Early carcinoma of the gallbladder: macroscopic features and US findings. To facilitate early detection of carcinoma of the gallbladder, a comparative study of macroscopic forms and ultrasonographic (US) features of stage I (TNM staging system) gallbladder cancer was carried out retrospectively in 71 cases of such carcinomas that were resected surgically. Macroscopic forms of the lesions were classified into four types: pedunculated (eight cases), sessile (15 cases), superficial raised (25 cases), and flat (23 cases). Among 71 cases, only 20 were diagnosed preoperatively by means of US. US patterns of the lesions were also classified into four types: fungating mass, lumen filling, smooth raised, and thickening of mucosa. US features corresponded well to the macroscopic forms. No flat lesion was identified preoperatively. For early detection of carcinoma of the gallbladder, it seemed essential to pay careful attention to mild mucosal change, as more than 50% of early cancers did not show apparently protruding lesions. 