The ultrasonographic diagnosis of PLG requires the identification of hyperechoic material protruding into the gallbladder lumen (Figures 1 and 2). These echoes are characterized by the absence of shift with positional change; they may or may not cast an acoustic shadow. The sensitivity of ultrasound in detecting PLG ranges from 32% to 90%. Gallstones notoriously decrease ultrasound sensitivity; in patients without gallstones, the sensitivity approaches 99%. The specificity of ultrasound has been reported to be 94%. Other lesions, including sludge, chronic cholecystitis, heterotopic tissue, gallbladder carcinomas and metastatic disease, can be misdiagnosed as benign PLG. The correlation between ultrasonographic and pathological findings in the assessment of PLG has not been clearly defined. Some studies have found a poor correlation between ultrasound findings and pathology. Kubota et al reported accuracies of 89%, 57% and 72% for preoperative sonographic diagnoses of cholesterol polyps, adenomas and carcinomas, respectively, compared with histological findings. In one study of 34 patients who underwent a cholecystectomy for PLG, only 11 had macroscopic and histopatholog-ically proven PLG (thus, a sensitivity of 32%). The size of cholesterol polyps may also be overestimated by ultrasonography. Learn how to save money – buy glucophage to enjoy your shopping and your treatment.
Figure 1) Abdominal ultrasound showing a polypoid lesion of the gallbladder (arrow) with classic sonographic features, including hyper -echogenicity and the absence of an acoustic shadow
Figure 2) Abdominal ultrasound in a patient with two hyperechoic polypoid lesions of the gallbladder (arrows). The gallbladder is otherwise normal
In the differentiation of benign from malignant lesions, recent studies have suggested that colour Doppler ultrasonography in combination with conventional ultrasound may be useful in the diagnosis of PLG. Preliminary reports also suggest that ultrasound-guided percutaneous transhepatic fine needle aspiration is safe and accurate in the assessment of PLG, especially cholesterol polyps. Ultrasonographic angiography may also be helpful in differentiating benign from malignant lesions.