Adenomyosis of the gallbladder is a localized change in the mucosal epithelium, myofibrillar hyperplasia and limited adenomyosis, also known as adenomyosis. The pathology is characterized by localized endothelial epithelial adenoid hyperplasia deep into the muscular layer (which can reach the subplasma membrane), forming a wide branching and numerous diverticulum-like cysts, called R-A sinus, also known as R-A sinus, in which bile can accumulate and form stones secondary to infection.
The lesions can be divided into.
1, diffuse type, with diffuse thickening of the entire gallbladder wall.
2. segmental type, in which a circular stenosis appears in the middle part of the thickened gallbladder wall, separating the gallbladder into two small interconnected cavities, so that the gallbladder resembles a gourd.
3, confined (basal type), the wall at the base of the gallbladder shows limited hyperplasia, which is more common in this type.
I. Epidemiology
Since the final diagnosis relies on pathological findings, exact epidemiological information is difficult to obtain, and most of the information comes from imaging screening. The male to female ratio is 1:3, and the age of prevalence is 30-60 years.
Pathogenesis
The etiology of adenomyosis of the gallbladder is not well understood, but most scholars believe that the disease is the result of hypertrophy of the gallbladder wall due to increased mucosal hyperplasia of the gallbladder and smooth muscle hyperplasia, together with abnormal proliferation of nerve fibers in the gallbladder wall, which gradually evolves on the basis of incomplete germinal cystization of the gallbladder. It has been reported that increased gallbladder pressure is associated with the onset of the disease, but some scholars hold a different view that increased gallbladder pressure is the result of adenomyosis rather than the cause.
III. Clinical manifestations and diagnosis
The symptoms of this disease are similar to those of cholecystitis and cholelithiasis without specificity, and they often coexist with these 2 diseases, making the preoperative diagnosis more difficult. The key to diagnosis is to have a certain understanding of the disease, be familiar with the pathological typology of the disease and the characteristic manifestations of oral cholecystography, and to combine ultrasound, CT and other imaging examinations for comprehensive analysis to improve the diagnosis. Imaging findings R-A sinus is specific for the diagnosis of this disease.
1.Ultrasound examination
Ultrasound image features are.
(1) Significant thickening of the gallbladder wall, with limited, segmental or diffuse changes. (1) Significant thickening of the gallbladder wall, in the form of limited, segmental or diffuse changes, with the lesions mostly located at the bottom of the gallbladder and showing cone-cap thickening. In the segmental type, the thickened wall of the cyst protrudes into the lumen to form the so-called “triangular sign”, and the cystic cavity narrows and takes on a “gourd” shape or even closes completely. In the diffuse type, the wall of the gallbladder is diffusely and centripetally thickened, the mucosal and plasma layers are continuous and intact, and the inner wall is uneven.
(2) Echo-free dark areas or echogenic enhancement areas (cholesterol deposits) are seen within the thickened gallbladder wall.
(3) Combined interstitial stones, gallbladder stones, gallbladder polyps, etc. may show corresponding image changes.
(4) Color Doppler shows no significant blood flow signal in the thickened gallbladder wall.
(4) Color Doppler shows no significant blood flow signal within the thickened gallbladder wall. Small cystic hypoechoic or anechoic areas or comet-tailed strong echogenicity are characteristic of gallbladder adenomyosis and are highly specific for the diagnosis of this disease. In some patients, due to the small R-A sinus that cannot be shown by ultrasound, the image only shows uneven echogenic thickening of the gallbladder wall, which is more difficult to diagnose and needs to be differentiated from chronic cholecystitis and gallbladder cancer. Gallbladder adenomyosis shows a clear and smooth border with continuous plasma membrane and mucosal layer, while chronic cholecystitis generally has a homogeneous thickening of the gallbladder, which is more regular, with a thickness of <5mm and a weakened contractile function of the gallbladder. In gallbladder cancer, the gallbladder has irregular margins, disproportionate thickening, nodular or irregular elevations on the wall, abnormal blood flow signals inside, and in some cases, enlarged lymph nodes may appear in the neck, which can be differentiated. In addition, some atypical localized adenomyosis resembles polyps or adenomas, which are difficult to distinguish by ultrasound.
2.MRI
CT and MRI can show diffuse or limited thickening of the gallbladder wall, and the thickened wall is often larger than 5 mm or the R-A sinus can be seen. The so-called “two-ring sign” or “three-ring sign” is a sign of two or three “concentric circles” formed by the hyperplastic smooth muscle tissue reinforced with the non-enhanced inner lumen of the gallbladder and the slightly reinforced outer layer of the gallbladder wall with a slightly low density shadow. MRI enhancement can clearly show early enhancement of the mucosal layer and delayed enhancement of the plasma layer. One of the advantages of MRI compared with CT is that it can clearly show the smaller R-A sinuses, even without contrast enhancement, in the T2WI sequence. Gallbladder adenomyosis should be differentiated from gallbladder cancer and chronic cholecystitis on imaging. Gallbladder cancer may appear as a mass protruding into the gallbladder cavity, with irregular thickening of the gallbladder wall, and the edge of the tumor is often poorly defined. Chronic cholecystitis shows fibrosis of gallbladder wall, shrinkage of gallbladder cavity, homogeneous thickening of gallbladder wall, no focal thickening, and no R-A sinus display.
3.Differential diagnosis
This disease needs to be differentiated from other gallbladder diseases.
The limited type should be distinguished from gallbladder cancer and gallbladder polyps; the diffuse type should be distinguished from chronic cholecystitis; the segmental type should be distinguished from congenital septum of gallbladder, distortion and folding of gallbladder. In patients with post-feeding cholecystic adenomyosis, the gallbladder is hypercontracted, and the lipid meal test is different from that of cholecystitis and gallbladder carcinoma, and the latter two often have poorly contracted gallbladder in the lipid meal test.
IV. Treatment
Drug treatment can only relieve the symptoms, but complete treatment requires cholecystectomy. The key lies in the selection of surgical indications, and there is no uniform standard. Some scholars believe that adenomyosis of gallbladder is a precancerous lesion of gallbladder cancer and is easily complicated by gallbladder stones, therefore, surgery should be performed immediately upon diagnosis. Some scholars consider suspected cancer or combined with stones as indications for surgery.
Since the diagnosis of this disease ultimately relies on pathology, preoperative diagnosis is difficult and relies entirely on imaging. Imaging indications highly suggestive of gallbladder adenomyosis as well as the need for surgery should be established, such as reports that suggest a non-inflammatory thickening or irregular thickening of the gallbladder wall on ultrasound; 5 mm should be highly suspicious of gallbladder adenomyosis.