Follow-up study of gallbladder polyps diagnosed as benign with endoscopic ultrasonography

By EUS, we diagnosed 99 patients with benign gallbladder polyps between 1989 and 2004. We classified polyps morphologically into 3 groups based on surface structure, shape of the base, and internal echoes: group A, with flat or smooth surface structure, a thin stalk, and homogeneous echoes; group B, finely granular surface structure, and hyper-echoic echoes; and group C, granular surface structure, and coarse and scattered echoes. We looked for changes for over time in the 3 groups every 3 to 6 months. We calculated doubling time (DT) from initial observation for polyp size. Groups. A, B and C respectively consisted of 27, 28, and 99patients. Mean observation periods in groups A, B, and C were 3.4, 8.2, and 10.2 months respectively. In 3 group A patients, internal echoes changed from hyper-echoic and homogeneous to iso-echoic and heterogeneous. These polyps, showed rapid growth and were diagnosed pathologically as carcinoma in adenoma. The other 24 patients, who did not undergo surgery, did not show changes in internal echoes but 9 showed growth. Polyps showed growth in only 11 of 28 patients in group B. No patient in group B underwent surgery. In group C 12 of 99 patients underwent surgery, pathologic examinations disclosed cholesterol polyps. Twelve of the 87 patients, not undergoing surgery, showed growth of polyps and 4 showed an increase in number of polyps. DT in group A ranged from 10.3 to 408.8 days (mean, 198); in group B, 18.2 to 1587.2 days (mean, 789.3); and in group C 81.5 to 4102.9 days (mean, 1120.1). Based on DT, an appropriate observation period was considered to be 3 months for group A, 10 months for group B, and 12 months for group C. EUS is useful for diagnosis of gallbladder polyps. However, polyps with characteristics as in our group A should be followed up closely, that group B or C features can be followed up at longer interval.