Diagnostic ultrasound ( PDFDrive )

202 PART II Abdominal and Pelvic Sonography
examination as a thick-walled gallbladder with gallstones. Differentiation
from acute cholecystitis is made by the absence of
other signs, namely, gallbladder distention, Murphy sign, and
hyperemia in the wall. 93 Bouts of acute cholecystitis may complicate
chronic cholecystitis.
Xanthogranulomatous cholecystitis is a rare form of chronic
cholecystitis in which collections of lipid-laden macrophages
occur within grayish yellow nodules or streaks in the gallbladder
wall. In addition to gallstones, hypoechoic nodules or bands
within the thickened wall, representing the lipid-laden xanthogranulomatous
nodules, may suggest the diagnosis. 94
Porcelain Gallbladder
Calciication of the gallbladder wall is termed porcelain gallbladder.
Its cause is unknown, but it occurs in association with
gallstone disease and may represent a form of chronic cholecystitis.
his rare entity is seen in up to 0.8% of cholecystectomy specimens,
with a female predominance and most oten found in
the sixth decade of life. 95 Two large studies disputed a high
incidence of gallbladder carcinoma in porcelain gallbladder,
suggesting the coincidental occurrence of the two entities in up
to 7% of patients. 96,97 Nevertheless, prophylactic resection is
advised. 94
he degree and pattern of calciication determine the sonographic
appearance (Fig. 6.43). When the entire gallbladder wall
is thickly calciied, a hyperechoic semilunar line with dense
posterior acoustic shadowing is noted. Mild calciication appears
as an echogenic line with variable degrees of posterior acoustic
shadowing. he luminal contents may be visible. Interrupted
clumps of calcium appear as echogenic foci with posterior
shadowing. 76 Diferential diagnosis includes gallstones and
emphysematous cholecystitis. Because the calciications occur
in the wall of the gallbladder, the wall-echo-shadow complex is
absent (see “Gallstone Disease”).
Adenomyomatosis (Adenomatous
Hyperplasia)
Gallbladder adenomyomatosis is a benign condition caused by
exaggeration of the normal invaginations of the luminal epithelium
(Rokitansky-Aschof sinuses) with associated smooth muscle
proliferation (Fig. 6.44). he afected areas demonstrate thickening
of the gallbladder wall with internal cystic spaces, the key to the
radiologic diagnosis. he great majority of adenomyomatoses
are asymptomatic. 98
Adenomyomatosis may be focal or difuse. he most common
appearance on sonography is tiny, echogenic foci in the gallbladder
wall that create comet-tail artifacts, presumably caused by either
the cystic space itself or the internal debris (Fig. 6.45). Prominent
masslike focal areas of adenomyomatosis, called adenomyomas,
are the next most common manifestation. Careful evaluation of
the adenomyoma, sometimes requiring higher frequency or linear
probes, can show several features that are diagnostic of the entity
and allow for diferentiation from neoplasm. he most diagnostic
inding, although not the most common, is the presence of cystic
spaces. Echogenic foci with comet-tail or “twinkling” artifact on
Doppler examination are also typical. Focal adenomyomatosis is
most common in the gallbladder fundus, less oten narrowing
the midportion of the organ, called hourglass gallbladder
(Fig. 6.46).
Fundal adenomyomas are oten folded onto the body of the
gallbladder and can occasionally be mistaken for a pericholecystic
or even a hepatic mass. he entire gland wall may be involved,
causing collapse of the lumen. he absence of the cystic spaces,
echogenic foci, or twinkling artifact or the presence of internal
vascularity should prompt further investigation to diferentiate
from neoplasm. MRI or MRCP allows for improved speciicity,
with the presence of cystic spaces within the thickened wall
leading to the diagnosis. 99
A
B
FIG. 6.43 Porcelain Gallbladder. (A) Sonogram. (B) Corresponding CT scan. On ultrasound, this appearance could be mistaken for a stone
within the gallbladder lumen. There is, however, no gallbladder wall supericial to the echogenic focus.