Types of core biopsy
Core needle biopsy (CNB) is the standard method performed using a spring-loaded device and a 14G needle (smaller diameter needles are less reliable). A single puncture yields a tissue core suitable for histology. Fine-needle aspiration cytology (FNAC) is rarely used today, mainly for evaluating axillary lymph nodes, although 14G is frequently preferred even there.
Vacuum-assisted breast biopsy (VAB) utilizes thick probes (7G–11G) and vacuum suction.
- It enables the retrieval of multiple large specimens (300 mg each) without removing the instrument from the breast (adjacent core samples are obtained by rotating the probe 360 degrees).
- It resolves the issue of sampling error and is indispensable for borderline lesions.
- When biopsying microcalcifications, VAB cuts the risk of missing invasive cancer within a ductal carcinoma in situ area by half compared to CNB.
- It is used for the percutaneous excision of B3 lesions (uncertain malignant potential), avoiding open surgery.
Image-guidance modalities
Since the vast majority of lesions are non-palpable, biopsy requires precise navigation:
- Ultrasound (US). The method of choice, providing real-time guidance. Ultrasound visualizes 80–90% of all abnormalities requiring biopsy.
- X-ray guidance (stereotactic or tomosynthesis). Used for lesions not visible on ultrasound (microcalcifications, architectural distortion). In stereotactic guidance, 3D coordinates (x, y, z) are calculated from two images taken at a 15-degree angle. Equipment includes vertical attachments for mammography units (biopsy sitting or in lateral decubitus) or dedicated tables (patient prone, which reduces the risk of vasovagal syncope).
- MRI guidance. Indicated exclusively for lesions visible only on MRI. The procedure is performed in the prone position with the breast immobilized in a compression grid. VAB is the method of choice here, as it reliably stabilizes the tissue.
Tissue sampling protocols and microcalcification assessment
The volume of retrieved material is strictly regulated:
- For core needle biopsy under ultrasound guidance, a minimum of 2 tissue cores must be obtained.
- For stereotactic biopsy, lesions are harder to identify, so a minimum of 5 cores is required.
If the target of the biopsy is a cluster of microcalcifications, radiography of the retrieved specimens is mandatory (Core Specimen Radiography). The diagnosis is considered reliable only if microcalcifications are radiographically confirmed in at least 3 separate tissue cores, or a total of 5 calcification fragments are found throughout the entire biopsy volume.
Because vacuum-assisted biopsy can completely remove a lesion (especially microcalcifications), a marker must be placed to subsequently identify the intervention site. For example, gel pellets create a mass effect with acoustic shadowing, allowing this zone to be relocated later via ultrasound.
Preoperative localization of non-palpable lesions
If malignancy is confirmed, the surgeon's goal is to excise it with a minimum 5–10 mm margin of surrounding healthy tissue (margins). Without precise localization, excessive tissue volumes are removed, leading to breast deformation. Ultrasound is preferred for navigation.
- Hook wire localization (Hook wire systems). Flexible wires inserted through an introducer. For extensive areas, multiple wires are used to bracket the lesion. Placed on the day of surgery, requiring mandatory follow-up mammography.
- Radioactive seed localization (Radioactive seeds). A wireless method. A titanium pellet containing the I-125 isotope (half-life 60 days) is implanted under imaging guidance up to 30 days before surgery. Localization is performed using an intraoperative gamma probe.
- Magnetic markers (MAGSEED). Metal markers (5 mm) containing iron particles. The intraoperative probe magnetizes them and detects the signal.
The excised specimen also undergoes radiography (Specimen radiography) using surgical orientation clips to confirm clear resection margins.
Briefly: answers to topical questions
What are the absolute and relative contraindications for vacuum-assisted breast biopsy (VAB)?
General contraindications for image-guided biopsy include uncorrected coagulopathy (uncorrected coagulopathy) and the lack of a safe needle pathway.
The presence of bleeding diatheses (bleeding diatheses) and anticoagulant therapy must be checked prior to the procedure. Specific absolute and relative contraindications exclusively for vacuum-assisted biopsy are not detailed in the materials.
What early and late complications may occur following core needle biopsy (CNB)?
The materials do not specify early and late complications exclusively for core needle biopsy, but general complications following image-guided biopsy are described.
These include:
- Hemorrhage (Hemorrhage) is the most frequent major complication.
- Infectious complications — wound infection, deep abscess formation, septicemia, peritonitis.
- Minor complications — post-procedural pain and vasovagal reactions.
- Track seeding (Track seeding) — rare dissemination of malignant cells along the needle tract.
Which histological types of breast cancer are most commonly hidden behind microcalcification clusters?
Microcalcification clusters most frequently harbor invasive breast cancer and ductal carcinoma in situ.
- Invasive breast cancer — may coexist with an area of carcinoma in situ.
- Ductal carcinoma in situ (DCIS) — malignant microcalcifications in DCIS are clustered, have a ductal or linear distribution, and vary in shape and size.
- High-grade ductal carcinoma in situ (High-grade DCIS) — typically manifests as a segmental distribution of pleomorphic microcalcifications (rod-like, branching, granular).
Class and exam questions
Why is vacuum-assisted biopsy (VAB) preferred for microcalcifications?
VAB allows for a large tissue volume to be obtained without repeatedly removing the needle. This reduces sampling errors and halves the risk of missing concomitant invasive cancer in areas of microcalcifications compared to a 14G needle.
What is the principle of stereotactic guidance?
This is an X-ray guidance method in which two images are taken at a 15-degree angle on either side of the central axis to accurately calculate the 3D coordinates (x, y, and z) of a pathological lesion.
What to do if the lesion was completely removed during a microcalcification biopsy?
A marker (metal clip or ultrasound-visible gel pellet) must be placed in the cavity of the excised lesion. This is necessary to localize the area before potential surgical intervention.
What else to study on this topic
- Management of B3 lesions (uncertain malignant potential).
- Features of MRI-guided biopsy: grid-based depth calculation and the gadolinium washout phenomenon.
- Principles of multidisciplinary team (MDT) meetings based on biopsy results.
- Assessment of specimen resection margins using radiography and marking clips.
- Impact of screening programs on breast cancer mortality statistics.
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