Objective: Almost all of the small polypoid gallbladder cancers (less than 15 mm in diameter) are carcinoma-in-adenoma. On the other hand, the sonographic (US) features of large polypoid gallbladder cancers (large polypoid tumors), which grow intraluminally and are more than 20 mm in size, have not been clearified.
Methods: Among 162 patients with resection of gallbladder cancer, thirteen patients who had large polypoid tumors were evaluated. The US appearance was compared with the pathological features of the resected specimen. Survival was compared with that of patients who had early gallbladder cancer (defined as tumors with invasion limited to the muscle layer).
Results: The outer high echoic layer of the gallbladder was intact in all patients. All of the tumors were seen as solid low-echogenicity masses that were very similar in appearance to early gallbladder cancers. Distortion of the outer high echoic layer with sifting toward the tumor was observed in five patients. On pathological examination, the major part of each tumor was composed of proliferation of cancer cells in the mucosal layer, and even when the tumor invaded the subserosa, it only showed minimal invasion. The 5-year survival rate was 92 %, which was not significantly different (p=0.66) from that for early gallbladder cancer.
Conclusions: Large polypoid tumors have similar sonographic features to those of early cancers, except for traction on the outer high echoic layer in some patients. Even if the tumor invades the subserosa, long-term survival is similar to that of patients with early gallbladder cancer.