gallbladder wall thickening by itself was nonspecific, although associated echolayering, transmural or submucosal edema, or a distinctly specular mucosal lining favored benign etiologies. Several sonographic findings were significantly more common in patients with gallbladder cancer compared with patients with benign gallbladder conditions. Assessment of these signs may be helpful in distinguishing gallbladder cancer from benign conditions of the gallbladder.