Which ultrasound description corresponds to a simple liver cyst?

• A. Anechoic with irregular borders
• B. Hyperechoic with posterior shadowing
• C. Anechoic, well-defined border, posterior acoustic enhancement
• D. Septated and echogenic

Answer: (C)

A simple liver cyst appears on ultrasound as anechoic with a smooth, well-defined border and posterior acoustic enhancement. Anechoic means it looks completely black because the fluid inside doesn’t reflect sound waves. The thin, defined wall indicates a benign, uncomplicated cyst, and posterior acoustic enhancement occurs because fluid transmits sound with less attenuation, making the area behind the cyst look brighter. There are no internal echoes, debris, or septations in a simple cyst. The other descriptions imply complexity or solid content—irregular borders suggest a more concerning lesion, hyperechogenicity with shadowing points to solid tissue or calcifications, and septations or internal echoes indicate a complex cyst. Thus, anechoic, well-defined border with posterior enhancement best matches a simple liver cyst.