The patient WUQ pain was attributed to a distended gallbladder without convincing imaging features to suggest cholecystitis. The gallbladder neck shows a hypoechoic mass like lesion that appears to be obstructive. Further CT confirmed a hypervascular lobulated mass in the gallbladder neck and the hint for the right differentials is the surgical removal of the left kidney. This patient had a clear cell RCC 5 years ago. Common sites of RCC metastasis are bones, lungs, brain, liver, and adrenal glands ¹. 

The main differentials for this case are metastatic disease and primary gallbladder carcinoma. Given its hypervascularity, the lesion was favored to represent metastasis, as gallbladder malignancies do not commonly show this feature. Although melanoma is a known malignancy to metastasize everywhere and is the most frequent metastasis to the gallbladder ², this patient had an RCC years ago, which is then the favored origin further confirmed histologically.