Adenomyomatosis is a benign, non-neoplastic condition of the gallbladder wall characterized by epithelial proliferation and muscular hypertrophy. Rokitansky-Aschoff sinuses (RAS) — herniation of the gallbladder mucosa into the muscularis layer — are the pathologic hallmark of this disease. The gallbladder wall becomes thickened and sinuses may contain bile, mucin, or cholesterol crystals. Prevalence is reported as 2-9% in cholecystectomy specimens and is more common in women. Adenomyomatosis is not considered a premalignant condition, although the segmental form with focal wall thickening can mimic gallbladder carcinoma. On ultrasound, comet-tail artifacts arising from Rokitansky-Aschoff sinuses are pathognomonic for diagnosis.
Age Range
30-70
Peak Age
50
Gender
Female predominant
Prevalence
Uncommon
Adenomyomatosis develops through hypertrophy of the muscular layer of the gallbladder wall and herniation of the mucosa through this hypertrophic muscle layer (Rokitansky-Aschoff sinuses). The pathophysiology is fundamentally driven by increased intraluminal pressure and chronic irritation in the gallbladder, leading to compensatory muscular thickening. RAS can fill with bile, cholesterol crystals, and mucin. Cholesterol crystals act as strong acoustic reflectors on ultrasound and produce comet-tail artifacts (V-shaped reverberation artifacts) — this results from multiple internal reflections of sound waves between crystals. On MRI, T2-weighted sequences show RAS as small high-signal foci within the wall ('pearl necklace' pattern), reflecting the fluid content of the sinuses. On CT, small hypodense cystic foci within the thickened wall correspond to non-enhancing RAS.
V-shaped reverberation artifacts arising from cholesterol crystals accumulated in Rokitansky-Aschoff sinuses of the gallbladder wall. Results from multiple internal reflections of sound waves between flat crystal surfaces. Pathognomonic for adenomyomatosis and not seen in gallbladder carcinoma.
Comet-tail artifacts (V-shaped reverberation artifacts) arising from Rokitansky-Aschoff sinuses containing cholesterol crystals in the gallbladder wall. These artifacts are seen with wall thickening and are usually most prominent at the fundus. Artifacts are short, triangular, bright structures extending distally from echogenic foci. In the diffuse type they appear throughout the wall, in the focal type in a single region, and in the segmental type as an annular band.
Report Sentence
Multiple comet-tail artifacts are identified within the gallbladder wall, consistent with Rokitansky-Aschoff sinuses; findings support the diagnosis of adenomyomatosis.
Focal or diffuse gallbladder wall thickening (>3 mm) with small anechoic-hypoechoic cystic foci within the wall. These cystic foci correspond to Rokitansky-Aschoff sinuses filled with bile or mucin. Wall thickening is usually smooth contoured with an intact mucosal surface. In the fundal type, thickening is confined to the fundus, while in the segmental type, an annular constriction is seen at the body.
Report Sentence
Gallbladder wall thickening with intramural small cystic foci is identified, suggestive of Rokitansky-Aschoff sinuses consistent with adenomyomatosis.
Small high-signal foci arranged within the gallbladder wall on T2-weighted MRI — 'pearl necklace' sign. These foci correspond to fluid-filled RAS and appear as bright dots against the background of thickened hypointense muscular layer. The pearl necklace pattern is highly specific for adenomyomatosis and plays a critical role in differential diagnosis from gallbladder carcinoma wall thickening. In diffuse type it appears throughout the wall, in fundal type only at the fundus, and in segmental type as an annular band at the body.
Report Sentence
Small high-signal intramural foci in a 'pearl necklace' pattern are identified within the gallbladder wall on T2-weighted sequences, consistent with adenomyomatosis (Rokitansky-Aschoff sinuses).
Smooth contoured gallbladder wall thickening with small hypodense cystic foci within the wall on contrast-enhanced CT. RAS do not enhance and show lower density than the surrounding enhancing muscular tissue. Mucosal enhancement is regular and preserved — no mucosal irregularity or invasion. In the segmental type, annular thickening at the body divides the gallbladder into two compartments ('hourglass' appearance). Pericholecystic fat planes are clean with no evidence of inflammatory or neoplastic process.
Report Sentence
Smooth contoured gallbladder wall thickening with small non-enhancing hypodense foci within the wall is identified on contrast-enhanced CT, consistent with adenomyomatosis.
Adenomyomatosis does not show diffusion restriction on diffusion-weighted MRI. No signal loss is seen in the area of wall thickening on the ADC map, with values remaining within normal range. This finding is important in differential diagnosis from diffusion restriction seen in gallbladder carcinoma (low ADC values). In gallbladder carcinoma, increased cellularity restricts water molecule movement producing low ADC values, while in adenomyomatosis, edema and fluid-filled RAS produce high ADC values.
Report Sentence
No diffusion restriction is detected in the area of gallbladder wall thickening with ADC values within normal range; this finding does not support a malignant process.
Small high-signal foci within the gallbladder wall may be seen on precontrast T1-weighted images. These foci are due to the T1-shortening effect of concentrated bile or cholesterol crystals accumulating within RAS. Not seen in all cases, but when present, supports the diagnosis of adenomyomatosis. On post-gadolinium images, these foci do not enhance and can be distinguished from the enhancing surrounding wall.
Report Sentence
Small high-signal intramural foci within the gallbladder wall on precontrast T1-weighted sequences are consistent with Rokitansky-Aschoff sinuses containing concentrated bile or cholesterol.
MRCP sequences prominently demonstrate small high-signal cystic foci within the gallbladder wall. The heavily T2-weighted nature of MRCP clearly separates fluid-filled RAS from surrounding solid tissue. These foci may show continuity with the gallbladder lumen or appear isolated. MRCP is also useful for evaluating concomitant biliary pathology (cholelithiasis, choledocholithiasis).
Report Sentence
Small high-signal intramural cystic foci within the gallbladder wall on MRCP sequences are consistent with Rokitansky-Aschoff sinuses, a finding of adenomyomatosis.
Criteria
Adenomyomatosis changes are confined to the gallbladder fundus. The most common form, accounting for approximately 50% of cases.
Distinct Features
Focal polypoid thickening at the fundus can mimic gallbladder polyp. Comet-tail artifacts and intramural cystic foci support benign nature. Fundal pearl necklace pattern on MRI is diagnostic.
Criteria
Annular band of adenomyomatosis at the gallbladder body. Ring-like constriction at the body divides the gallbladder into two compartments ('hourglass' appearance). Accounts for ~25% of cases.
Distinct Features
Annular constriction can mimic gallbladder carcinoma. Recognition of the hourglass appearance and demonstration of RAS foci are critical for differential diagnosis. Increased predisposition to bile stasis and gallstone formation in the distal compartment.
Criteria
Adenomyomatosis changes are diffusely present throughout the entire gallbladder wall. Accounts for ~25% of cases. Diffuse wall thickening and widespread RAS foci throughout.
Distinct Features
Diffuse wall thickening can mimic chronic cholecystitis or infiltrative carcinoma. Widespread comet-tail artifacts and pearl necklace pattern on MRI support benign diagnosis. Absence of diffusion restriction on DWI helps exclude malignancy.
Distinguishing Feature
Comet-tail artifact is NOT seen in gallbladder carcinoma; mucosal irregularity, invasion, and diffusion restriction are observed. In adenomyomatosis, mucosa is regular, RAS foci are present, and no diffusion restriction.
Distinguishing Feature
In chronic cholecystitis, wall thickening is smooth but RAS foci and comet-tail artifacts are absent. Usually accompanied by gallstones. In adenomyomatosis, intramural cystic foci and comet-tail artifacts are diagnostic.
Distinguishing Feature
In xanthogranulomatous cholecystitis, nodular thickening, intramural nodules, and pericholecystic inflammation are prominent. RAS foci and pearl necklace pattern are absent. In adenomyomatosis, pericholecystic changes are minimal and intramural cystic foci are diagnostic.
Distinguishing Feature
Gallbladder polyps show solid structures projecting into the lumen, without acoustic shadow or comet-tail artifacts. Fundal adenomyomatosis may appear polypoid, but comet-tail artifacts and intramural cystic foci distinguish adenomyomatosis.
Urgency
routineManagement
conservativeBiopsy
Not NeededFollow-up
no-follow-upAdenomyomatosis is a benign condition and is not considered premalignant. No treatment is needed in asymptomatic patients and follow-up is not recommended. In symptomatic patients or to exclude gallbladder carcinoma, cholecystectomy may be performed. Incidental detection in surgical pathology is common (2-9% of cholecystectomy specimens).
Adenomyomatosis is benign and usually requires no treatment. However, the focal form can mimic gallbladder carcinoma. Pathognomonic findings on MR and US (pearl necklace, comet-tail) support the diagnosis. Segmental form may cause luminal narrowing leading to biliary symptoms.