Adenomyomatosis of the Gallbladder
Adenomyomatosis is a benign, degenerative condition of the gallbladder characterized by epithelial proliferation and formation of mucosal pouches (Rokitansky-Aschoff sinuses) that penetrate through a thickened muscular layer of the gallbladder wall.
Definition and Pathology
Adenomyomatosis is characterized by:
- Proliferation of the gallbladder mucosal epithelium
- Hypertrophy of the muscularis layer
- Formation of Rokitansky-Aschoff sinuses (RAS) - intramural diverticula or sinus tracts where mucosa invaginates through the thickened muscular wall 1
- These sinuses may contain concentrated bile that can undergo crystal precipitation and calcification 1
Types of Adenomyomatosis
Adenomyomatosis presents in three distinct forms:
- Diffuse - involves the entire gallbladder (least common)
- Segmental - involves a circumferential band of the gallbladder
- Localized (fundal) - most common form, typically affecting the fundus 2
Epidemiology
- Prevalence ranges from 1-9% of the general population 1
- More commonly diagnosed in adults but can rarely occur in children 3
- Represents approximately 4% of all cholecystectomy specimens in some studies 2
Clinical Presentation
Most patients with adenomyomatosis remain asymptomatic, with the condition often discovered incidentally during imaging or after cholecystectomy for other reasons. When symptomatic, patients may experience:
- Dull pain in the right upper quadrant of the abdomen 4
- Symptoms similar to those of chronic cholecystitis
- Symptoms often related to coexisting gallstones (present in up to 84% of cases) 2
Diagnosis
Ultrasound (First-line imaging)
- Primary diagnostic tool showing:
Contrast-Enhanced Ultrasound (CEUS)
- Recommended when RAS cannot be clearly identified on conventional ultrasound
- RAS appear avascular regardless of their content 1, 5
MRI
- Reserved for cases unclear on ultrasound and CEUS
- Highly sensitive for identifying RAS, though signal intensity varies based on content 1, 5
Other Imaging
- PET may help exclude malignancy in selected cases
- CT and cholangiography are not routinely indicated 1
Management
The management approach depends on symptoms and associated conditions:
Asymptomatic adenomyomatosis:
- Observation with ultrasound is appropriate
- No specific follow-up schedule required for mild, incidental cases
- Consider follow-up ultrasound at 6-12 month intervals for 1-2 years to ensure stability
- Extended follow-up beyond 3 years is not necessary unless there are concerning features 5
Symptomatic adenomyomatosis:
When associated with gallstones:
- Cholecystectomy is typically indicated due to the high association with stones (up to 84%) 2
Malignant Potential
While adenomyomatosis is generally considered benign, there are some considerations:
- Rarely, adenomyomatosis may be associated with premalignant changes 4
- Chronic inflammation secondary to lithiasis in adenomyomatosis may lead to dysplastic changes 3
- Prophylactic cholecystectomy may be considered in some cases due to the uncertain nature of the disease and difficult differential diagnosis from malignant lesions 2
Follow-up Recommendations
- Patient education regarding symptoms that should prompt medical attention is crucial
- For asymptomatic cases being monitored, follow-up ultrasound at 6-12 month intervals for 1-2 years is reasonable
- Convert to surgical management if growth is detected, symptoms develop, or concerning imaging features are found 5
Key Points for Clinicians
- Differentiate adenomyomatosis from gallbladder cancer, which can sometimes have similar imaging appearances
- Consider the association with gallstones when evaluating patients
- Recognize that most cases are benign and asymptomatic, requiring no specific intervention
- Cholecystectomy should be reserved for symptomatic cases or when malignancy cannot be excluded