Which condition is typically evaluated using a breast ultrasound?

A breast ultrasound is specifically designed to differentiate between solid and cystic breast masses. This imaging technique utilizes sound waves to create images of the internal structures of the breast, allowing healthcare providers to see whether a mass is filled with fluid (cystic) or is solid. This distinction is vital because it can influence the management plan and further diagnostic steps. For example, cysts are often benign and may not require further intervention, while solid masses may need additional evaluation, including a biopsy, to rule out malignancy.

The other options, while related to breast health, do not represent primary indications for breast ultrasound. Measuring breast tissue density is typically performed through mammography rather than ultrasound. Assessing lymph node involvement often involves imaging techniques like MRI or CT scans, or sentinel lymph node biopsy, rather than relying on ultrasound alone. While breast pain can sometimes be investigated with ultrasound, the primary goal of the ultrasound is not pain evaluation but rather the characterization of masses. Thus, the ability of breast ultrasound to clearly differentiate between solid and cystic masses establishes it as the correct choice in this context.