Is Adenomyomatosis of the Gallbladder Malignant?
Adenomyomatosis of the gallbladder is a benign condition, not a malignancy. 1
What Adenomyomatosis Actually Is
Adenomyomatosis is defined as mural hyperplasia (benign overgrowth of the gallbladder wall) that may be diffuse, focal, or segmental, characterized by:
- Rokitansky-Aschoff sinuses (intramural cysts/diverticula) 1
- Comet-tail artifact on gray-scale ultrasound or twinkling artifact on color Doppler imaging due to intramural cholesterol crystals 1
- Wall thickening containing small bile-filled cystic spaces 2
This is fundamentally a hyperplastic benign disease, not a neoplastic or malignant process. 3, 4
Critical Distinction from Malignancy
The Society of Radiologists in Ultrasound 2022 guidelines explicitly categorize adenomyomatosis as a benign entity that must be distinguished from true gallbladder polyps and malignancies. 1
Key differentiating features:
- Adenomyomatosis shows characteristic imaging artifacts (comet-tail, twinkling) that gallbladder cancer does not 1, 5
- At contrast-enhanced ultrasound (CEUS), adenomyomatosis demonstrates avascular Rokitansky-Aschoff sinuses, unlike the marked early enhancement seen in neoplastic lesions 5, 2
- MRI shows the pathognomonic "pearl necklace" appearance of Rokitansky-Aschoff sinuses 4
The Controversial Association with Cancer
Important caveat: While adenomyomatosis itself is benign, there is emerging evidence of a potential association with gallbladder cancer development:
- Some studies suggest adenomyomatosis may predispose to gallbladder malignancies, though this remains controversial 3, 6
- One study found that 25.8% of surgically treated gallbladder carcinomas had gross features of adenomyomatosis, and these cancers were more often diagnosed at advanced stages 7
- The hypothesis is that preceding adenomyomatosis may mask early detection of gallbladder cancer rather than directly causing malignancy 7
However, adenomyomatosis is still classified as a benign condition despite these reports. 3
Management Approach
For symptomatic adenomyomatosis:
For asymptomatic adenomyomatosis:
- No surgery required if the radiological diagnosis is certain 4
- Wait-and-see policy is viable for low-risk patterns (particularly fundal type) with scheduled follow-ups 3
- Exception: If there is any diagnostic doubt about possible gallbladder cancer, cholecystectomy is justified 6, 4
Patterns requiring heightened vigilance:
- Segmental type adenomyomatosis was associated with 64% of adenomyomatosis-positive gallbladder cancers in one series 7
- Diffuse type appears less concerning 7
Bottom Line
Adenomyomatosis is definitively benign, but the diagnostic certainty must be absolute—if imaging cannot confidently exclude malignancy, surgical resection is warranted. 6, 4