Adenom der Gallenblase

Gallbladder adenomas are uncommon gallbladder polyps that, although benign, have a premalignant behavior.

Terminology

As the distinction of adenomas and intracholecystic papillary-tubular neoplasms (ICPN) is not entirely clear, with important overlap between both entities, some authors have proposed that all the adenomas over 1 cm should be grouped under the ICPN terminology . A note is made that the last WHO classification is from 2010, therefore, proceeding these publications.

Epidemiology

Adenomas make 4% to 7% of all gallbladder polyps . They are incidentally found in about 0.5% of the gallbladder specimens .

There is a 2.4:1 female-to-male prevalence ratio .

Associations

Increased prevalence of gallbladder and biliary tract adenomas occurs in :

Pathology

Macroscopic appearance

They are polypoid structures projecting into the gallbladder lumen usually measuring less than 2 cm in size, and showing either a sessile or pedunculated appearance. In about 10% of the cases, adenomas are multiple .

Microscopic appearance 

Gallbladder adenomas are classified in :

  • tubular adenomas
    • the most common
    • composed by pyloric-type glands: cuboidal or columnar cells containing vesicular or hyperchromatic nuclei and covered by biliary epithelium
    • or by intestinal-type glands: with pseudostratified columnar epithelium covered by biliary epithelium
  • papillary adenomas
    • papillary structures lined by cuboidal or columnar cells
  • tubulopapillary adenomas
    • subtype characterized when both the tubular glands and the papillary formations each corresponds to more than 20% of the tumor

Radiographic features

There are no reliable imaging features to distinguish adenomas from gallbladder adenocarcinomas . They might be associated with gallstones or features of chronic cholecystitis.

Ultrasound

Adenomas are usually solitary gallbladder wall lesions that can have a sessile, pedunculated, or polypoid appearance.

  • usually hypoechoic with no posterior acoustic shadowing
  • variable size, usually between 5 mm to 20 mm
  • may have a lobulated or cauliflowerlike contour
  • in the pedunculated lesions, the stalk might be difficult to visualize and might require changes in the patient decubitus 
  • internal vascularity at color Doppler may be demonstrated
  • focal gallbladder wall thickening adjacent to the polyp is a worrisome feature concerning for malignancy
  • CEUS: enhancement is seen in the arterial phase
CT

They might be distinguished as small hypodense intraluminal gallbladder lesions that demonstrate enhancement .

Treatment and prognosis 

Gallbladder adenomas are usually managed surgically. Please refer to the parental article on gallbladder polyps for guidelines on when followup or surgery should be considered.

Differential diagnosis

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