Breast Biopsy (Stereotactic, Ultrasound-, MRI-Guided)

Breast biopsy removes tissue from a breast lesion so that a pathologist can make a diagnosis before any treatment. It is needed for every lesion that is suspicious on imaging or clinical examination, and for some probably benign lesions.

Three image directed methods are used. Ultrasound directed biopsy is used for masses that can be seen on ultrasound. Stereotactic biopsy uses mammographic or tomosynthesis images and is used for calcifications and for lesions seen only on mammography. MRI-directed biopsy is used for lesions seen only on MRI.

A core needle (14 gauge) or a vacuum assisted device (7 to 12 gauge) is used under local anaesthetic. A core biopsy takes 3 to 5 samples, and a vacuum assisted biopsy takes 6 to 12 or more.

Fine needle aspiration gives cells only and is used mainly for axillary nodes and cysts.

A small metal marker is placed in the biopsy site, so that the area can be found at surgery or follow up.

Core biopsy gives a diagnosis in over 97% of cases, with a false negative rate of under 2 to 3% when the result agrees with the imaging. Vacuum assisted biopsy gives larger samples and is better for calcifications and small lesions.

Needle biopsy has replaced open surgical biopsy in over 90% of cases, because it is accurate, quick, cheaper and leaves a small scar.

Indications.

• A mass, calcifications, distortion or asymmetry that is suspicious on imaging.
• A palpable lump that is solid or complex on ultrasound.
• Enhancement on MRI or contrast enhanced mammography that has no matching finding on other tests.
• A new or growing lesion at short interval follow up.
• Axillary node that looks abnormal, to prove spread before treatment.
• Skin or nipple changes suggesting Paget disease or inflammatory cancer.
• Confirmation of a diagnosis before planning surgery, or before treatment given before surgery.
• Complex cysts, solid papillary lesions and lesions of uncertain nature.
• Recurrence at the site of earlier breast cancer surgery.

Contraindications.

Uncorrected bleeding disorder, anticoagulant therapy that cannot be stopped, allergy to local anaesthetic or adhesive, a lesion too close to an implant, or a patient who cannot lie still. Pregnancy is not a contraindication for ultrasound directed biopsy.

Preparation.

• Informed consent covers the purpose, the steps, the risks of bleeding and infection, and the possibility of repeat biopsy or surgery.
• Medicines: aspirin is usually continued. Warfarin is adjusted so that the INR is within the local limit, and direct oral anticoagulants are held as the local rule requires. Bleeding history is recorded.
• Allergies to local anaesthetic, latex and adhesive are checked.
• Images are reviewed and the target lesion and approach are planned, with attention to the position of the implant and vessels.
• For stereotactic and MRI-directed procedures, the patient must be able to lie prone or sitting for 20 to 45 minutes, and MRI needs renal function and a safety check.
• Skin cleaning with antiseptic, sterile drapes and sterile gloves.
• A chaperone is offered. No fasting is needed.

Technique.

The patient is positioned so that the target is easy to reach: supine or tilted for ultrasound, prone on a table with the breast hanging through an opening for stereotactic biopsy, and prone in the coil for MRI.

The skin is cleaned and local anaesthetic is injected into the skin and along the path.

For ultrasound, the needle is advanced under live imaging and its tip is seen entering the lesion. The device is fired and the samples are taken.

For stereotactic biopsy, two images at different angles give the position of the lesion in three dimensions. The needle is aimed by computer, and a probe is inserted and rotated to take samples around the target.

For calcifications, a specimen radiograph confirms that calcifications are in the samples. For MRI, contrast is injected, the lesion is found, and the needle is placed through a grid or a free hand system. Samples are taken and the lesion's enhancement is checked.

A clip is placed through the needle, and a postprocedure image confirms its position. Pressure is held on the site for 5 to 10 minutes, and a dressing is applied.

Findings on completion.

• Samples of firm tissue that sink in formalin are typical of solid lesions. Fat floats, and a sample made of fat only suggests a missed lesion.
• Calcifications in the sample are seen on the specimen radiograph.
• Final image: the clip is within or next to the target, and any displacement of the clip is measured.
• Histology reports benign tissue, high risk lesions, in situ carcinoma or invasive cancer, with grade, type, and receptor tests on cancers.
• Concordance: the pathologist's report must match the imaging. A benign result in a highly suspicious lesion is discordant, and repeat biopsy or excision is needed.
• High risk lesions (atypical ductal hyperplasia, flat epithelial atypia, lobular neoplasia, radial scar, papillary lesions with atypia) carry a risk of cancer on excision of about 10 to 30%. Excision is usually needed.
• Ductal carcinoma in situ on core biopsy is upgraded to invasive cancer in about 20 to 30% at surgery.
• Benign concordant results: fibroadenoma, fibrocystic change, fat necrosis, sclerosing adenosis. Short interval imaging follows.

Critical findings needing immediate action.

• Cancer: referral to the breast team, multidisciplinary discussion and staging.
• Discordant benign result in a suspicious lesion: repeat biopsy or surgical excision.
• Expanding haematoma, bleeding that does not stop with pressure, or hypotension: pressure, surgical review and a blood test.
• Signs of infection after biopsy: antibiotics, and drainage of an abscess.
• Pneumothorax with breathlessness (very rare, with deep lesions): chest radiograph and drainage.

Complications.

• Bruising and tenderness are usual in 30 to 50%.
• Haematoma needing intervention: about 1% for core biopsy, and up to 3 to 5% for vacuum assisted biopsy, more in patients on anticoagulants.
• Infection: under 1%.
• Vasovagal reaction in 1 to 3%, mainly in the sitting position.
• Pneumothorax: very rare, with a lesion near the chest wall.
• Marker displacement (accordion effect) in up to 20%, and marker migration, which needs the distance to be recorded.
• Inadequate samples or missed lesions, needing repeat biopsy in 2 to 5%.
• Implant damage: rare, with ultrasound direction used to avoid it.
• Tumour seeding along the needle path is very rare and has no clinical effect.
• Anxiety while waiting for the result is common.

Aftercare.

• Pressure for 5 to 10 minutes, then a firm dressing, with an ice pack if useful.
• Avoid strenuous activity and heavy lifting for 24 to 48 hours.
• Paracetamol for pain. Aspirin and anti-inflammatory drugs are avoided for 24 hours unless needed.
• A supportive bra may help comfort for a few days.
• Return if there is rapid swelling, increasing pain, fever, redness or discharge.
• The result is given within a few days at a breast service, with a clear plan.
• Anticoagulants are restarted as the plan given by the team states.
• A clip means the biopsy site can be found later. The patient is told if a clip is placed.

Special groups.

• Women on anticoagulants or antiplatelet drugs: timing and bridging are planned with the prescriber.
• Women with implants: ultrasound direction, with the needle kept parallel to the chest wall.
• Pregnant and breast feeding women: ultrasound directed core biopsy is safe. Milk fistula is a rare risk.
• Men: biopsy of a suspicious mass, with gynaecomastia as the usual finding.
• Women with a high risk gene mutation: MRI-directed biopsy for lesions seen only on MRI.
• Regions: ultrasound directed core biopsy or fine needle aspiration is the usual method, and stereotactic and MRI-directed biopsy are available in few places. Access to pathology and receptor testing is limited.