CASE 14309 Published on 15.01.2017

Pyloric-type gallbladder adenoma: ultrasound, CT and MRI findings


Abdominal imaging

Case Type

Clinical Cases


Tonolini Massimo, MD (1); Crespi Michele, MD (2); Matacena Giovanni, MD (1)

"Luigi Sacco" University Hospital, Radiology (1) and Surgery (2) Departments
Via G.B. Grassi 74 20157 Milan, Italy;

39 years, female

Area of Interest Biliary Tract / Gallbladder ; Imaging Technique Ultrasound, CT, MR
Clinical History
A middle-aged woman presented with a previous hysterectomy for benign disease, and is currently suffering from alimentary vomiting and upper abdominal pain since 24 hours, without peritonism.
Urgent laboratory tests revealed leukocytosis (24.000cells/mmc), bilirubin 3 mg/dL, hyperlipasemia (1864 U(L), raised C-reactive protein (35 mg/L), aspartate- (747 U/L) and alanine-aminotransferase (786 U/L).
Imaging Findings
Ultrasound (Fig.1) showed a 3.6-cm nonmobile lobulated intraluminal gallbladder mass, isoechoic with the adjacent fatty liver, overlying the continuous non-thickened gallbladder wall.
The next day, CT (Fig.2) showed peripancreatic oedema, normal pancreatic size and enhancement consistent with oedematous acute pancreatitis. The gallbladder mass showed solid precontrast attenuation and moderate enhancement with an identifiable vascular pedicle.
Symptoms and laboratory changes regressed within a week on conservative treatment.
MRI (Figs.3, 4) showed non-dilated common bile duct filling defects consistent with sludge, blood clots or fragments of the gallbladder mass. The latter showed low T2-, low-to-intermediate T1 signal intensity, unrestricted diffusion, moderate and persistent enhancement. The gallbladder wall and adjacent liver parenchyma appeared normal.
Cholecystectomy with en-bloc resection of IVb-V liver segments and nodal dissection was performed. Pathology diagnosed sessile mucosal proliferation with histological features of tubular adenoma with pyloric metaplasia, without signs of dysplasia or malignancy.
Termed gallbladder polyps (GP), lesions protruding into the lumen from the gallbladder wall are encountered in up to 5-7% of the general population, often incidentally during ultrasonographic studies for unrelated reasons. GPs encompass pseudotumours (cholesterol polyps, adenomyomatosis and inflammatory polyps in descending order of frequency), benign and malignant tumours [1, 2].
Gallbladder adenomas (GAs) are rare benign epithelial tumours, which account for approximately 2% of GPs and are found in 0.15% of cholecystectomy specimens. GAs occur in adulthood and advanced age and are asymptomatic, except when obstructing the gallbladder infundibulum; symptoms are generally due to associated lithiasis or chronic inflammation. GAs are almost invariably solitary lesions measuring up to 2 cm in size, and are histologically categorized as pyloric, intestinal, foveolar and biliary. The former type is characterised by dilated glandular structures, metaplastic pyloric-type gastric cells staining positive for mucin, may harbour dysplasia (in 27% of cases) and occasionally foci of carcinoma in larger lesions. Some Authors considered GAs premalignant after observing cases of malignant transformation and Adenomatous residues in invasive carcinomas; conversely recent reports claim that a dysplasia-to-carcinoma sequence is more probable [3-6].
Albeit 95% of GPs are non-neoplastic, radiologists should suggest whether a GP requires surgery, follow-up or nothing; unfortunately the differentiation between benign GPs over 1 cm and protruding forms of gallbladder carcinoma (P-GC) is challenging. Sonographically GAs show homogeneous isoechoic appearance, are confined to the lumen with thin underlying gallbladder wall. CT features suggestive of malignancy include size >1.5 cm, irregular surface, mural thickening, and perception on unenhanced images [7-12].
As this case exemplifies, MRI is helpful in the differentiation of GA from P-GC, the latter characterised by mural thickening, heterogeneously increased T2 signal intensity, prolonged enhancement. Conversely, GA shows moderate homogeneous enhancement with subsequent washout, smooth underlying wall with normal thickness. Diffusion-weighted imaging further improves diagnostic accuracy, since apparent diffusion coefficient (ADC) values of P-GC generally measure 1.31-1.46 and are significantly lower than those of GAs (1.72-2.66 x10-3 mm2/s) [8-10, 13-15].
Accurate imaging is crucial for correct surgical choice and planning. Cholecystectomy is recommended for GPs greater than 1 cm with symptoms, patient age over 50 years, concurrent gallstones or interval growth. Radical surgery including en-bloc resection of adjacent liver and regional lymphadenectomy is required when malignancy cannot be excluded [1,2].
Differential Diagnosis List
Pyloric-type tubular adenoma of the gallbladder.
adherent gallstones/gallbladder sludge ball
Cholesterol polyp
Inflammatory polyp
Protruding type gallbladder carcinoma
Chronic Cholecystitis
Gallbladder lymphoma (rare)
Metastatic gallbladder melanoma (rare)
Final Diagnosis
Pyloric-type tubular adenoma of the gallbladder.
Case information
DOI: 10.1594/EURORAD/CASE.14309
ISSN: 1563-4086