Breast Stereotactic Core Biopsy/Fine Needle Aspiration

Updated: Aug 09, 2018
  • Author: Hemant Singhal, MD, MBBS, MBA, FRCS, FRCS(Edin), FRCSC; Chief Editor: Meda Raghavendra (Raghu), MD  more...
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The establishment of national breast-screening programs in Europe and North America led to an increase in the detection of small or impalpable breast lesions. The ability to achieve an accurate histopathologic diagnosis of these lesions is crucial to any screening program in terms of appropriate treatment planning and patient counseling.

Stereotactic breast needle biopsy refers to the sampling of nonpalpable or indistinct breast lesions by using techniques that enable the spatial localization of the lesion within the breast. The word stereotactic is derived from Greek and Latin roots meaning "touching in space." Stereotactic techniques have evolved in parallel with the trend in breast conservation and minimally invasive surgery.

In the past, impalpable breast lesions would have been surgically excised after needle localization, resulting in a vast number of surgeries for nonmalignant mammographic abnormalities. In the United States, it is estimated that more than a million surgical breast biopsies are performed, and in only 15%-30% are the samples subsequently found to be malignant.

Role of stereotactic needle biopsy

Compared with open surgical biopsy, needle biopsy causes less trauma and disfigurement and is performed as an outpatient procedure with the patient under local anesthetic. [1]  Stereotactic needle biopsy is an important tool in the diagnosis of breast lesions as part of the triple assessment, which includes clinical, radiologic, and cytohistopathologic studies. [2]

Definitively diagnosing these lesions with needle biopsy has several advantages. For benign lesions, establishing a definitive diagnosis obviates unnecessary surgical excision or protracted follow-up, both of which are costly in psychosocial and resource terms. [1, 3, 4, 5, 6]  A definitive diagnosis of cancer allows the patient to make an informed choice and to obtain counseling before surgery. It also facilitates in the planning of multimodal treatment in terms of neoadjuvant chemotherapy, the type of procedure, and early or delayed reconstruction.

The importance of achieving preoperative diagnosis is further emphasized in the quality objectives of the United Kingdom's national breast-screening program to minimize unnecessary benign surgical biopsy and to ensure that more than 70% of women with cancer have a preoperative diagnosis. [7]

Techniques and principles of stereotaxis

Because most of the lesions detected during screening are impalpable, subsequent needle biopsy must be image-guided. Ultrasonography-guided biopsy is usually the most straightforward approach, but lesions better seen on mammography images, particularly microcalcifications, require stereotactic localization.

The principles of localization involve mapping the distance between the geometric center of the breast with the target lesion in two different planes and then projecting the coordinates onto the patient's breast (see image below).

Stereotactic images obtained during a prone-table Stereotactic images obtained during a prone-table biopsy procedure.

Earlier techniques in stereotaxis used mammographic projections to localize the target lesion within the breast. Advances in digital mammography have since superseded manual computations. Dedicated stereotactic equipment that performs localization with fixation of the breast is now in use (see image above). [8, 9, 10, 11]  Stereotactic techniques have also been developed within other imaging modalities, including ultrasonography and magnetic resonance imaging (MRI). These techniques offer more options and greater flexibility in performing stereotactic biopsy.

Digital tomosynthesis creates a three-dimensional (3-D) picture of the breast using x-rays. It has been approved by the US Food and Drug Administration (FDA), but it is not yet considered the standard of care for breast care screening and is only available in limited hospitals. It takes multiple x-ray pictures of each breast from many angles. The breast is positioned in the same way as conventional mammography but with limited pressure. The x-ray tube moves in an arc around the breast while numerous images are taken within a few seconds. The information is then relayed to a computer, which generates highly focussed 3-D images throughout the breast.

In 2013, Hologic Inc launched the world's first 3-D breast biopsy option "Affirm 3D". The procedure can be of benefit in targeting lesions that cannot be easily detected on two-dimensional (2-D) imaging or when using other modalities. It is claimed to also target lesions faster and reduce patient procedure time.

Relevant Anatomy

The breast is made up of fatty tissue and glandular, milk-producing tissues. The ratio of fatty tissue to glandular tissue varies among individuals. In addition, with the onset of menopause (ie, decrease in estrogen levels), the relative amount of fatty tissue increases as the glandular tissue diminishes.

The base of the breast overlies the pectoralis major muscle between the second and sixth ribs in the nonptotic state. The gland is anchored to the pectoralis major fascia by the suspensory ligaments first described by Astley Cooper in 1840. These ligaments run throughout the breast tissue parenchyma from the deep fascia beneath the breast and attach to the dermis of the skin. Since they are not taut, they allow for the natural motion of the breast.

For more information about the relevant anatomy, see Breast Anatomy.


Indications and Anesthesiology


The main application of stereotactic needle biopsy is in sampling nonpalpable breast lesions. It also has an important role in the biopsy of small, indistinct lesions, particularly those occurring in association with surgical scarring, fibrosis, or prosthetic implants. [12, 13]

A further indication is for repeat biopsy in cases in which previous biopsy results are inconclusive. This situation often occurs when the tumor has both benign and malignant or preinvasive components.


Local anaesthesia is mainly used for stereotactic biopsy.



Although core biopsy under ultrasonographic guidance has traditionally been the first choice for diagnosis of most breast lesions, [14]  and it has improved the accuracy of image-guided needle biopsy in the diagnosis of impalpable lesions, the problems with underestimation and the potential for sampling error has led to more invasive and larger-volume percutaneous biopsy devices. The two main types are (1) vacuum-assisted biopsy devices, such as the Mammotome device and the Hologic ATEC device, and (2) image-guided single-cylinder excision alternatives, such as the INTACT device. The common denominator of these devices is their ability to sample larger tissue volumes.

The Mammotome probe, for example, consists of an outer shell with an aperture at its end for collecting tissue. It is a single-insertion device that uses vacuum suction to pull the target tissue into the collecting aperture. The tissue is then excised by a rotating cutter. Multiple harvests can be performed 360º around the lesion while the probe remains in the lesion during the whole procedure.

The vacuum device can be used under ultrasonographic guidance or stereotactic guidance, particularly for microcalcifications [14, 15] ; the patient is prone or upright with the use of certain units, with adequate room to accommodate the device. The vacuum devices are available in different sizes (eg, the Mammotome is available in 11g and 8g, the ATEC in 12g and 9g, and the Encor in 10g and 7g).

The vacuum device has been demonstrated to be superior in the diagnosis of DCIS compared with a 14-gauge core biopsy, with 6% of vacuum-biopsy ductal carcinoma in situ (DCIS) found to be invasive carcinoma at surgery compared with 21% with 14-gauge core biopsy. [16, 17]  Repeat biopsy rates for inadequate sampling of microcalcifications is also significantly lower when using vacuum biopsy (11.6%) compared with core biopsy (23.7%), although an equal proportion of malignancy is diagnosed following rebiopsy. [18]  Although vacuum biopsy appears to be nearly three times more accurate than core biopsy in the diagnosis of atypical ductal hyperplasia (ADH), underestimation still occurs in 18%-25% of cases. [19, 20]

Because vacuum biopsy removes more tissue during sampling than core biopsy, complete removal of the mammographic abnormality has been reported [17, 21] ; however, this is not always correlated with removal of the pathologic lesion at surgery. [16]  A localizing clip can be inserted if the mammographic lesion is small; this clip can potentially be removed during vacuum biopsy. Thus far, no cases or tumor track seeding has been described, although benign epithelial displacement has been described. [22]  The likelihood of this occurrence is probably minimized if the operator chooses to insert the probe into position rather than fire it into place.



Fine needle aspiration biopsy

Although fine-needle aspiration (FNA) is no longer the criterion standard for initial evaluation of all palpable breast masses, it is particularly useful in the evaluation of cystic lesions detected by ultrasonography. [23]

FNA results are reported as benign, suggestive of malignancy, or nondiagnostic. Aspiration of a benign cystic lesion should result in collapse of the cavity. Documentation of complete collapse by follow-up ultrasonography may be helpful in decreasing the incidence of recurrence. Persistence of a palpable mass and recurrence following aspiration are general indications for further workup.

The use of FNA does confer a couple of advantages: it is inexpensive and quick to perform. The results can be made available rapidly, enabling a one-stop diagnostic and results clinic. Excellent results with FNA and triple assessment are reported in the literature. This approach has an accuracy of over 90% for palpable breast lesions when all 3 components are concordant for benign or malignant disease. However, in as many as 40% of cases, the findings are not concordant. [2]

Moreover, FNA is an operator-dependent technique, and the reporting of breast cytologic results is more demanding than histologic analysis. The degree of expertise required is not always available. Findings from cellular samples are limited in that the reviewer may not be able to determine the grade or invasiveness of the tumor. It is also difficult to diagnose lobular carcinoma on the basis of cytologic results [12] ; however, there is evidence to indicate that ultrasound and FNA biopsy are similarly useful for the axillary staging of patients with invasive lobular and invasive ductal carcinoma. [24]

The technique of FNA is determined largely by individual surgeon preference, which may, in part, reflect hand size and strength. It is typically used for identifying the presence of metastatid disease in abnormal lymph nodes. [14]  A 21-gauge (green) needle is used most commonly, although in expert hands, a 23-gauge (blue) needle can yield as much information, with less discomfort and bruising. Some clinicians opt for a hand-held 10-mL syringe, whereas others prefer a 20-mL syringe used with a syringe holder. Syringe holders allow a vacuum to be maintained easily but can make control of the needle tip less precise.

To perform FNA, the skin should be disinfected with an alcohol wipe, and the needle is passed through the lesion a number of times, while maintaining suction and steadying the breast tissue with the other hand. Appreciating the potential risk of pneumothorax is important when performing needle biopsies of the breast, and wherever possible, the needle should be angled tangentially to the chest wall. Continue sampling until aspirate is observed at the bottom of the plastic portion of the needle.

Transfer the aspirate to slides. Spread the aspirate thin enough to visualize individual cells. The slides may be air-dried or fixed according to the preference of the local laboratory. Cytospin preparations of the aspirate may allow a greater number of slides to be made.

A cytologist then examines the slide. The success of FNA biopsy is highly dependent on the expertise of the cytologist, as well as on accurate localization.

Core-needle biopsy

In view of the limitations with FNA, core-needle biopsy was developed. The core needles are of a larger caliber than the fine needles and are mounted onto a spring-loaded device that allows small cylinders of tissue to be cut and collected within the notch of the needle. Technically, the best core-biopsy samples are obtained by using 14-gauge needles. The optimal number of passes required vary according to the mammographic appearances of the lesions being sampled, with fewer passes required for solid lesions compared with microcalcifications. Several investigators have shown that a minimum of five to six passes is required when sampling microcalcifications to minimize sampling error. [25, 26, 27]  Specimen radiography is also required to ensure that representative calcifications are obtained (see image below).

Comparison of the size of specimens obtained durin Comparison of the size of specimens obtained during core biopsy with a 14-gauge needle (left) and those obtained during vacuum biopsy with a 16-gauge needle (right).

A few false-positive results are reported, and these are attributed to the removal of the lesion by means of core biopsy or a surgical failure to remove the lesion. The reported false-negative rate for malignancy with core biopsy is in the range of 2% to 6.7%, with a mean rate of 4.4%. [28, 29]  These false-negative results are more likely to occur with microcalcifications. In the United Kingdom's National Health Service (NHS) Breast Screening Programme, the actual false-negative rate is more variable. [7, 30]  This variation may represent the wide range of experience and expertise in the technique, as some units may still be moving from FNA to core biopsy.

Although the vast majority of the published literature on stereotactic core biopsy involves the use of dedicated, prone-table biopsy units, better results have been reported in United Kingdom centers that switch from FNA to core biopsy by using upright stereotactic devices. [31, 32]  With the advent of digital acquisition with upright stereotactic units, the accuracy could reasonably be expected to improve, and this improvement has certainly been the experience with early adopters of such systems (Evans AJ, personal communications, 2003).

The main advantage of core-needle biopsy is that it enables histologic diagnosis, which is vital to the planning of subsequent surgery and treatment of the patient. Stereotactic core-needle biopsy using a 14-gauge needle is widely accepted to be sensitive (90.5%) and specific (98.3%) in diagnosing breast masses, compared with 62.4% and 86.9%, respectively, for FNA. Core-needle biopsy can also be used to detect in situ as well as invasive malignancy. In addition, the status of estrogen receptors in the samples can easily be ascertained.

Certain histologic results should be interpreted with caution. With core biopsy, a propensity to underestimate certain pathology exists. [33]  Over 50% of all cases of atypical ductal hyperplasia (ADH) diagnosed with core biopsy prove malignant at surgery, and invasive carcinoma is found in up to 33% of core biopsy-confirmed ductal carcinoma in situ (DCIS). [16, 19, 20]

Radial scars diagnosed by means of core biopsy should also be regarded as high-risk lesions requiring excision. [29]  It is also more difficult to achieve a diagnosis using core biopsy in low-risk calcifications or where the underlying cause is subsequently proven to be benign. [34]  Therefore, core biopsy results should always be carefully analyzed to ensure that radiologic and pathologic concordance exists. One case report also raised concerns of malignant seeding of the needle track after core biopsy of a mucinous carcinoma [35] ; however, the significance and true incidence of this phenomenon remains uncertain

Wide-bore needle biopsy

A Tru-Cut needle, ideally 14-gauge, is used for core biopsy. Because of the fibrous nature of much breast tissue, adequate samples are best obtained using a spring-loaded firing device, such as the Biopty-Cut system. The procedure is often less painful than FNA despite the wider-bore needle.

After subcutaneous injection of local anesthetic, cores of tissue can be taken and should be fixed immediately in formalin. If the lesion contains calcification based on the mammogram findings, radiographs of the cores are taken to confirm the presence of calcification and that the cores are representative. The risk of bruising with wide-bore needle biopsies is higher than with FNA. For this reason, anticoagulants should be stopped, when possible, before biopsy and a pressure dressing is applied, usually for at least 24 hours.

Often, the samples are large enough to allow detailed histologic assessment, including tumor type and grade and hormone receptor status, but sampling error may occur if the cores are not representative of the entire lesion.

Vacuum-assisted core biopsy

With vacuum-assisted core biopsy devices (Mammotome; minimally invasive breast biopsy [MIBB]), an 11-gauge needle is positioned using ultrasonographic or mammographic guidance, and targeted breast tissue is drawn, cut, and saved in a collecting chamber. The procedure is performed under local anesthesia. These devices are relatively expensive, but they may be an alternative to open surgery for the therapeutic excision of benign lesions less than 15 mm or for additional tissue biopsy in patients with microcalcification or borderline breast lesions. 



Complication rates of Advanced Breast-Biopsy Instrumentation (ABBI) procedures requiring medical or surgical intervention are significantly higher than those of core biopsy and vacuum biopsy, with rates of approximately 1.1% for ABBI and less than 0.2% for core biopsy or vacuum biopsy. Although the complete removal of a small malignant lesion does occur, positive margin rates of 19%-100% have been described. [10, 36, 37, 38, 39, 40, 41, 42]  The cost has also been a subject of contention, as ABBI procedures are more expensive than any of the other percutaneous needle-biopsy techniques.


Cost-Effectiveness of Biopsy

Comparable health economic data on the comparative efficacy of image guidance modalities or needle-biopsy options may not be readily available. The costs of the consumables are not insubstantial compared with those of fine-needle aspiration (FNA).

Undoubtedly, percutaneous needle-biopsy techniques are advantageous in increasing the preoperative diagnostic accuracy of impalpable breast lesions and even in reducing the overall costs of diagnosis compared with surgical excision. [4, 5, 6, 10, 43, 44]  Even so, each new and incremental development has increased the cost of the procedure. It is therefore prudent to use a biopsy technique with full knowledge and awareness of the individual strengths and weaknesses of not only the individual modality, but also the expertise available in one's institution. According to available expertise, masses may be successfully sampled with FNA or core biopsy under ultrasonographic guidance, whereas stereotactic vacuum biopsy of small clusters of indeterminate microcalcifications may be more appropriate as a modality of choice compared with FNA or core biopsy. [14, 15]

An evidence-based approach to the image-guided modality and appropriate sampling modality for particular lesion types, combined with health economic measures is required. Due considerations must also be given to patient acceptance and outcome measures. A United Kingdom multicenter study evaluating the health economics and cost-effectiveness of 14-gauge core biopsies and biopsies using the Mammotome with conventional or digital upright stereotactic units and a prone table is underway.

The pathologic results should always be carefully evaluated in accordance to the level of clinical and radiologic suspicion in a multidisciplinary setting to ensure that the appropriate management decision is reached. Used in this manner, image-guided percutaneous needle biopsy can be used effectively to ensure that most palpable and impalpable breast lesions are diagnosed with accuracy and certainty.

The technique is safe and performed with the patient under local anesthesia. The complication rate is low, this method reduces intangible costs due to physical and psychologic morbidity.