The pearl necklace sign: an imaging sign of adenomyomatosis of the gallbladder at MR cholangiopancreatography

Adenomyomatosis of the gallbladder: the "good omen" comet

BACKGROUND

As emergency physicians perform bedside ultrasound with greater frequency, greater numbers of incidental and potentially unfamiliar sonographic findings will be encountered.

OBJECTIVES

Illustrate, discuss, and briefly review literature regarding one such finding and diagnosis in right upper quadrant sonography.

CASE REPORT

A middle-aged woman was evaluated in the Emergency Department for abdominal pain. Limited bedside sonography of the gallbladder revealed mural thickening and comet-tailing. A diagnosis of adenomyomatosis was made.

CONCLUSION

Gallbladder adenomyomatosis can produce ultrasound findings similar to those of more serious and emergent gallbladder diseases. Cognizance of the sonographic details and typical clinical characteristics will allow the emergency physician to appropriately assess and disposition patients with this condition.

[Imaging in the diagnosis and the staging of gallbladder tumors]

Most of gallbladder tumors are benign. Adenoma, cholesterol polyps, or adenomyomatosis are most frequently typical on ultrasonographic images. All symptomatic lesions must be considered as indications for surgery. It may be difficult to identify precancerous or malignant lesion. Polyps over 1cm are indication for preventive cholecystectomy. In case of suspicious polyp or suspicious wall thickening, endoscopic ultrasonography can be helpful to evaluate local tumoral spread and eliminate differential diagnosis. Unfortunately, diagnosis of gallbladder cancer is often late, when surgical resection can't be curative. Computed tomography and magnetic resonance imaging examinations are then useful for local and metastatic staging.

Analysis of enhancement pattern of flat gallbladder wall thickening on MDCT to differentiate gallbladder cancer from cholecystitis

OBJECTIVE

The objective of our study was to determine the diagnostic value of analyzing the pattern of gallbladder wall enhancement on MDCT to characterize diffuse gallbladder wall thickening as benign or malignant.

MATERIALS AND METHODS

MDCT scans obtained during the portal venous phase in 78 patients with gallbladder wall thickening caused by various pathologic conditions were retrospectively reviewed by two blinded observers. The CT features of benign and malignant gallbladder wall thickening were compared by means of univariate and multivariate analyses. The study cases were then divided into five patterns according to enhancement pattern. Using these five patterns, two radiologists reviewed the MDCT images and recorded their diagnostic confidence for differentiating benign versus malignant cause on a 5-point scale. The diagnostic performance of CT was evaluated by each observer using a receiver operating characteristic curve analysis.

RESULTS

The thicknesses of the inner and outer layers ("thick" enhancing inner layer > or = 2.6 mm, "thin" outer layer < or = 3.4 mm), strong enhancement of the inner wall, and irregular contour of the affected wall were significant predictors for a malignant cause of gallbladder wall thickening (p < 0.001). The two-layer pattern with a strongly enhancing thick inner layer and weakly enhancing or nonenhancing outer layer and the one-layer pattern with a heterogeneously enhancing thick layer were patterns that were significantly associated with gallbladder cancer (p < 0.05). When we consider those two enhancing patterns as a sign of malignancy, the diagnostic accuracy of MDCT was 89.1% and 87.6% for the two observers, respectively.

CONCLUSION

Analyzing the enhancement pattern of a thickened gallbladder wall on MDCT is helpful in differentiating gallbladder cancer from benign inflammatory diseases.

More than just stones: a pictorial review of common and less common gallbladder pathologies

Although stone disease is by far the most commonly encountered pathology of the gallbladder, there are several other important disease processes affecting it. These include adenomyomatosis, cholesterolosis, polyps, porcelain gallbladder, acalculous cholecystitis, xanthogranulomatous cholecystitis, emphysematous cholecystitis, gallbladder cancer, and gallbladder hemorrhage. The purpose of this article was to review the different gallbladder pathologies encountered in everyday radiological practice and to describe their features in the standard imaging modalities.

Imaging of adenomyomatosis of the gall bladder

Adenomyomatosis is a relatively common abnormality of the gall bladder, with a reported incidence of between 2.8 and 5%. Although mainly confined to the adult study group, a number of cases have been reported in the paediatric study group. It is characterized pathologically by excessive proliferation of the surface epithelium and hypertrophy of the muscularis propria of the gall bladder wall, with invagination of the mucosa into the thickened muscularis forming the so-called 'Rokitansky-Aschoff' sinuses. The condition is usually asymptomatic and is often diagnosed as an incidental finding on abdominal imaging. The radiological diagnosis is largely dependent on the visualization of the characteristic Rokitansky-Aschoff sinuses. As the condition is usually asymptomatic, the importance of making a correct diagnosis is to prevent misinterpretation of other gall bladder conditions such as gall bladder cancer, leading to incorrect treatment. In the past, oral cholecystography was the main imaging method used to make this diagnosis. In most institutions, oral cholecystography is no longer carried out, and the diagnosis is now more commonly seen on cross-sectional imaging. In this review article, we describe the manifestations of adenomyomatosis on the various imaging methods, with an emphasis on more modern techniques such as magnetic resonance cholangiopancreatography. A brief section on oral cholecystography to aid readers familiar with this technique in understanding the comparable imaging features on more modern imaging techniques is included.

MR imaging of the gallbladder: a pictorial essay

The gallbladder serves as the repository for bile produced in the liver. However, bile within the gallbladder may become supersaturated with cholesterol, leading to crystal precipitation and subsequent gallstone formation. The most common disorders of the gallbladder are related to gallstones and include symptomatic cholelithiasis, acute and chronic cholecystitis, and carcinoma of the gallbladder. Other conditions that can affect the gallbladder include biliary dyskinesia (functional), adenomyomatosis (hyperplastic), and postoperative changes or complications (iatrogenic). Ultrasonography (US) has been the traditional modality for evaluating gallbladder disease, primarily owing to its high sensitivity and specificity for both stone disease and gallbladder inflammation. US performed before and after ingestion of a fatty meal may also be useful for functional evaluation of the gallbladder. However, US is limited by patient body habitus, with degradation of image quality and anatomic detail in obese individuals. With the advent of faster and more efficient imaging techniques, magnetic resonance (MR) imaging has assumed an increasing role as an adjunct modality for gallbladder imaging, primarily in patients who are incompletely assessed with US. MR imaging allows simultaneous anatomic and physiologic assessment of the gallbladder and biliary tract in both initial evaluation of disease and examination of the postoperative patient. This assessment is accomplished chiefly through the use of MR imaging contrast agents excreted preferentially via the biliary system.

Adenomyomatous Hyperplasia of the Gallbladder With Perineural Invasion

We report 9 examples of segmental adenomyomatous hyperplasia of the gallbladder with perineural invasion. Five patients were women and 4 men. Their ages ranged from 49 to 81 years (mean age 64 y). Eight patients had gallbladder calculi. The original pathologic diagnosis of adenocarcinoma was made in 5 patients and of "adenoma malignum" in one. Six patients are disease-free for 2 to 11 years following cholecystectomy, 1 patient died of unrelated causes and 2 were lost to follow-up. Histologically 2 types of adenomyomatous hyperplasia were recognized. The first one characterized by numerous Rokitansky-Aschoff sinuses (RASs) was accompanied by smooth muscle hyperplasia and an expanded subserosal layer containing numerous nerve trunks (6 cases). The second type was characterized by an extensively fibrotic gallbladder wall with numerous RASs but with few or no smooth muscle bundles and an expanded subserosal layer containing abundant nerve-trunks (3 cases). Perineural (7 cases) and intraneural invasion (2 cases) was identified only in the subserosal layer. The lack of p53 reactivity and the very low MIB-1-labeling index provide additional support to the non-neoplastic nature of the lesion. The pseudoinvasive pattern of the RASs, reactive epithelial atypia, and the perineural and intraneural invasion probably contributed to the erroneous diagnosis of adenocarcinoma or "adenoma malignum." The mechanism by which the epithelial structures "invaded" the perineural spaces and the nerves is unclear. We favor the hypothesis that the migration of the benign glandlike structures into the nerves is related to the production of chemotactic factors or signaling substances and the activation of cell receptors.

CT differentiation of adenomyomatosis and gallbladder cancer

OBJECTIVE

The purpose of this study was to determine the accuracy of CT in differentiating adenomyomatosis from gallbladder cancer.

MATERIALS AND METHODS

We retrospectively identified the cases of 36 patients with pathologically proven adenomyomatosis (n = 22) or gallbladder cancer (n = 14) who had undergone preoperative abdominal CT. Two reviewers independently evaluated the presence and nature of morphologic gallbladder abnormalities, including the presence of intramural diverticula (i.e., small cystic-appearing spaces within the gallbladder wall). The reviewers used a five-point scale (1, definitely absent; 5, definitely present) to rate the overall likelihood of the presence of adenomyomatosis and gallbladder cancer. Ratings were dichotomized such that a diagnosis was considered present at a rating of 4 or 5 and considered absent at lower ratings.

RESULTS

Reviewer 1 detected a morphologic gallbladder abnormality in 17 patients and correctly characterized the abnormality in 14 (82%) of the patients (eight with adenomyomatosis and six with gallbladder cancer). Reviewer 2 detected an abnormality in 18 patients and was correct for 13 (72%) of the patients (eight with adenomyomatosis and five with gallbladder cancer). In particular, reviewer 1 detected intramural diverticula in eight patients, and all had the pathologic diagnosis of adenomyomatosis, whereas reviewer 2 detected intramural diverticula in 11 patients, and eight (73%) had the pathologic diagnosis of adenomyomatosis.

CONCLUSION

CT is limited in the detection and differentiation of adenomyomatosis and gallbladder cancer, but the diagnosis of adenomyomatosis can be made with reasonable accuracy when thickening of the gallbladder wall is seen to contain small cystic-appearing spaces.

Gallbladder adenomyomatosis: imaging findings

In this pictorial essay, we describe the imaging findings of adenomyomatosis of the gallbladder and emphasize high-resolution ultrasound and magnetic resonance cholangiopancreatography in its diagnosis.

Application of modern imaging methods in diagnosis of gallbladder cancer

The poor prognosis of gallbladder cancer (GBC) is related to its dissemination capacity and usually late diagnosis due to its non-specific clinical appearance. Recent improvements in hepatobiliary surgery have underlined the importance of an early specific diagnosis, which requires a multidisciplinary approach and, when possible, specialized equipment. The first step in an early diagnosis is to identify patients in the appropriate epidemiological setting (e.g., incidental finding, chronic cholecystitis) for the correct interpretation of test results. It is desirable to enhance the sensitivity of the initial ultrasound (US) examination by use of the appropriate technology in skilled specialist hands. When GBC is suggested by US findings, FDG-PET can be considered complementary to establish the benign/malignant nature of the lesion and to obtain a primary staging study. If GBC is confirmed, thin slice spiral CT can contribute valuable information on local spread. In this regard, recent hybrid PET-CT systems provide structural and functional information simultaneously and may offer early and accurate T, N, and M staging with an improved specificity.

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Combined segmental and focal adenomyomatosis involving the body of the gallbladder

Adenomyomatosis (adenomyomatous hyperplasia) of the gallbladder is a benign process of unknown origin that has been classified into three morphologic types: diffuse, segmental, and focal (fundal). Cases of combined (segmental and focal) forms involving the gallbladder body are very rare. We present the sonographic findings of a case having adenomyomatosis of the gallbladder body with focal as well as segmental forms of the disease.

Well-differentiated adenocarcinoma of the gallbladder with intratumoral cystic components due to abundant mucin production: a mimicker of adenomyomatosis

The prevalence and etiology of the cystic components within gallbladder carcinomas as seen on MR images were evaluated. A retrospective review of MR images was performed for 35 proven gallbladder carcinomas in search of radiologically detectable intratumoral cystic components. The pathologic specimens were meticulously reviewed to determine the etiology. MR images of 31 adenomyomatoses were also reviewed for comparison to clarify the difference in MR features between these two entities. Three cases out of 35 proven gallbladder carcinomas were found to have intratumoral cystic components. They were all well-differentiated adenocarcinomas, and the cystic components consisted of dilated neoplastic glands filled with abundant mucin pool. Adenomyomatosis tended to have more and rounded cystic components (Rokitansky-Aschoff sinuses) lined in a linear fashion and were flat-elevated in shape, smaller in size and had a regular surface, as compared to the three carcinomas. Although rare, radiologists need to be aware that well-differentiated gallbladder carcinoma with mucin production can have cystic components, which may mimic adenomyomatosis. Careful interpretation of MR images may provide useful information in the differentiation of these two entities.