Which of the following best describes a hypoechoic lesion?

A hypoechoic lesion is characterized by appearing darker than the surrounding tissues on an ultrasound image. This darkness indicates that the lesion reflects fewer ultrasound waves compared to the neighboring structures, making it appear less echogenic. Hypoechoic lesions are often associated with various types of tissue, including fluid-filled areas or solid masses, and the term is used clinically to help in differentiating the nature of the lesion.

Understanding the echogenicity of tissues is key in ultrasound imaging since it assists sonographers in identifying and characterizing lesions. Lesions that are lighter than surrounding tissue are termed hyperechoic, and those that have similar echogenicity are isochoic. Fluid-filled structures typically appear anechoic, meaning they show very little sound reflection, leading to a dark appearance due to the presence of fluid; however, not all hypoechoic lesions are exclusively fluid-filled. Thus, identifying a hypoechoic lesion primarily revolves around its darker appearance relative to nearby tissues.