Chronological changes in the ultrasonic findings of gallbladder metastasis from renal cell carcinoma: a case report and review.

The present case involves a gallbladder metastasis from renal cell carcinoma (GBMRCC). During 11 months of ultrasound follow-up examinations, the mass, covered with a highly echoic surface layer, exhibited the following changes: the wide base became constricted, the tumor surface became irregular, and the mass increased in diameter. A histopathological examination confirmed that the tumor cells were mainly present in the subepithelial layer, the gallbladder epithelium had ruptured, and necrotic debris covered the tumor surface. The highly echoic surface layer observed on the latest ultrasound images corresponded to the necrotic debris. These findings suggested that GBMRCCs initially develop in the subepithelial layer and then undergo expansive intraluminal growth. They subsequently cause the epithelium to rupture, resulting in necrotic debris appearing on the tumor surface.