Ultrasonographic difficulties and pitfalls in diagnosing primary carcinoma of the gallbladder.

In order to more specifically define gallbladder carcinoma with real-time ultrasonography, a retrospective study was performed involving 29 sonographically false-negative and 22 sonographically false-positive cases of gallbladder carcinoma. Among the false negative cases, 18 (62.1%) were diagnosed as gallbladder stone only, 6 cases (20.7%) were incorrectly diagnosed as either acute or chronic cholecystitis, 2 cases (6.9%) were diagnosed as bile sludge, 2 cases (6.9%) were diagnosed as polyps, and 1 case (3.4%) was diagnosed as liver tumor. In false-positive cases, 8 (31.8%) were erroneously diagnosed as liver tumor. In false-positive cases, 7 (31.8%) were erroneously diagnosed as a mass projecting from the gallbladder wall but were pathologically proven to be polyps (4 cases) or bile sludge (3 cases); 8 cases (36.4%) were incorrectly diagnosed due to irregular thickening of the gallbladder wall but histology revealed them to be acute (3 cases) or chronic (5 cases) cholecystitis. Seven cases (31.8%) had a solid mass in porta hepatis, indicating gallbladder carcinoma; of these, 2 cases were lumps of bile sludge and 5 cases were acute cholecystitis with empyema. The differentiation of gallbladder carcinoma from cholecystitis (acute or chronic), polyps, and bile sludge is sometimes very difficult. With an understanding of the sonographic pitfalls and difficulties in the diagnosis of gallbladder carcinoma, a more specific diagnosis may be made.