| Gallbladder polyps are usually asymptomatic
lesions which are incidental findings in up to 5% of the population.
The most common type are cholesterol polyps. Cholesterol polyps
account for approximately 50% of all polypoid lesions of the gallbladder.
Cholesterol polyps are generally asymptomatic. Occasionally they
are the cause of biliary colic.
Cholesterol polyps are usually 5 mm or less and only rarely get
bigger than 10 mm.
Other types of gallbladder polyps occur but are less common than
cholesterol polyps. These include adenomas, papillomas, leiomyomas,
lipomas, and neuromas. These lesions are true neoplasms and are
almost always solitary and are usually larger than cholesterol
polyps.
Ultrasound
Ultrasonography is the most effective diagnostic method for detecting
the polypoid lesion of the gallbladder.
The most common type are cholesterol polyps. These are reflective
structures which project into the gallbladder lumen but do not
cast an acoustic shadow. Unless on a long stalk they will remain
fixed on turning the patient and are therefore distinguishable
from stones.
They are attached to the wall by means of a slender stalk. The
stalk is rarely seen so they typically appear as a mass that is
adjacent to the wall but barely attached to the wall : this is
referred to as the "ball on the wall" sign. There are
usually multiple polyps, although it is not uncommon to detect
only the largest one sonographically
They can be distinguished from gallbladder stones by their lack
of a shadow and nonmobile nature and from sludge balls by their
lack of mobility. Their small size and multiplicity help to distinguish
them from true neoplasms of the gallbladder wall.
Supplementary US examination in the harmonic mode is advantageous
: the polyps were more evident on harmonic images and The number
of polyps revealed in US examination is larger in the harmonic
mode..
Larger polyps may have detectable blood flow on color Doppler
imaging
Differential
* Small adherent gallstones,
*Adenomyomatosis,
* Neurofibroma
* Papillomas
* Carcinoma.
* Metastatic disease to the gallbladder is very uncommon but can
produce multiple polypoid lesions. Melanoma has the greatest tendency
to spread to the gallbladder, and detection of gallbladder polyps
should be viewed with a high level of suspicion in patients with
a history of melanoma. Generally there will be other evidence
of metastatic disease in the liver, lymph nodes, or elsewhere
in the abdomen.
Management
Regarding gallbladder polyps, the risk for malignancy is increased
when the lesion is greater than 1 cm especially in patients over
50 years of age. The current recommendations for resection of
gallbladder polyps include any lesion that is enlarging, symptomatic,
or greater than 1 cm. The recommendations for lesions less than
1 cm include follow-up and reevaluation of the lesion via repeat
imaging studies.
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