gallbladder polyps

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Gallbladder polyps and cholesterolosis

Wisam Zakko, MD

Salam F Zakko, MD, FACP

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INTRODUCTION — Gallbladder polyps are outgrowths of the gallbladder

mucosal wall. They are usually found incidentally on ultrasonography

or after cholecystectomy. When detected on ultrasonography, their

clinical significance relates largely to their malignant potential.

The majority of these lesions are not neoplastic but are hyperplastic

or represent lipid deposits (cholesterolosis). On the other hand,

ultrasound characteristics alone are insufficiently specific to

exclude the possibility of gallbladder carcinoma or premalignant

adenomas. Furthermore, even benign lesions can occasionally lead to

symptoms similar to those caused by gallbladder stones.

While the widespread use of ultrasonography has made the diagnosis of

polypoid lesions of the gallbladder increasingly frequent, optimal

strategies for evaluating these lesions have not been established.

This topic review will summarize the clinical significance and

differential diagnosis of gallbladder polyps, and will provide a

practical approach to their management. The discussion will focus on

benign lesions; gallbladder cancer is presented separately.

EPIDEMIOLOGY — Gallbladder polyps have been observed in 0.004 to 13.8

percent of resected gallbladders [1], and to 1.5 to 4.5 percent of

gallbladders assessed by ultrasonography [2,3]. In one report, no

association was observed between the presence of polyps and the

patient's age, sex, weight, number of pregnancies, use of exogenous

female hormones, or any other risk factors that are generally

believed to be associated with gallstones [3]. They have only rarely

been described in children, in whom they occur either as a primary

disorder or in association with other disorders including

metachromatic leukodystrophy, Peutz-Jeghers syndrome, or pancreato-

biliary malunion [4]. (See " Epidemiology of and risk factors for

gallstones " ).

CLASSIFICATION — The classification of gallbladder polyps was first

proposed in 1970 based upon a review of 180 benign tumors [5]. As a

general rule, polypoid lesions can be divided as benign or malignant

(show table 1) [6,7]. Benign lesions are further subdivided into

neoplastic or non-neoplastic.

The most common benign neoplastic lesion is an adenoma. Benign

mesodermal tumors such as leiomyomas and lipomas are rare.

The most common benign non-neoplastic (pseudotumors) are cholesterol

polyps (the presence of which is referred to as " cholesterolosis " ),

followed by adenomyomas (the presence of which is referred to

as " adenomyomatosis " ), and inflammatory polyps [1,5]. Cholesterolosis

and adenomyomatosis are mucosal abnormalities of the gallbladder.

They have been referred to as " hyperplastic cholecystoses, " a term

introduced in 1960 to differentiate them from inflammatory conditions

such as acute cholecystitis since they lack inflammatory features but

exhibit features of hyperplasia [8].

The most common malignant lesion in the gallbladder is

adenocarcinoma. Gallbladder adenocarcinomas are much more common than

gallbladder adenomas in contrast to the colon where adenomas are much

more common than adenocarcinomas. Squamous cell carcinomas, mucinous

cystadenomas, and adenoacanthomas of the gallbladder are rare.

CHOLESTEROLOSIS AND CHOLESTEROL POLYPS — Cholesterolosis has been

recognized since 1857, when Virchow described it in a report on the

role of the gallbladder in fat metabolism [9]. Cholesterolosis is

characterized by the accumulation of lipids in the mucosa of the

gallbladder wall. It is a benign condition that is usually diagnosed

incidentally during cholecystectomy or on ultrasonography. However,

in some patients it can lead to symptoms and complications similar to

those caused by gallstones.