Which statement about simple cysts on ultrasound is true?

Which statement about simple cysts on ultrasound is true?

• A. Simple cysts are anechoic with thin walls and posterior enhancement.
• B. Simple cysts have internal echoes.
• C. Simple cysts have mural nodules.
• D. Simple cysts are always malignant.

Answer: (A)

On ultrasound, simple cysts are fluid-filled structures that behave like pure fluid. They appear anechoic, meaning they look completely black inside because fluid does not produce internal echoes. The walls tend to be thin and smooth, and you often see posterior acoustic enhancement—brightness behind the cyst—because sound travels easily through fluid and is less attenuated. Internal echoes would suggest something more complex than a simple cyst, and a mural nodule would indicate a solid component, which is not the case for a simple cyst. Simple cysts are benign, not malignant, so the described appearance—anechoic with thin walls and posterior enhancement—best fits a simple cyst.

On ultrasound, simple cysts are fluid-filled structures that behave like pure fluid. They appear anechoic, meaning they look completely black inside because fluid does not produce internal echoes. The walls tend to be thin and smooth, and you often see posterior acoustic enhancement—brightness behind the cyst—because sound travels easily through fluid and is less attenuated. Internal echoes would suggest something more complex than a simple cyst, and a mural nodule would indicate a solid component, which is not the case for a simple cyst. Simple cysts are benign, not malignant, so the described appearance—anechoic with thin walls and posterior enhancement—best fits a simple cyst.