Phantom gallbladder. A variant of the rim sign.

Nonvisualization of the gallbladder is the primary finding in cholescintigraphy for acute cholecystitis. Recent investigators have described a useful secondary finding of increased pericholecystic hepatic activity (PCHA). A case of acute cholecystitis is presented in which the PCHA was round in configuration and appeared in the first 5 minutes of the study. This may be a source of diagnostic error if it is interpreted as visualization of the normal gallbladder. Appearance of the PCHA has not been previously described before 30 minutes. This case of early appearance raises the possibility that hyperemia may play a role as the cause in some forms of the PCHA. The phantom gallbladder was correctly identified as PCHA by observing the peak of activity of the PCHA occurring before the appearance of intrahepatic biliary radicals.