DOI:10.2214/AJR.05.1284
AJR 2007; 189:W36-W38
© American Roentgen Ray Society
Adenomyomatosis of the Gallbladder: Another Cause for a "Hot" Gallbladder on 18F-FDG PET
Pierre D. Maldjian1,
Nasrin Ghesani1,
Shahida Ahmed2 and
Yiyan Liu1
1 Department of Radiology, UMDNJ-New Jersey Medical School, University Hospital,
150 Bergen St., UH C-320, Newark, NJ 07103-2406.
2 Pathology Service, Department of Veterans Affairs, New Jersey Health Care
System, East Orange, NJ.
Received July 25, 2005;
accepted after revision September 18, 2005.
Address correspondence to P. D. Maldjian
(maldjipd{at}umdnj.edu).
WEB
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Keywords: adenomyomatosis of the gallbladder • FDG PET • gallbladder carcinoma • nuclear medicine • oncologic imaging • PET/CT
Introduction
Studies of small numbers of patients have shown that 18F-FDG PET is useful
in differentiating benign from malignant lesions within the gallbladder
[1,
2]. However, a limitation of
FDG PET is that inflammatory conditions with increased glucose metabolism
cannot be distinguished from neoplasms because those conditions also show
increased uptake of the agent.
We present a patient with increased activity within the fundus of the
gallbladder on an FDG PET scan obtained for staging of colon carcinoma.
Pathologic examination of the gallbladder showed focal adenomyomatosis with no
evidence of malignancy. Adenomyomatosis of the gallbladder and the resulting
chronic inflammation can lead to false-positive FDG PET findings.
Case Report
An 80-year-old man with no significant medical history underwent screening
colonoscopy that revealed a 2-cm sessile polyp of the sigmoid colon. Biopsy
was positive for moderately differentiated adenocarcinoma.
A staging CT scan showed thickening of the wall of the gallbladder fundus
(Fig. 1A). An FDG PET/CT scan
was also obtained and showed increased activity in the sigmoid tumor and in
the fundus of the gallbladder (Figs.
1B and
1C). The standardized uptake
value (SUV) measured 4.7 in the region of increased activity in the
gallbladder. Because an SUV of greater than 2.5 is generally considered
suspicious for active neoplasm, the possibility of metastatic disease to the
gallbladder or a primary gallbladder neoplasm could not be excluded on the
basis of these results. Both the sigmoid lesion and the gallbladder were
surgically resected.
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Fig. 1A —80-year-old man who underwent CT and FDG PET/CT for staging
of sigmoid carcinoma. Axial CT scan after administration of IV contrast
material shows thickening of gallbladder fundus (arrow).
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Fig. 1C —80-year-old man who underwent CT and FDG PET/CT for staging
of sigmoid carcinoma. PET/CT fusion image confirms that activity localizes to
gallbladder fundus (arrow). Activity in renal collecting systems is
normal.
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At surgery, the gallbladder had an indurated area within the fundus.
Pathologic examination revealed gallbladder diverticulosis with
Rokitansky-Aschoff sinuses; muscular hypertrophy; and chronic inflammation
that was consistent with adenomyomatosis, which produces chronic acalculous
cholecystitis (Fig. 1D). There
was no evidence of malignant involvement.
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Fig. 1D —80-year-old man who underwent CT and FDG PET/CT for staging
of sigmoid carcinoma. Photomicrograph of pathologic specimen shows localized
invaginations of branching glands (Rokitansky-Aschoff sinuses) into wall of
gallbladder (arrows) accompanied by smooth-muscle hyperplasia, which
is consistent with adenomyomatosis. (H and E and trichrome stain)
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Discussion
Adenomyomatosis of the gallbladder is defined as epithelial proliferation
and hypertrophy of the muscularis with outpouchings of the mucosa into or
through the thickened muscular layer. These changes result in formation of the
characteristic Rokitansky-Aschoff sinuses. Adenomyomatosis of the gallbladder
is relatively common with a reported incidence of 2.8–5.0%
[3].
Based on the extent and location of disease, three forms of adenomyomatosis
of the gallbladder have been described: diffuse, segmental, and localized. The
diffuse form involves the entire gallbladder. The segmental type involves the
proximal, middle, or distal third of the gallbladder in a circular fashion.
The localized form is the most common type and involves only the fundus
[4]. This form can present as a
mass or as thickening of the fundus, as seen in our patient.
Distinguishing adenomyomatosis of the gallbladder from gallbladder
carcinoma is important because both can present with thickening of the
gallbladder wall or a focal mass. Identification of the manifestations of the
Rokitansky-Aschoff sinuses is the key to diagnosing adenomyomatosis of the
gallbladder on the basis of imaging studies.
The sonographic features of adenomyomatosis of the gallbladder are diffuse
or segmental gallbladder wall thickening with intramural diverticula seen as
anechoic spaces or as echogenic foci that may have acoustic shadows or
reverberation artifacts. The appearance of the Rokitansky-Aschoff sinuses on
sonography depends on their contents: Intramural diverticula containing bile
appear anechoic, whereas diverticula containing sludge, stones, or papillary
projections appear echogenic with associated acoustic shadowing or
reverberation artifact. The frondlike mucosal projections within
diverticula—with their multiple interfaces of widely different acoustic
impedances—are likely the cause of the reverberation or comet-tail
artifacts [4].
On MRI, the Rokitansky-Aschoff sinuses are seen as small cystic structures
in the thickened gallbladder wall best depicted on T2-weighted imaging
sequences [5]. On CT,
adenomyomatosis of the gallbladder presents as thickening of or as a mass in
the gallbladder wall. Occasionally, cystic spaces in the gallbladder wall may
be shown on CT, but the ability of CT to delineate the Rokitansky-Aschoff
sinuses is limited because of insufficient spatial and contrast resolution
[3].
FDG PET can also be helpful in characterizing lesions of the gallbladder.
Studies of small numbers of patients have shown that FDG PET is useful in
differentiating benign gallbladder lesions from gallbladder carcinoma. In
their study of 16 patients with gallbladder lesions, eight of whom had
gallbladder carcinoma, Koh et al.
[1] found that FDG PET had a
sensitivity of 75% (6/8) and specificity of 88% (7/8). There were two
false-negative cases. One was attributed to the small size of the tumor, 1.3
cm. In the second case, the patient had diabetes mellitus. FDG PET has a
decreased sensitivity for tumor detection in diabetic patients because the
elevated blood sugar level in diabetic patients competes with the agent for
uptake in tumor cells. The false-positive case was xanthogranulomatous
cholecystitis. This false-positive finding was attributed to FDG uptake by
active inflammatory cells. In this series, there were two cases of
adenomyomatosis of the gallbladder that did not show increased activity on FDG
PET.
Rodriguez-Fernandez et al.
[2] reported the results of FDG
PET in a case series of 16 patients with clinical symptoms suggestive of
biliary colic or chronic cholecystitis and with inconclusive sonography or CT
findings for gallbladder cancer. The aim of the study was to see whether FDG
PET could be used to differentiate cholecystitis from gallbladder carcinoma in
cases in which other imaging techniques were indeterminate. Increased
radiotracer activity within the gallbladder with an SUV of greater than 2.5
was considered positive for neoplasm. In this study, FDG PET showed a
sensitivity of 80% (4/5) and a specificity of 82% (9/11). There was only one
false-negative result in a patient with mucinous adenocarcinoma. There were
two false-positive results. One patient had tuberculoid granulomatosis of the
gallbladder. Interestingly, the second false-positive result was due to
adenomyomatosis of the gallbladder, although the images from that case were
not included in the article. Because all of the patients in the study were
symptomatic, we might assume that there was a significant amount of
inflammatory reaction in that second false-positive case.
The abnormal FDG accumulation in the case we present is limited to the
gallbladder fundus, which is the most common location for the focal form of
adenomyomatosis of the gallbladder; FDG accumulation at this location may help
in differentiating this entity from uptake of FDG secondary to acute
cholecystitis. In acute cholecystitis, the increased activity has been
described as involving the entire gallbladder wall with a ringlike appearance
[6]. Rimlike FDG uptake in the
gallbladder wall secondary to cholestasis from common bile duct obstruction
has also been described, although the cause for the increased metabolic
activity in that case was not clear
[7].
Although neoplasms of the gallbladder often show increased activity on FDG
PET, benign inflammatory or infectious lesions can also accumulate FDG, thus
resulting in a false-positive study. The radiologist should consider these
alternative benign possibilities, including adenomyomatosis, when confronted
with an FDG PET scan that is positive for uptake in the gallbladder.
References
- Koh T, Tanigichi H, Yamaguchi A, Kunishima S. Differential
diagnosis of gallbladder cancer using positron emission tomography with
fluorine-18-labeled fluoro-deoxyglucose (FDG PET). J Surg
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-81[CrossRef][Medline]
- Rodriguez-Fernandez A, Gomez-Rio M, Llamas-Elvira JM, et al.
Positron-emission tomography with fluorine-18-fluoro-2-deoxy-D-glucose for
gallbladder cancer diagnosis. Am J Surg2004; 188:171
-175[CrossRef][Medline]
- Yoshimitsu K, Honda H, Aibe H, et al. Radiologic diagnosis of
adenomyomatosis of the gallbladder: comparative study among MRI, helical CT,
and transabdominal US. J Comput Assist Tomogr2001; 25:832
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- Raghavendra BN, Subramanyam BR, Balthazar EJ, Horii SC, Megibow AJ,
Hilton S. Sonography of adenomyomatosis of the gallbladder:
radiologic–pathologic correlation. Radiology1983; 146:747
-752[Abstract/Free Full Text]
- Yoshimitsu K, Honda H, Jimi M, et al. MR diagnosis of
adenomyomatosis of the gallbladder and differentiation from gallbladder
carcinoma: importance of showing Rokitansky-Aschoff sinuses.
AJR 1999; 172:1535
-1540[Abstract/Free Full Text]
- Kao CH. Ring-like FDG uptake in acute cholecystitis.
Clin Nucl Med 2003;28
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- Gupta P, Ponzo F, Kramer E. Rim-like FDG uptake in the gallbladder
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Clin Nucl Med 2005;30
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Introduction
Case Report
