Ultrasonographic examination disclosed diffuse wall thickening and coment-tail artifact in two cases of adenomyomatosis
(ADM) of the gallbladder, and laparoscopic cholecystectomy was performed. In case 1, found in a 41-year-old man, the
excised gallbladder showed general thickening of the wall and multiple intramural gallstones in the dilated Rokitansky-Aschoff
sinuses (RAS). These stones were mainly cholesterol-crystal stones like those described by Yunotani: square, transparent,
crystalloid stones with glittering glasslike surfaces; and a smaller number of mixed stones consisting of cholesterol and pigment.
Water-bath scan of the removed stones showed only the cholesterol-crystal stones to have the typical comet-tail artifact. Infrared
spectrometry of one of the cholesterol-crystal stones showed cholesterol content to exceed 98% , In case 2, found in a 36-year-old man, the excised gallbladder also showed general thickening of the wall, and the dilated RAS contained numerous
black intramural stones and several cholesterol-crystal stones. Water-bath scan of the gallbladder showed comet-tail artifacts like
those seen in the extracorporal ultrasonogram. Water-bath scan of the removed stones showed only the cholesterol-crystal stones
to produce comet-tail artifacts. These results suggest that cholesterol-crystal stones, characteristic of intramural gallstones, may
be the origin of the comet-tail artifact seen in ADM of the gallbladder.