What Is a Breast Biopsy?

A breast biopsy is a medical procedure in which tissue is removed from a suspicious area of the breast and examined under a microscope to determine whether it is benign or malignant. It is the definitive step in diagnosing breast abnormalities identified by imaging, physical examination, or screening programs. Biopsy techniques range from fine-needle aspiration, which collects cells with a small-gauge needle, to surgical excision, which removes the entire lesion. The dominant methods in contemporary practice are minimally invasive percutaneous techniques, in which a needle is guided into the target lesion using real-time or registered imaging, reducing patient recovery time compared to open surgery. Breast biopsy sits at the intersection of life sciences, medical imaging, and interventional device engineering.

The accuracy of a biopsy depends on precise needle placement, adequate tissue sampling, and correct histopathological interpretation. Image guidance has been central to improving that accuracy, with ultrasound, mammographic, and MRI guidance each addressing different classes of lesions that would otherwise be difficult to target reliably.

Core Needle Biopsy

Core needle biopsy is the standard percutaneous technique for characterizing solid breast masses. A hollow cutting needle, typically 14 to 11 gauge, is advanced into the target lesion and fired rapidly to capture a cylindrical core of tissue. Multiple cores, usually 6 to 12, are obtained and evaluated histopathologically for tumor type, grade, hormone receptor status, and other biomarkers that guide treatment planning. The American Cancer Society describes core needle biopsy of the breast as the preferred approach for most palpable and image-identified lesions because it provides adequate tissue for receptor testing while preserving normal surrounding tissue. Overall diagnostic accuracy for core needle biopsy exceeds 96%, comparable to surgical excision for the vast majority of cases.

Stereotactic and Ultrasound-Guided Techniques

Stereotactic biopsy uses paired mammographic X-ray images taken at different angles to calculate the three-dimensional coordinates of the target lesion, then guides the needle to that calculated position. It is the preferred method for targeting microcalcifications and non-mass-forming lesions that are visible on mammography but not detectable by ultrasound or palpation. A study in PMC on the accuracy of ultrasound, stereotactic, and clinical core biopsies found overall stereotactic accuracy of 97%, on par with needle-localized surgical biopsy. Ultrasound-guided biopsy, by contrast, uses real-time sonographic imaging to visualize the needle tip advancing toward the lesion, providing continuous confirmation of needle position and allowing sampling along multiple axes. It is faster, less expensive, and more comfortable than stereotactic approaches for lesions visible on ultrasound.

Vacuum-Assisted and MRI-Guided Biopsy

Vacuum-assisted biopsy devices use a rotating cutting aperture and applied suction to draw tissue into the sampling chamber, collecting larger samples in a single needle insertion than conventional core needles. The larger sample volume reduces under-sampling errors and is particularly useful for small or architecturally subtle lesions. MRI-guided biopsy addresses lesions visible only on contrast-enhanced MRI, using a dedicated breast coil and a grid-based or robotic targeting system to place the needle while the patient remains in the scanner. As described in the RadiologyInfo.org overview of stereotactic breast biopsy, a biopsy marker clip is placed at the biopsy site after sampling in all image-guided procedures, providing a permanent reference for follow-up imaging and surgical planning.

Applications

Breast biopsy techniques are used in a range of clinical and research contexts, including:

• Pathological confirmation of breast cancer before systemic or surgical treatment
• Assessment of receptor status (estrogen receptor, HER2) for targeted therapy selection
• Evaluation of benign proliferative lesions such as atypical ductal hyperplasia
• Post-treatment monitoring and assessment of residual disease
• Research tissue banking for molecular and genomic studies of breast cancer subtypes