eMedicine Specialties > Radiology > Breast

Breast, Stereotactic Core Biopsy/Fine Needle Aspiration

Author: Hemant Singhal, MD, MBBS, FRCSE, FRCS(C), Senior Lecturer, Department of Surgery, Imperial College School of Medicine, UK; Consultant Surgeon, Northwick Park and St Marks Hospitals, UK
Coauthor(s): William Teh, MB, ChB, FRCR, Clinical Director, Department of Radiology, Northwick Park Hospital, UK
Contributor Information and Disclosures

Updated: Apr 22, 2008

Introduction

The establishment of national breast-screening programs in Europe and North America has 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.

For excellent patient education resources, visit eMedicine's Women's Health Center and Procedures Center. Also, see eMedicine's patient education articles Breast Lumps and Pain, Mammogram, and Lumpectomy.

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Breast Cancer, Mammography

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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

There are several advantages in definitively diagnosing these lesions with needle biopsy. 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

Indications for Stereotactic Biopsy

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.^8,9

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.

Techniques and Principles of Stereotaxis

Earlier techniques in stereotaxis used mammographic projections to localize the target lesion within the breast. The principles of localization involve mapping the distance between the geometric center of the breast with the target lesion in 2 different planes and then projecting the coordinates onto the patient's breast (see Image 1).

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 1).^10,11,12,13 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.

Types of Stereotactic Breast Needle Biopsy

Fine needle aspiration biopsy

The earliest stereotactic biopsies were performed by using fine needles (eg, spinal needles, hypodermic needles), which yield cellular samples. The sample is then smeared onto a slide, which is then fixed and stained. A cytologist then examines the slide. The success of fine needle aspiration (FNA) biopsy is highly dependent on the expertise of the cytologist, as well as on accurate localization.

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 1-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 results⁸ ; 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.¹⁴

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 5-6 passes is required when sampling microcalcifications to minimize sampling error.^15,16,17 Specimen radiography is also required to ensure that representative calcifications are obtained (see Image 2).

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 2-6.7%, with a mean rate of 4.4%.^18,19 These false-negative results are more likely to occur with microcalcifications. In the United Kingdom's NHS Breast Screening Programme, the actual false-negative rate is more variable.^7,20 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.^21,22 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. 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).^23,24,25

Radial scars diagnosed by means of core biopsy should also be regarded as high-risk lesions requiring excision.¹⁹ 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.²⁶ 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 carcinoma²⁷ ; however, the significance and true incidence of this phenomenon remains uncertain.

Vacuum-assisted biopsy and Advanced Breast-Biopsy Instrumentation

Although core biopsy 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 2 main types are (1) vacuum-assisted biopsy devices, such as the Mammotome device (Ethicon Endo-Surgery, Inc, Cincinnati, Ohio) and the Minimally Invasive Breast Biopsy (MIBB) device (US Surgical, Norwalk, Conn), and (2) image-guided single-cylinder excision alternatives, such as the Advanced Breast-Biopsy Instrumentation (ABBI; US Surgical). 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.

Although both 14- and 11-gauge needles, or probes, were initially available, only the 11-gauge probe is now widely used. The device can be used under sonographic guidance or stereotactic guidance; the patient is prone or upright with the use of certain units, with adequate room to accommodate the device.

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 DCIS found to be invasive carcinoma at surgery compared with 21% with 14-gauge core biopsy.^24,28  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.²⁹ Although vacuum biopsy appears to be nearly 3 times more accurate than core biopsy in the diagnosis of ADH, underestimation still occurs in 18-25% of cases.^23,25

Because vacuum biopsy removes more tissue during sampling than core biopsy, complete removal of the mammographic abnormality has been reported^28,30 ; however, this is not always correlated with removal of the pathologic lesion at surgery.²⁴ 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.³¹  The likelihood of this occurrence is probably minimized if the operator chooses to insert the probe into position rather than fire it into place.

The ABBI system similarly uses a vacuum-assisted coupling to harvest breast tissue. This system was developed with both diagnostic and therapeutic applications. The ABBI device is more invasive, with a diameter of 5-20 mm, and it is restricted to prone-table systems only. It utilizes the insertion of a localizing T-wire. A single, whole cylinder of tissue is removed after transection with an electrocautery snare.

Because the volume of tissue removed is larger and complete, this method offers the theoretical advantages of an increase in diagnostic accuracy due to sample size and the potential to assess the excision margins of an incidentally removed malignant tumor to determine its complete removal. However, the failure rate of ABBI procedures appears to be high. Rates of up to 31.5% have been reported.^{12,32,33,34,35,36}  These failures appear to be due to a whole host of reasons, including poor patient selection, technical problems with the T-bar, and failure to remove the tissue.

Complication rates of 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^{12,33,35,36,37,38,39,40}  The cost has also been a subject of contention, as ABBI procedures are more expensive than any of the other percutaneous needle-biopsy techniques.

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Cost-effectiveness of Biopsy

There are not many readily comparable health economic data on the comparative efficacy of image guidance modalities or needle-biopsy options. The costs of the consumables are not insubstantial compared with those of 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.^{4,5,6,12,41,42} 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 sonographic 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.

Clearly, 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.

Summary

Stereotactic needle biopsy is an essential tool in the diagnosis of nonpalpable or indistinct breast lesions. More sophisticated stereotactic techniques with real-time MRI guidance are emerging. Earlier and smaller breast lesions are being detected, mainly during breast screening when some of these cancers are amenable to minimally invasive treatment. Hence, stereotactic localization will play an increasingly prominent role in both the diagnosis and therapy of breast lesions.

Related eMedicine topics:
Breast Cancer
Breast Cancer Evaluation
Breast Cancer, Mammography

Related Medscape topics:
Resource Center Breast Cancer
Specialty Centers Pathology & Lab Medicine
CME Ductal Carcinoma in Situ: Evolving Strategies to Optimal Diagnosis and Management
CME Local-Regional Therapy for Breast Cancer
CME/CE Treatment Options for Early-Stage Breast Cancer: Information for Primary Care Providers

Multimedia

(Enlarge Image)

Media file 1: Stereotactic images obtained during a prone-table biopsy procedure.

(Enlarge Image)

Media file 2: 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).

Keywords

SCB, FNA, CB, core needle biopsy, stereotactic needle biopsy, breast biopsy, breast screening, vacuum-assisted biopsy, fine-needle aspiration biopsy, Minimally Invasive Breast Biopsy, MIBB, Advanced Breast-Biopsy Instrumentation, ABBI, Mammotome

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