Gallbladder lesions identified on ultrasound. Lessons from the last 10 years.

BACKGROUND: Possible mass lesions identified on ultrasound (US) of the gallbladder may prompt an aggressive surgical intervention due to the possibility of a malignant neoplasm.

AIM: This study aims to utilize a large modern series of patients with gallbladder lesions identified on US to evaluate imaging characteristics consistent with malignancy.

METHODS: A retrospective review was conducted of gallbladder ultrasound reports and clinicopathologic data of patients with a mass identified on US.

RESULTS: Approximately 59,271 abdominal ultrasounds and 9,117 cholecystectomies were performed between February 2000 and February 2010. We identified 213 patients with a questionable gallbladder neoplasm on ultrasonography who underwent surgical exploration. Median age was 52 years (range=11-87 years) and 147 (69%) were females. Final pathology demonstrated no neoplasm in 130 patients (61%), while 32 patients (15%) had a wall adenomyoma, 36 (17%) had a polyp (five of which were malignant), 14 (7%) had an adenocarcinoma not arising from a polyp, and one patient had a cystic papillary neoplasm. The smaller the lesion, the more likely it was to be a pseudo-mass. For lesions measuring <5 mm on US, 83% had no lesion found on final pathology. Significant predictors of malignancy were age >52 years (p<0.001), presence of gallstones on US (p=0.004), size >9 mm (p<0.001), evidence of invasion at the liver interface (p<0.001), and wall thickening >5 mm (p<0.001). Shape (sessile or penduculated), echogenicity (echogenic or isoechoic), or presence of flow on Doppler were not predictors of malignancy. An US size of ≤ 9 mm had a negative predictive value of 100% for malignancy.

CONCLUSIONS: Despite improvements in imaging, most apparent lesions measuring <5 mm on US are not identified in the surgical specimen. US size >9 mm, age >52 years, US suggestion of invasion at the liver interface, and wall thickening >5 mm, especially in the presence of gallstones, should raise the suspicion of malignancy.