What is adenomyomatosis?

What is Adenomyomatosis?

Adenomyomatosis of the gallbladder is a benign, hyperplastic condition characterized by proliferation of the gallbladder mucosa with invaginations forming intramural diverticula (Rokitansky-Aschoff sinuses) that penetrate through a thickened muscular layer. 1, 2

Pathologic Features

• The condition involves epithelial proliferation and hyperplasia of the muscular layer, with mucosal glandular tissue forming pouches through the thickened gallbladder wall 2, 3
• These mucosal invaginations create characteristic Rokitansky-Aschoff sinuses (RAS), which are large intramural diverticula or sinus tracts visible on imaging 1, 4
• The etiology remains unknown, though it represents a degenerative process rather than a neoplastic one 2, 5

Morphologic Classification

Adenomyomatosis presents in three distinct anatomic patterns:

• Diffuse adenomyomatosis: Involves the entire gallbladder wall (rarest form, approximately 26% of cases) 3, 6
• Segmental adenomyomatosis: Affects a segment of the gallbladder (approximately 26% of cases) 6
• Localized adenomyomatosis: Confined to a focal area, typically the fundus (most common form, approximately 48% of cases) 6

Clinical Presentation

• Most patients with adenomyomatosis remain asymptomatic, making it typically an incidental finding on imaging or histologic examination 2, 6
• When symptomatic, patients present with dull pain in the right upper quadrant, particularly in cases not associated with cholelithiasis 2, 5
• Gallstones are frequently associated with adenomyomatosis (present in approximately 84% of cases), which often dominates the clinical presentation 6
• The condition can occur across all age groups, including children, though it is more commonly diagnosed in adults 4

Diagnostic Approach

• Ultrasound is the imaging modality of choice, with high-frequency probes enabling identification of the characteristic Rokitansky-Aschoff sinuses 1
• If differentiation between tumefactive sludge and adenomyomatosis is challenging, short-interval follow-up ultrasound within 1-2 months with optimized technique is recommended 1, 7
• Contrast-enhanced ultrasound (CEUS) can help distinguish vascular lesions from sludge and should be considered if uncertainty persists 1, 7
• MRI should be considered if CEUS is not available, as it can identify RAS with extremely high sensitivity 1
• CT has inferior diagnostic accuracy compared to CEUS or MRI for characterizing gallbladder lesions 1, 7

Malignant Potential

• While adenomyomatosis has traditionally been considered a benign hyperplastic disease, the possibility of malignant transformation is currently recognized, though it remains very rare 5, 6
• Chronic inflammation and lithiasis secondary to adenomyomatosis may lead to dysplastic changes 4
• The uncertain nature of the disease and difficult differential diagnosis from malignant lesions influences management decisions 6

Treatment Recommendations

• Cholecystectomy is the recommended treatment for symptomatic adenomyomatosis, with laparoscopic approach being the standard of care 1
• The surgical risk is minimal, with morbidity of 2-8% and bile duct injury risk of approximately 0.3-0.6% 1, 7
• Indications for surgery are primarily based on symptoms, though the presence of associated gallstones often drives the decision 6
• For asymptomatic cases without stones, management remains less clearly defined, though prophylactic laparoscopic cholecystectomy may be justified given the evolution and uncertain nature of the disease 6
• Extended follow-up beyond 3 years is not productive according to the Society of Radiologists in Ultrasound consensus 1, 7