A breast biopsy marker is a tiny, metallic clip placed into the breast tissue immediately following a core needle biopsy procedure. These clips are typically made of inert materials like titanium or stainless steel and are smaller than a sesame seed. Placement occurs through the same small incision used for the biopsy, often guided by imaging like mammography, ultrasound, or MRI. The marker’s function is to serve as a permanent, visible reference point for the exact location where the tissue sample was taken.
The marker is not visible or palpable to the patient once the procedure is complete. This standard practice ensures continuity of care for follow-up imaging or potential treatment. Placing a marker addresses the concern that the original suspicious area might shrink or disappear after the biopsy, making it difficult to find later.
The Purpose of Biopsy Markers
These markers function as a radiographic roadmap. They are necessary because removing tissue during a core needle biopsy can sometimes remove the entire abnormality, especially if it was small. Without a marker, the specific location of the lesion may become impossible to pinpoint on subsequent imaging, making precise re-identification of the biopsy site essential.
For cancerous lesions, the marker guides the surgeon during pre-operative localization procedures, such as wire or seed placement, ensuring the correct tissue is removed during a lumpectomy. This precision helps achieve clear surgical margins, preventing the need for repeat operations. Markers are also important if a patient receives chemotherapy before surgery, as the tumor may shrink or vanish, leaving the marker as the only evidence of the original site.
Understanding Marker Movement
Movement, or migration, of a breast biopsy marker is possible, though it is rarely significant enough to compromise care. Markers are designed to stay in place, but they are not anchored, and the surrounding tissue is dynamic. Most displacement occurs immediately following the procedure, within the first hours or days.
The most common mechanism for movement is the “accordion effect.” During a stereotactic biopsy, the breast tissue is compressed. When compression is released, the tissue expands back to its normal shape, which can push the marker along the needle track toward the chest wall or skin surface. A small hematoma, or blood collection, at the biopsy site can also create a space allowing the clip to shift away from the original cavity.
Reported migration rates vary widely, but clinically significant movement—displacement far enough to cause a localization problem—is infrequent. When movement does occur, it is often minimal, usually less than one centimeter. Movement is more likely in areas of the breast with less dense, fatty tissue, which offers less resistance to the clip. Newer generation markers often include a material that expands upon deployment, intended to help secure the metallic clip within the biopsy cavity and reduce the risk of migration.
Clinical Implications of Marker Displacement
When a breast biopsy marker migrates, it rarely jeopardizes the treatment plan because radiologists and surgeons have established mitigation strategies. Professionals compare the post-placement mammogram, which captures the marker’s initial position, with the original images of the suspicious lesion. They use both sets of data, along with current imaging, to triangulate the true location of the original abnormality.
If displacement is suspected, the radiologist can still determine the exact site by noting the marker’s distance and direction of travel relative to fixed anatomical landmarks. The original biopsy cavity is often still visible on ultrasound or MRI, especially immediately after the procedure. This correlation process ensures the target area for follow-up surgery is accurately identified.
Pre-operative localization procedures, such as placing a wire or magnetic seed, reference the historical imaging of the lesion, not solely the current position of the marker. This multi-layered approach ensures the accuracy of surgical excision remains high, supporting the successful removal of the target tissue.
Safety and Permanence of the Marker
Breast biopsy markers are constructed from non-toxic, biologically inert, medical-grade materials such as titanium or stainless steel. These materials do not corrode or degrade and are designed to be permanently compatible with the human body. The marker is intended to remain in the breast indefinitely and does not require removal unless it is taken out during a subsequent surgical procedure, like a lumpectomy.
A common concern is whether the marker is safe for future medical imaging, such as an MRI. Because the materials are non-ferromagnetic, the markers are completely safe for magnetic resonance imaging and do not interfere with the quality of the scan. Their small size and composition also ensure they will not set off metal detectors at airports or security checkpoints. Removal is not standard practice, as they cause no physical symptoms and pose no long-term health risks.