The capability of diagnosing a breast lesion percutaneously has dramatically improved the management of breast abnormalities over the last two decades. Prior to the development of these techniques, surgical excision was the procedure performed to identify the etiology of a nonpalpable mammographically detected lesion. The majority of these lesions, now classified as BIRADS 4—suspicious for malignancy—actually are benign. Until percutaneous breast biopsy was developed, many women underwent surgery for benign abnormalities to diagnose them.
Initially, fine needle aspiration biopsy (FNAB) was performed with mammographic (1) or sonographic guidance. The limitation of FNAB is the limited sampling and the need for an experienced cytopathologist for interpretation. Bolmgren (1) described the use of a stereotactic table that allowed for precise placement of a needle into a small lesion in the breast. Using this technology, percutaneous breast biopsy began its evolution. Core-needle biopsy techniques evolved as biopsy guns with Tru-cut-type automated needles of varying caliber were designed. Initially, 18-gauge core needles were used, followed by 16-gauge and subsequently 14-gauge automated core needles. The automated 14-gauge core needle is still used for the biopsy of masses, particularly with ultrasound guidance. Early results of core biopsy using a 14-gauge automated needle showed a sensitivity for malignancy of 85% (2) and a concordance between the pathologic results of core biopsy and surgery ranging from 87% to 96% (2,3,4,5). Parker et al. (3), in 1990, described biopsy utilizing stereotactic guidance in 103 patients, using a biopsy gun and automated cutting needles ranging from 18- to 14-gauge. The use of the 14-gauge needle improved the sample size and the results at pathology and, with this improvement, the management of breast abnormalities changed considerably.
Prior to the advent of the larger needles, a limited number of lesions were biopsied percutaneously—particularly cancers, complicated cysts, and fibroadenomas. However, many lesions, particularly fibrocystic lesions that were manifested as microcalcifications, yielded very nonspecific results on cytology and therefore were better diagnosed by surgical excision. With the development of percutaneous tissue sampling techniques, many more lesions could be biopsied by core biopsy instead of surgery.
The biopsy of microcalcifications has been challenging using core needles, because the volume of tissue removed is important to the accuracy of diagnosis for proliferative lesions. Vacuum-assisted breast biopsy probes have evolved to answer this problem, and larger samples can be obtained quickly and accurately using these devices. With the advent of vacuum-assisted biopsy, the speed of tissue acquisition, the volume of tissue acquired, and the accuracy for certain types of lesions have improved. Liberman et al. (6) showed that for calcifications that are highly suggestive of malignancy, the use of stereotactic 11-gauge vacuum-assisted biopsy was significantly more likely than the 14-gauge core needle or 14-gauge vacuum-assisted probe to spare a surgical procedure and was associated with the highest cost savings.
The advantages of percutaneous needle biopsy are many and include:
Using percutaneous breast biopsy, benign lesions can be diagnosed accurately and do not require surgical excision in most cases.
Lesions that are suspicious for carcinoma can be proven to be cancer preoperatively. This is important in planning the proper surgery for the patient. Instead of performing a surgical excision for diagnosis, a lumpectomy with sentinel node biopsy can be performed with knowledge of the diagnosis. In particular, the diagnosis of invasive breast cancer on core biopsy allows for definitive therapy and increases the possibility of a single surgery. King et al. (7) reported that 90% of patients with invasive carcinoma on core biopsy could have a single surgery for definitive therapy. Liberman et al. (8) found that a single surgery was performed in 84% of women for whom the diagnosis of cancer was made on
core biopsy, in comparison with 29% of women in whom the diagnosis was made by surgical biopsy. Jackman et al. (9) found that a single surgery was performed in 90% of patients whose cancers were found on percutaneous biopsy, versus 24% of patients whose cancers were diagnosed surgically.
For multiple suspicious lesions, percutaneous biopsy is a very important tool to define the extent of disease. The presence of multiple cancers in one breast that involve more than one quadrant indicates multicentric disease (Fig. 16.1). This condition usually requires mastectomy for treatment. Therefore, the patient may be assessed by imaging and percutaneous biopsy, and be managed with definitive therapy—all without the need for unnecessary preliminary excisions. Rosenblatt et al. (10) found that multisite stereotactic biopsy had a positive effect on patient care in 80% of patients by helping to confirm the need for mastectomy or by documenting benign disease at multiple sites and avoiding unnecessary surgery.
Figure 16.1 HISTORY: 74-year-old woman with a palpable thickening in the left periareolar area, for second opinion after being told that she had multiple “cysts.”
MAMMOGRAPHY: Left MLO (A) and CC (B) views show multiple small masses in the left breast. The palpable thickening corresponded to a small indistinct mass at 4 o'clock, seen also on spot compression (C) (arrows). An indistinct mass is also noted in the upper inner quadrant (arrowheads), appearing spiculated on spot compression (D). Multiple other small round masses are present, primarily in the lower outer quadrant. Ultrasound demonstrated 10 small solid masses, including those seen on spot compression. Biopsy of five of these lesions was performed. Sonographic images of the palpable mass (E) and three other biopsied masses (F, G, H) are shown.
HISTOPATHOLOGY: Invasive ductal carcinoma, all sites. The patient underwent mastectomy for multicentric disease.
NOTE: Percutaneous biopsy is an ideal method to assess extent of disease in a patient with multicentric carcinoma.
Percutaneous biopsy is a less costly way of diagnosing a breast lesion than is surgery. Lee et al. (11) found an average cost savings of stereotactic biopsy versus open biopsy of $741 per case. The greatest savings occurred with indeterminate masses. Lindfors (12), in a study of the costeffectiveness of core biopsy found that the marginal cost per year of life saved by screening mammography was reduced a maximum of 23% (from $20,770 to $15,934) with the use of core biopsy instead of surgical biopsy. Liberman et al. (13) found that stereotactic biopsy decreased the cost of a breast lesion diagnosis by over 50%. Lind et al. (14) found that stereotactic core biopsy shortened the time from detection at mammography to diagnosis and breast-conserving therapy, permitted discussion with the patient of treatment options, reduced the positive margin rate and re-excision rate, and represented a cost savings in the management of nonpalpable breast cancer.
Ultrasound guidance is excellent for needle biopsy procedures in the breast. Cyst aspiration, fine-needle aspiration biopsy, and core biopsy can be performed readily for lesions that are visible sonographically. The benefits of ultrasound guidance include the ease of patient positioning, speed of the procedure, real-time visualization of the needle trajectory, low cost, lack of use of ionizing radiation, and the use of nondedicated equipment (15). Gordon et al. (16) found a sensitivity of 95% in 213 malignant lesions biopsied using ultrasound guidance and fine needle aspiration with a 20-gauge needle. Parker et al. (17) found that ultrasound-guided core biopsy using a free-hand technique with a long-throw 14-gauge core needle was a highly accurate alternative to open biopsy for the diagnosis of breast masses. Vacuum-assisted biopsy is
also performed with ultrasound guidance (18) and offers a rapid and accurate method to biopsy lesions.
Figure 16.2 Schematic for ultrasound-guided cyst aspiration shows that the needle is placed vertically, directly toward the mass. The needle tip is visible when it bisects the scan plane at the level of the lesion.
Figure 16.3 Schematic of a long-axis or horizontal approach that is used for core-needle biopsy with ultrasound guidance. The lesion is visualized in the center of the long axis of the transducer field, and the dermatotomy is made lateral to the edge of the transducer. This allows the needle to be placed horizontally, parallel to the chest wall, for a safer sampling when the needle is fired.
For cyst aspiration or fine-needle aspiration biopsy, a small-gauge hypodermic needle is used. The needle may be connected with thin, short tubing to a 20 cc syringe, allowing the interventionalist to handle the needle with more control. For cysts, a 1-inch long, 21- to 25-gauge needle is used. For fine-needle aspiration biopsy, the smaller the needle, the better the sample, so a 25-gauge hypodermic needle is optimal. A vertical approach, as described by Fornage (19), may be used for needle placement for cyst aspiration or FNAB (Fig. 16.2). In this manner, the needle is placed the shortest distance from and directly into the mass. For this placement, the needle is placed at the midline of the long face of the transducer, and the needle is visualized once it is at the depth of the lesion. If a long axis or horizontal approach is used, the needle is placed at the short end of the transducer and is visualized in its entirety as it is advanced toward the lesion. The horizontal approach usually requires a longer needle to reach the lesion (Fig. 16.3).
For core-needle biopsy or vacuum-aspirated biopsy, a horizontal/oblique approach must be used. Because of the forward firing of the needle, it is imperative that an approach parallel to the pectoralis major muscle be used for safety (Fig. 16.4). Many of the core needles typically used for ultrasound-guided biopsy advance into the breast about 2 cm on firing. An angled approach could easily allow the needle to penetrate the chest wall. For core biopsy, the area is cleansed with antiseptic solution, and a sterile technique is used. The device is visualized in the scan plan. It can be very helpful to have the assistant hold the transducer so that the interventionalist can use both hands to control the needle and skin and to hold the biopsy gun. Lidocaine 1% is injected for local anesthesia, and a small dermatotomy is made. The location of the dermatotomy depends on the depth of the lesion. The deeper the lesion, the farther from the edge of the transducer is the dermatotomy made. If the dermatotomy is too close to
the edge of the transducer, the needle insertion will not be parallel to the chest wall.
Figure 16.4 Ultrasound-guided core biopsy being performed with an automated core needle using a long-axis (horizontal) approach. The patient is turned to allow access to the lateral aspect of the breast and to allow room for the biopsy apparatus.
Figure 16.5 HISTORY: A 29-year-old with a new palpable right breast mass.
MAMMOGRAPHY: Sonography (A) demonstrates the lesion to be hypoechoic, slightly lobulated, and well-defined with no acoustic shadowing. All the features suggest that this is most likely a fibroadenoma. Vacuum-assisted biopsy was performed with ultrasound guidance. Pre-fire (B) and post-fire (C) sonographic images show that the needle has traversed the lesion. One pass was made.
HISTOPATHOLOGY: Fibroadenoma (concordant with imaging findings).
Once the needle has been placed proximal to the lesion (pre-fire position), the patient is prepared for the first sample by reminding her that she will hear a loud sound. The gun is fired and the needle traverses the lesion (post-fire position) (Fig. 16.5). Vacuum-assisted probes (VAB) may also be used for ultrasound-guided biopsy (Fig. 16.6). Using VAB, the needle may be inserted through the lesion rather than fired, and then multiple samples are acquired utilizing suction. A clip may be placed under ultrasound guidance and is particularly important for very small lesions that may no longer be clearly evident on ultrasound after the biopsy. Some of the vacuum-assisted probes are designed for clip insertion through the probe. Also, clips loaded into a stiff introducer-type needle are excellent for direct clip placement following needle biopsy.
Ultrasound guided biopsy is an ideal method for the percutaneous biopsy of women with implants. The implant wall can be visualized as the procedure is performed. In the
case of patients with implants, it is imperative that care be used in administering the local anesthesia and in the dermatotomy so that the implant is not punctured. The horizontal approach must be used for needle placement and tissue sampling. Automated core needles, rather than vacuum-assisted probes, are better suited for patients with very thin breast tissue over the implant (Fig. 16.7).
The advent of stereotaxis has greatly impacted the ease of accurate needle placement into small nonpalpable lesions and has allowed for a nonsurgical approach. Stereotactically guided needle biopsy can be performed for nodules as small as 3 mm. Stereotaxis can also be used for needle localizations and is particularly advantageous for the localization of a lesion seen clearly on only one view and superimposed over dense tissue on the orthogonal view. Stereotactic guidance with vacuum-assisted needles has become the standard or typical way of diagnosing suspicious microcalcifications.
Core biopsy can be performed with stereotactic, sonographic, or magnetic resonance imaging (MRI) guidance. Stereotactic biopsy units can be prone tables on which the breast is dependant through an aperture in the table, or upright units (20) that attach to the mammography equipment. When the patient is biopsied using an upright unit, she may sit up if the lesion is located in the superior aspect of the breast. However, if the lesion can be biopsied via a medial, lateral, or inferior approach, the patient lies on a stretcher in a decubitus position for the procedure (Fig. 16.8) (21,22).
The advantages of the upright unit are the ease in positioning the patient, the access to the posterior aspect of the breast, the comfort of the patient in not having to lie prone, the ability to use the room for general mammography as well as biopsy, and the interaction of the biopsy team with the patient. Advantages of the prone table unit are the access to the inferior aspect of the breast, the lack of patient visibility of the procedure, and the rarity of a vasovagal reaction.
The principle of stereotaxis is based on the movement of the x-ray tube relative to the breast at angles of a fixed degree of obliquity that allow for the precise calculation of the lesion location. The technique described here is based on the Siemen's Opdima stereotactic unit (Siemens Medical Solutions, Malvern, PA), but various stereotactic units are designed around similar basic principles and procedures. The breast is compressed and is not moved during the entire procedure. Two 15-degree oblique spot views of the lesion are made (stereotactic pair). The radiologist identifies the lesion on each image and confirms the reference point on the images. The reference point is a fixed point in the image receptor plate that is visible on the images. Based on the position of the lesion target point versus the reference point, the X, Y, and Z coordinates of the lesion are calculated by the computer. The length of needle to be used must be chosen and entered into the computer.
At the stereotactic unit, the needle is then zeroed, thereby moving the needle guides into position at a ΔX = 0, ΔY = 0, and ΔZ = 0. This position indicates that the needle tip is over the lesion on the X and Y axes and that, when the gun is fired, the target point of the lesion will be at the level of the center of the needle's trough on the Z axis.
Following local anesthesia and a dermatotomy. the needle is placed through the guides. Repeat spot oblique views (a stereotactic pair) are made to confirm accurate needle placement. The needle position must be carefully analyzed on these pre-fire images, and these should show the needle tip at the leading edge of the lesion on both images (Fig. 16.9). If the needle is off position on the X, Y. or Z axis, its position must be adjusted based on the pre-fire images. If the needle is repositioned to any degree, a repeat stereotactic pair should be obtained. Examples of X, Y, Z, and complex errors are show in Figures 16.10, Figures 16.11, Figures 16.12, 16.13, and methods to correct the errors are described.
Once the needle position is accurate, the sampling begins. With a vacuum-assisted probe or an automated core needle, the gun is fired. The needle is fired within the breast a distance specific for each particular needle and gun; most needles advance about 2 cm into the breast. Therefore, the thickness of the breast must be sufficient to accommodate this throw or stroke of the needle. Sampling begins by retrieving tissue cores at every 2 o'clock position with a vacuum-assisted probe. Typically two rotations are made, yielding 12 core samples. This circumferential sampling pattern is rapid and accurate.
If an automated core needle is used instead, the needle is oriented in position at ΔX, ΔY, and ΔZ at 0.0 mm. The gun is fired, and the first sample is retrieved by withdrawing the needle. The needle is replaced into the breast, and similar samples are obtained at ΔX at +2 or 3 mm, ΔX at -2 to 3 mm, ΔY at +2 to 3 mm, and ΔY at -2 to 3 mm (Fig. 16.14).
For the biopsy of calcifications, specimen radiography is performed to verify that the lesion has been correctly sampled (Fig. 16.15). This step is not necessary for noncalcified lesions. The vacuum probe is withdrawn 5 mm, and a clip is placed through the probe and deployed into the middle of the biopsy site. This change in the ΔZ of 5 mm is made because the clip tends to deploy forward at the end of the trough and will lie deep to the lesion once the compression is released. A final stereotactic pair is obtained to confirm that the clip has deployed, and the needle is withdrawn from the breast. Compression is applied to achieve hemostasis, the wound is cleansed, and Steri-Strips are applied to close the dermatotomy. An ice pack is placed over the breast for 20 to 30 minutes, and the wound is assessed for hemostasis before the patient is discharged.
Figure 16.6 HISTORY: A 52-year-old woman with a history of benign cyst aspirations, who presents with a palpable mass in the left breast for biopsy.
MAMMOGRAPHY: Left ML (A) and MLO spot (B) views show a round isodense mass with indistinct margins in the superior aspect of the breast. Pre-fire image from the ultrasound (C) showed the mass to be complex, with a thick rind. Core-needle biopsy with vacuum-assistance was performed. The pre-fire image (C) shows the needle tip (arrow) at the proximal edge of the lesion. The post-fire image (D) shows that the needle has traversed the middle of the lesion (arrow). With the first pass, the fluid component was aspirated along with the tissue sample.
The second pre-fire image (E) shows that the remaining mass is smaller and solid in appearance, and the needle tip is in position(arrow). The post-fire image (F) shows the horizontal position of the needle, parallel to the chest wall, and the needle tip through the mass. A clip was placed into the mass. Post-procedure ML (G) and CC (H) views show the clip within the residual mass.
HISTOPATHOLOGY: Poorly differentiated invasive ductal carcinoma with papillary features.
For aspiration procedures using stereotactic guidance, a coaxial system can be used to avoid multiple needle punctures. A 19- or 20-gauge outer cannula can be placed at the proximal edge of the lesion, and 22-gauge needles are passed through the cannula for aspiration.
Stereotactically guided fine-needle aspiration is of help for small well-defined masses that are new in comparison with prior examinations and that are not seen or are not definitely identified as cystic on ultrasound (Fig. 16.16). Fluid can be aspirated from these cysts under stereotactic guidance. Either pneumocystography or
follow-up mediolateral and craniocaudal views should be performed to confirm the disappearance of the nodule.
Fine-Needle Aspiration Biopsy
FNABs for palpable breast masses have been performed with success in lieu of open biopsy (23,24). For a questionably palpable lesion that cannot be satisfactorily aspirated by palpation only, or for a nonpalpable lesion, fine-needle aspiration can be performed under stereotactic or sonographic guidance. The following criteria are critical for fine-needle aspiration of nonpalpable lesions to be of value: (a) extremely accurate needle placement, (b) good techniques of aspiration and preparation of the smear, (c) experienced cytolopathologists
for interpretation of the sample, and (d) accurate and consistent results for cytologic determination of benign and malignant lesions (25). The experience of the person performing the aspiration is reflected in the percentage of aspirates that have sufficient material for analysis (23,26).
Figure 16.7 HISTORY: A 53-year-old woman with a history of breast implants who presents with an irregular mass identified on mammography in the right breast at 3 o'clock.
MAMMOGRAPHY: Right breast ultrasound (A) shows an irregular hypoechoic mass with angulated margins and some surrounding edema. The sonographic features are highly suggestive of malignancy. The breast parenchyma is very thin in this area. The pectoralis major muscle (arrow) is visualized, as well as the anterior edge of the subpectoral implant (arrowhead).
Core-needle biopsy using an automated 14-gauge needle was performed. It is imperative that the needle be placed carefully and horizontally, keeping the needle and its trajectory parallel to the pectoralis major muscle and the chest wall. Pre-fire image (B) shows a proper needle position (arrow) proximal to the mass. Post-fire position (C) shows that the mass has been transversed (arrow) by the needle. Three core samples were obtained.
HISTOPATHOLOGY: Invasive ductal carcinoma.
Regardless of the mode of FNAB guidance, a 22- to 25-gauge needle is placed into the lesion, suction is applied, and the needle is moved back and forth within the lesion. The suction is released, the needle is withdrawn, and the aspirate is ejected from the needle onto the slides and is smeared and fixed. Multiple passes will increase the yield of cells for cytologic analysis. When mammographic guidance with a fenestrated plate was used for FNAB of nonpalpable breast lesions, Helvie et al. (27) found that only 46% of the aspirates
of 215 lesions contained representative material. If an aspirate of a suspicious mammographic lesion is negative, core biopsy or open biopsy is necessary for accurate diagnosis.
Figure 16.8 Patient is in position for stereotactic breast biopsy using an upright unit and a vacuum-assisted probe (Mammotome, Ethicon Endo-Surgery, Cincinnati OH). When the lesion is located in the upper aspect of the breast, a superior approach is used. For a lateral, medial, or inferior approach, the patient is placed in a decubitus position.
Figure 16.9 A, B: Accurate pre-fire needle position. The needle tip is at the leading edge of the lesion on both stereotactic images. The images must be analyzed together to understand where the needle tip is relative to the target point and where the needle tip will likely be once the gun is fired. The orientation of the X, Y, and Z axes are shown. C, D: Accurate post-fire needle position: After the gun has been fired, the needle has moved forward through the lesion, and the needle tip is traversing the target point on both images.
Figure 16.10 A, B: Y-axis error: The needle tip is above the target point on both images. If it is fired in this position, the lesion will be missed. This is the typical Y-axis error on the upright unit, because the patient has pulled back a bit and the lesion has moved back. The targeted point, therefore, lies anterior to the lesion on the stereotactic images. To correct this error, the ΔY is moved back (on the upright unit) or down (on the prone table). C, D: Y-axis error: The needle tip is below the target point on both views. This is the typical Y-axis error on the prone table, because the patient has pulled up a bit, moving the lesion above the needle tip. To correct this problem, the ΔY is moved up (on the prone table) or forward (on the upright unit).
Fine needle association biopsy under stereotactic guidance has been an option for the evaluation of nonpalpable solid lesions (28,29,30,31,32,33,34,35,36,37,38). Variable results from studies comparing cytology and histology for nonpalpable lesions have demonstrated a relatively high sensitivity and specificity for this procedure. For FNAB to be of value and to be cost effective, it is necessary that lesions called “malignant” be malignant and that no false positives occur. Otherwise, histologic confirmation would be necessary prior to definitive treatment. Because of the small size of these lesions, the mixed nature of the aspirate (38), the necessity for highly accurate needle placement, and the technique for aspiration, the numbers of “insufficient for cytologic analysis” specimens during FNAB have ranged from 0% (31) to 36% (33), with most series reporting on insufficient sampling in approximately 20% of cases. In a review of 270 lesions that were biopsied using fine-needle aspiration techniques with either sonographic or stereotactic guidance, Ciatto et al. (39) found that the sensitivity was 88.5%, specificity was 94.6%, and inadequacy rate was 3.7% for malignant lesions and 22.9% for benign lesions when stereotactic
guidance was used. With sonography, the results were 96% sensitivity, 98.4% specificity, and 0% insufficient sampling for cancers, and 28.4% insufficient sampling for benign lesions. Stereotactic systems have allowed for improved sampling in comparison with the standard mammographic localization grid system (38).
Figure 16.11 A, B: X-axis errors: The needle tip lies to the right of the lesion on both views. Although the needle appears to traverse the lesion on the A image, it is located far to the right of the lesion on the B view. If the needle is fired in this position, it will miss the lesion. To correct this problem the needle should be shifted to the left on the ΔX axis. C, D: X-axis error: The needle tip lies to the left of the lesion on both stereotactic images (an X-axis error). To correct this position, the ΔX is shifted to the right.
The greatest advantage of FNAB is in the elimination of some open biopsies, but for this advantage to be present, it is critical that the radiologist and cytologist be highly experienced in the procedure. If any false-positive diagnoses should occur, then histologic confirmation prior to definitive therapy for “malignant” lesions would be necessary. Certainly, FNAB has a definite role in the evaluation of some benign lesions. Small equivocal masses that are cysts can be aspirated with a high degree of accuracy and need not be subjected to open biopsy. Similarly, an option for lesions that are of low suspicion on mammography, such as “probable fibroadenomas,” can be confirmed with cytologic analysis and followed mammographically rather than being resected.
Cysts that are simple on ultrasound do not need to be aspirated unless they are markedly symptomatic (Fig. 16.16). A simple cyst is one that is anechoic, well-defined, with a thin wall and acoustic enhancement.
Complicated cysts are those that may contain low-level echoes or lack enhancement (Fig. 16.17). These are typically aspirated when solitary, new, larger, or when associated with other lesions suspicious for malignancy in the same breast. Sometimes multiple simple cysts and complex cysts having a similar appearance are followed at a short interval rather than aspirating all that are not completely clear.
Figure 16.12 A, B: Z-axis error: In these images, the needle has traversed the image and is past the target point on both images. This indicates that the tip is deep to the lesion. This occurs in the following circumstances: (a) the gun has not been cocked, and the needle is inserted in the fired position, (b) the wrong needle length has been programmed into the unit, or (c) the ΔZ is not set to 0, but is set inferior to the target point. It can be very dangerous to fire the needle at this point. The needle can penetrate the opposite surface of the breast and hit the image receptor, breaking or bending it. C, D: Z-axis error: In these images, the needle is short of the target point on both images, indicating that the tip is shallow to where it should be. This problem occurs when the needle length has been incorrectly programmed into the computer, or when the ΔZ is set above the 0.00 mm.
Cyst aspiration can be performed in various ways depending on how the mass is identified. A large palpable cyst may be aspirated by palpation alone. Cysts that are symptomatic and under pressure may be aspirated to relieve the symptoms, and this may be performed by palpation or with ultrasound guidance (Fig. 16.18). Ultrasound offers the ability to visualize the cyst and to verify that it is drained. Most often, cysts are aspirated using ultrasound guidance, which is how they are initially characterized. Either a short-axis approach (vertical) or a long-axis approach (horizontal) can be used, depending on the operator's skills and preferences. Particularly with the vertical approach, a 25-gauge hypodermic needle attached to a 20-cc syringe by a short piece of flexible tubing is ideal. A 1-inch needle is adequate in most cases unless the breast is very thick,
and the short needle length is safe and easy to handle. If the fluid is very thick, a larger gauge needle (21- or 22-guage) may be necessary. The smaller bore needles are easily visible on ultrasound.
Figure 16.13 A, B: Complex errors: X and Y errors. X- and Y-axis error in which the needle tip lies to the right of and above the lesion. This is corrected by shifting the ΔX toward the left and the ΔY down or toward the chest wall (depending on the prone versus upright unit). C, D: X- and Y-axis errors in which the needle tip is to the right and below the lesion. This is corrected by shifting ΔX to the left and ΔY forward or up depending on the type of unit. E, F: X- and Y-axis error in which the needle tip is to the left and below (behind) the lesion. The correction is to shift the ΔX to the right and the ΔY up or forward prior to firing the gun. G, H: X- and Y-axis error in which the needle tip is to the left and above the lesion. The correction is to move the ΔX to the right and the ΔY down or back.
Once the cyst is punctured and drained, a quick assessment of fluid type is needed before terminating the procedure. If the fluid appears bloody or very turbid, slides should be prepared and sent for cytologic analysis. In this situation, it is important to be able to identify the lesion later. in the event that atypia requiring excision is identified. Therefore, leaving a small amount of residual fluid is helpful. If the cyst completely collapsed and is no longer visible, placing a clip into the area may be helpful in the future, if excision is needed.
When cyst fluid is clear, straw-colored, or green, it is benign fluid and can be discarded. If the fluid is bloody or turbid, it should be sent for cytologic analysis. Usual cytologic findings that are benign and require no further evaluation are apocrine metaplasia, foamy macrophages, acellular fluid, and amorphous debris. Because the breast is a modified sweat gland, the epithelium is secretory or apocrine in nature.
The evaluation of a patient with a well-defined breast mass on mammography may include ultrasonography, needle aspiration, and occasionally pneumocystography. Pneumocystography can be performed if breast ultrasound is not available, if the sonographic findings are equivocal, or if the lesion is very small and not visible
on ultrasound. Some studies (40) have shown a therapeutic value from breast cyst puncture and pneumocystography. Using pneumocystography, or air injection into the cyst cavity, an intracystic tumor can be identified. The incidence of intracystic carcinoma ranges from 0.2% (41) to 1.3% (42). Tabar et al. (40) identified 13 benign and 13 malignant tumors on a series of 434 pneumocystograms. The fluid aspirated from five to 13 cancers was not bloody, as is generally thought to be indicative of malignancy, and cytology performed in 11 of the cases was negative in eight (40). In a 1-year follow-up of 130 simple cysts diagnosed at pneumocystography, 88% did not refill after initial puncture, and 97% were definitively treated with pneumocystography after a repeat puncture. The presence of air within the cyst cavity may induce collapse and sclerosis of the wall (43).
Pneumocystography is a simple technique to perform and produces minimal discomfort to the patient. The aspiration of the cyst can be performed by palpating it, under ultrasound guidance (44), or under mammographic or stereotactic guidance. Palpable and nonpalpable cysts can be aspirated easily under mammographic guidance because the lesion can be fixed for puncture by compressing the breast. This technique is described as follows.
On viewing the initial mammogram, one determines the shortest distance from the lesion to the skin surface—medial, superior, or lateral. The localization compression plate is placed over the breast at the determined location, and an image is made. The patient remains in position with the breast compressed while the image is reviewed; the coordinates of the lesion are determined. A 20- to 22-gauge
needle attached to a syringe is placed into the breast at this point and is slowly withdrawn while mild suction on the syringe is applied. When liquid is aspirated, the needle is held in place until aspiration is complete; the syringe is removed and replaced with a syringe containing a volume of room air, slightly less than the volume of fluid aspirated, and the air is injected into the cyst cavity (Fig. 16.19). If the fluid aspirated is bloody, it is sent for cytologic examination.
Figure 16.14 HISTORY: A 72-year-old woman for biopsy of a spiculated mass.
MAMMOGRAPHY: Preliminary left CC (A) and magnification CC spot (B) views show a small spiculated mass at the posterior edge of the parenchyma (arrow) laterally. A stereotactic pair (C) for targeting obtained with the aperture over the superior aspect of the breast shows the spiculated mass (arrow) on both images. The pre-fire set of stereotactic images (D) with the automated core needle in place shows the needle tip to lie just proximal to the center of the lesion on both images, which is a proper pre-fire position. Five core samples were obtained.
HISTOPATHOLOGY: Invasive ductal carcinoma.
Figure 16.15 HISTORY: A 60-year-old woman with an abnormal screening mammogram, for additional evaluation.
MAMMOGRAPHY: Right magnification ML (A) and CC (B) views show scattered fibroglandular densities and clustered fine pleomorphic microcalcifications at 10 o'clock (arrows) that are suspicious for malignancy. Stereotactically guided vacuum-assisted biopsy was performed using an 11-gauge needle. Stereotactic pair (C) shows the microcalcifications (arrow) within the aperture, as well as the reference point in the unit (arrowhead). After targeting the lesion, the needle has been positioned at ΔX = 0, ΔY = 0, and ΔZ = 0. In this position, the needle tip is at the leading edge of the abnormality on both views (D).
Following sampling, the specimen radiograph (E) shows the calcifications to be included in the first cores. A clip was placed and a post-clip stereotactic image (F) shows that the calcifications have been removed, and the clip has been deployed. Post-clip mammography ML (G) and CC (H) views show the clip to be in accurate position (arrows) and that many of the calcifications have been removed. A small air pocket is present at the biopsy site.
HISTOPATHOLOGY: Ductal carcinoma in situ.
Figure 16.16 HISTORY: A 64-year-old G3, P2 woman with a positive family history of breast cancer, for screening.
MAMMOGRAPHY: Right MLO (A) and craniocaudal (B) preliminary stereotactic pair (C and D), stereotactic pair with needle placement (E and F) from a stereotactically guided aspiration, and post-aspiration MLO (G) and craniocaudal (H) views. A relatively well-circumscribed 9-mm isodense mass nodule (A and B) is present in the right lower outer quadrant (arrow). This nodule had developed since the previous study 3 years earlier. Ultrasound was performed and showed a small nodule to contain some internal echoes.
Stereotactically guided aspiration was performed to confirm that the new mammographic lesion was actually the small complicated cyst. Preliminary stereotactic pair (C and D) demonstrates the mass in the field and a dot marking the center (arrow) for targeting the coordinates of the lesion. Stereotactic pair views with the needle in place (E and F) show the needle within the nodule. Aspiration yielded 0.2 mL of clear fluid.
Post-aspiration images MLO (G) and CC (H) demonstrate complete resolution of the nodule.
IMPRESSION: Simple cyst confirmed by stereotactically guided aspiration.
In mediolateral and craniocaudal projections, films are made immediately after injection of air. The walls of the cyst cavity should be thin and smooth (Fig. 16.20). Any intraluminal filling defect or focal irregularity of the wall is regarded with suspicion for an intracystic tumor. Benign intracystic papillomas and papillary carcinomas can be visualized in this way. If an intracystic abnormality is identified, excision of the lesion is indicated.
Figure 16.17 HISTORY: A 58-year-old woman with a history of complex cysts, for aspiration.
MAMMOGRAPHY: Right complicated cyst is seen on sonography, showing well-defined margins and low-level internal echoes. FNA was performed using a vertical approach and a 25-gauge needle. Post-aspiration image shows the cyst to have collapsed, and the needle tip is visible (arrow). Cloudy fluid was aspirated and sent for cytology.
CYTOLOGY: Scant amorphous debris.
Figure 16.18 A symptomatic cyst is aspirated with ultrasound guidance, using a short-axis (vertical) approach. The needle tip is seen within the center of the cyst initially (A). Clear fluid was aspirated, and the post-aspiration image (B) shows that the cyst has partially collapsed.
Core-needle biopsy can be performed using stereotactic, sonographic, or MRI guidance. Core-needle biopsy has evolved from the use of 18-gauge automated cutting needles to vacuum-assisted biopsy probes ranging from 14- to 8-gauge. With this evolution came the possibility of accurately diagnosing more types of mammographic abnormalities. One disadvantage of FNAB is the large number of nonspecific diagnoses, particularly for many benign lesions.
With core-needle biopsy, specific histologies are obtainable from masses, focal asymmetries, and microcalcifications.
Figure 16.19 For pneumocystography under mammographic guidance, the needle is placed into the breast overlying the lesion to be aspirated (A). The needle is slowly withdrawn into the lesion while aspiration is being performed (B) and, after aspiration is complete, air is injected (C).
Figure 16.20 Left CC view from a pneumocystogram that was performed with mammographic guidance. The cyst has been drained and filled with air, showing a smooth, normal internal wall without filling defects.
The size of the lesion no longer limits the ability to use core-needle biopsy, as it did initially. Mainero et al. (45) found no significant relationship between lesion size and the ability to establish a specific diagnosis. In early series (46,47,48,49), before clips were available to mark the biopsy site, lesions less than 5 mm in size were not ideally biopsied percutaneously, since the entire mammographic lesion could be removed with the core needle. If the patient needed a subsequent excision, locating the original biopsy site was challenging and inaccurate. With the ability to deploy a clip, the biopsy of smaller lesions is feasible.
Figure 16.21 A: Automated core-needle and biopsy gun (Bard, CR Bard, Inc., Covington, GA). The 14-gauge needle is placed in the spring-loaded gun. B: The trough of the needle when open.
The diagnostic accuracy of a lesion biopsied using a core-needle technique is improved with an increase in the number of samples as well as increased experience in performing the procedure (50). Brenner et al. (50) found that more than 80% of the lesions (except for clustered microcalcifications) were diagnosed on the basis of two core samples; with five core samples, the accuracy was 98% for masses and 91% for calcifications (50). Liberman et al. (47) found that five cores taken with a 14-gauge automated needle yielded a diagnosis in 99% of masses but only 87% of calcifications.
Literature on the accuracy of needle biopsy has shown that the 14-gauge needle is superior to smaller needles for accuracy of diagnosis (51,52). The concept of the core needle is that it has an inner needle with a trough that pierces the tissue when the gun is fired. Instantaneously, the outer cutting cannula moves forward over the needle, transecting tissue that is contained in the trough. An example of the Bard (CR Bard, Cincinnati, OH) automated core needle is shown in Figure 16.21.
Another type of cutting needle, the Cassi (Sanarus Medical Inc., Pleasanton, CA), utilizes a freeze-stick concept (Fig. 16.22). The sharp inner stylet is advanced into the lesion, a quick freeze around the needle using CO2 is
applied to the hold the lesion, and the outer cutting cannula fires forward, severing the tissue around the stylet.
Figure 16.22 Freeze-stick device for breast biopsy (Cassi, Sanarus Medical, Inc., Pleasanton, CA). The tip is inserted under ultrasound guidance (A). CO2 is expelled to freeze the tissue immediately around the needle, and the outer cannula fires forward (B).
Vacuum-assisted probes were developed in the mid 1990s, the first being the Mammotome (Ethicon Endo-Surgery, Cincinnati, OH) (Fig. 16.23). This directional, vacuum-assisted device is fired into position so that its trough is in the middle of the lesion. The vacuum is then applied to pull the tissue into the trough of the needle and to transport it back up into the probe. The tissue is retrieved from a specimen chamber external to the breast; therefore, the probe stays in the breast while multiple samples are acquired. The probe is rotated circumferentially as samples are acquired, thereby optimizing the volume of tissue acquired and the accuracy of the procedure. These probes range from 14 to 8 gauge in diameter.
Figure 16.23 Vacuum-assisted biopsy probe (Mammotome, Ethicon Endo-Surgery, Cincinnati, OH. The open trough has small perforations within it that are used for applying suction and for draining fluid.
In comparison with the automated 14-gauge core needles, the individual core specimen weights are much greater with the Mammotome. Burbank (53) reported mean specimen weights of 96 mg from the 11-gauge Mammotome probe versus 40 mg from the
14-gauge probe. Berg et al. (54) found the mean weights to be 17.7 mg from the automated 14-gauge core needle, 36.8 mg from the 14-gauge directional vacuum-assisted probe, and 94.4 mg from the 11-gauge Mammotome probe.
Figure 16.24 Vacuum-assisted, hand-held device (Vacora, CR Bard, Covington, GA). The 10-gauge needle is loaded in a gun that has a 30-cc syringe that provides suction for one sample (A). The needle is withdrawn, the sample collected, and the needle repositioned for additional samples. The open trough of the needle, which has a scalpel tip, is shown in B.
Since the Mammotome was developed, several other vacuum-assisted probes are available. A vacuum-assisted probe that allows for only individual sampling is the Vacora (CR Bard, Inc., Covington, GA) (Fig. 16.24). This 10-gauge probe has a scalpel tip and is loaded into a gun that contains a 30-cc syringe that provides suction. One specimen is acquired, and the needle is removed from the breast; the specimen is retrieved and the needle must be repositioned for additional sampling. This type of needle is compatible with a coaxial cannula that facilitates repositioning the needle in the breast. The Vacora can be used with stereotactic or sonographic guidance.
Other directional, multisample probes are the EnCor (SenoRx Inc., Aliso Viejo, CA) and Suros (Suros Surgical Systems, Inc., Indianapolis, IN) types. In both cases, the system is closed, so that the individual specimens are not retrieved manually from the collection chamber, as they are with the Mammotome. Instead, the vacuum pulls the specimen back into a closed collection chamber that is dismounted from the unit at the termination of the procedure (Fig. 16.25).
A clip is placed at the biopsy site to mark the area for future reference. If the lesion requires subsequent surgical excision, the clip marks the site for the needle localization. This is particularly important for small lesions, in which the entire mammographic abnormality may be removed by the core needle. A clip at a site of residual calcifications is also helpful on subsequent mammography to verify that the area had already been biopsied. In the case of larger cancers that might be treated first with neoadjuvant chemotherapy to reduce their size prior to surgery, the placement of a clip may be very important to document the location of the tumor (55). At times, the regression of the tumor is so great after the administration of the chemotherapy that the mass is no longer visible on mammography or ultrasound.
Clips may be deployed through vacuum-assisted probes, or they may be placed independently via an introducer. It is important to have a clear understanding of how the clip deploys so that it will be placed in an accurate position. With some types of clips that are inserted through the vacuum-assisted probes under stereotactic guidance, the probe must be withdrawn slightly so that the clip deploys in the middle of the biopsy cavity.
Clips do not necessarily deploy accurately, even though all the proper steps are followed. Rosen et al. (56) reported that 28% of clips were more than 1 cm from the target on at least one post-biopsy image. The migration of clips has occurred uncommonly, as documented on short- and long-term follow-up mammography (57,58,59). For these reasons, it is imperative that a post-procedure mammogram be obtained to verify the location of the clip relative to the biopsy site. This relationship should be described in the report. If any subsequent procedures are needed, the localization can be performed more accurately.
Figure 16.25 A vacuum-assisted system for ultrasound or stereotactic breast biopsy (A) (EnCor, SenoRx, Aliso Viejo, CA) has a closed system for specimen retrieval (B).
Complications of Core Biopsy
Major complications of core-needle biopsy of the breast are rare. Infection can occur uncommonly and is managed with antibiotics. A clinically important hematoma has been described in less than 1% of patients in several series (46,60,61). The development of a large post-biopsy hematoma can present a clinical problem if the lesion is malignant and its visibility is obliterated by the fluid collection. This can result in a potential delay in surgery until the hematoma resorbs (62), if no clip has been placed to indicate the biopsy site.
An unusual complication of core biopsy is a milk fistula. This connection between the skin and the milk duct can occur if biopsy is performed in a lactating patient. Because of this, FNAB is performed first to attempt diagnosis in a lactating patient (63), and core biopsy is avoided.
Tumor cells can be displaced during core-needle biopsy. Actual seeding of the needle tract has only been reported once (64). Harter et al. (64) reported a case of seeding of the needle tract with mucinous carcinoma cells that were identified 2 weeks after a core biopsy performed with a 14-gauge core needle. Given the vast number of core biopsies that have been performed since then, this risk of seeding is exceedingly low.
A more commonly observed finding, however, is known as epithelial displacement, which can occur during core biopsy of the breast. Youngson et al. (65) described the presence of displaced epithelial fragments in the fibrous breast tissue or fat, adjacent to or within the tract of a core-needle biopsy. These epithelial fragments can mimic foci of invasion, but importantly, they are associated with the traumatic needle effect and, in these cases, no other true invasion is found elsewhere in the specimen. Epithelial cell displacement has been observed in benign lesions as well as malignancy, particularly in papillary ductal hyperplasia and papilloma (66). The viability of such displaced cells is not known.
Diaz et al. (67) studied of 352 cancer excisions in patients who had undergone core biopsy for diagnosis. The authors found that tumor cell displacement occurred in 32% of patients, and the incidence and amount of tumor cell displacement was inversely related to the interval between core biopsy and excision. Tumor cell displacement was observed in 37% of specimens previously biopsied with an automated gun versus 23% of specimens obtained via a vacuum-assisted needle. Tumor cell displacement was seen in 42% of patients who underwent excision in less than 15 days from the core biopsy, compared with only 15% of patients who underwent surgery more than 28 days from biopsy. This relation suggested than the displaced cells do not survive (67).
The performance of a successful core-needle biopsy is usually straightforward. The management of the results, however, can be challenging. A clear understanding before the procedure of what the anticipated results may be is extremely helpful when the pathology report arrives. This necessitates that a careful review of the imaging study is performed to characterize the lesion and to anticipate the
outcome. The procedure is far from complete with the dictation of a report describing the procedure. The procedure is complete once the pathology report has been reviewed, correlated with the mammographic findings, the management recommendation is determined, and the patient and referring physician have been notified. The radiologist determines if the radiologic and pathologic findings are concordant and if surgical excision or re-biopsy are necessary (48,68).
Providing the pathologist with clinical information, the radiologic impression and whether calcifications are present is very helpful. The presence of calcifications should prompt the pathologist to search specifically for calcium to identify the area of interest within the various cores.
Calcification retrieval is imperative when the biopsy is performed for microcalcifications. Specimen radiography is performed during the procedure to confirm that calcifications have been removed (69). The 14-gauge Mammotome has been shown (70) to be superior to the 14-gauge automated needle in the ability to obtain calcifications on the specimen radiography (100% versus 91% respectively). Jackman et al. (71) reported calcification retrieval in 94% of 14-gauge automated core biopsies, 99% of 14-gauge directional vacuum-assisted biopsies, and >99% of 11-gauge vacuum-assisted biopsies. Liberman et al. (72) reported failure to remove calcifications in 5% of lesions; the lack of calcifications on specimen films was more likely in lesions <5 mm in size, for amorphous calcifications, and in cases where the probe was fired outside the breast (72).
If calcifications are not present on the specimen radiography, a review of the stereotactic images should be made to determine if the needle position is accurate. A repeat stereotactic pair may be helpful as well. Additional sampling is needed to try to obtain the calcifications.
If calcifications are present on specimen radiography, the case is completed and the tissue is sent to the laboratory. The pathologist must search the slides for calcifications to assure that the region of interest is included in his review. If no calcifications are identified initially, polarized light is used to try to identify calcium oxalate crystals, because calcium oxalate is not readily identifiable on hematoxylin and eosin staining. If no calcium is identified at this point, the tissue block is releveled, and more slides are prepared and stained. If, after the block is exhausted, no additional levels can be made, and no calcium is identified, the management of the case falls back to the radiologist and depends on the specimen radiography. When specimen radiography clearly shows the calcifications, and the review of the post-procedure mammogram shows that calcifications have been removed, the patient may be followed with mammography at 6 months. The lack of visualization of the calcium by the pathologist may have been the result of two problems: The microtome used for sectioning the tissue block can hit a large calcification and pop it out of the tissue, or the calcification can float out of the tissue when it is stored in the formalin for an extended period prior to sectioning (73). An algorithm for the management of calcifications is shown in Figure 16.26.
When percutaneous biopsy yields a diagnosis of a high-risk lesion, surgical excision is performed. The presence of atypical ductal hyperplasia (ADH) should lead to surgical excision of the lesion (Fig. 16.27). Some controversy has arisen about lobular carcinoma in situ (LCIS), atypical lobular hyperplasia (ALH) radial scar, papillary lesions, and atypical columnar cell lesions, but most radiologists recommend excision of these. One of the reasons to excise a high-risk lesion is that the core biopsy may underestimate the disease, and therefore, excision of the remainder of the lesion may yield carcinoma. The other reason is to excise higher-risk tissue that has a greater potential to become malignant.
ADH is a proliferative lesion in the duct that has an appearance very similar to low grade ductal carcinoma in situ (DCIS). The distinction between ADH and DCIS may be determined in some cases by the number of ducts involved. A few ducts may be called ADH, but a more extensive lesion may be called DCIS. Therefore, in the cases of microcalcifications that are actually low-grade DCIS, acquiring a larger volume of tissue samples is important for a proper diagnosis. Underestimation rates for ADH vary with the type of needle used, ranging from 15% to 50% (74,75,76,77,78,79,80,81). With directional vacuum-assisted biopsy, the underestimation rate of ADH is less than it is with an automated core needle (74).
In a review of multiple series, Reynolds (75) found that of 630 ADH lesions, 37% were malignant on excision. Findings on excision were DCIS (76%) and invasive ductal carcinoma (24%). The automated 14-gauge core-needle biopsies were associated with an underestimation rate of 41% on average, whereas the vacuum-assisted 14- and 11-gauge probes are associated with cancer in 15% of cases. Jackman (76) reported an underestimation rate for ADH with automated core biopsy of 58%. Darling et al. (77) found the underestimation rate for ADH to be less with the 11-gauge vacuum probe than with the 14-gauge probe. Jackman et al. (78) reported an underestimation rate of DCIS to be 1.5 times more frequent when 10 or fewer specimens were obtained, than when more than 10 were taken.
When DCIS is found at stereotactic core-needle biopsy, approximately 20% to 25% of cases yield invasive carcinoma at surgical excision (82,83,84). Brem et al. (85) showed that the accuracy of diagnosis of invasive breast cancer was greater in lesions <30 mm. In lesions 30 mm or larger, the underestimation rate for DCIS was 43%. Like ADH, the 11-gauge probe improved the underestimation rate for DCIS, but 15% of the cases of DCIS were found by Won et al. (83) to be invasive at surgery.
Figure 16.26 HISTORY: A 48-year-old woman recalled from screening for right breast microcalcifications.
MAMMOGRAPHY: Right magnification ML view (A) shows clustered amorphous microcalcifications in the inferior aspect of the breast(arrow). Stereotactic biopsy was performed with vacuum-assistance and 12 samples were acquired. Specimen radiography (B) showed the microcalcifications within the cores. Pathology showed atypical ductal hyperplasia and, because of this high-risk result, excision was recommended. Right ML (C) and CC (D) views from the needle localization show that the hookwire is in position at the clip placed during the biopsy procedure.
HISTOPATHOLOGY: Ductal carcinoma in situ, (initially called ADH on core biopsy).
Although the management of ALH or LCIS on percutaneous biopsy has been somewhat debatable, in a review of 35 patients with lobular neoplasia (LCIS or ALH), 17% were upgraded to DCIS or invasive cancer at excision (86). Based on this, the authors recommended surgical excision.
Radial scar is a proliferative lesion that may include ductal hyperplasia, atypical hyperplasia, or even DCIS. The rate of carcinoma found at radial-scar excision has been reported to range from 0% to 40% (68). The risk of malignancy has been shown to be highest when the radial scar is associated with atypia.
Asymptomatic papillary lesions identified on core biopsy are also controversial (87,88,89). When atypia is present within a papilloma, the risk of malignancy is higher, and surgical excision is performed. Several series support the follow-up of patients with a core biopsy diagnosis of papilloma without atypia (89,90). A relationship also may
exist between sclerotic papillomas or micropapillomas and increased likelihood of malignancy on excision (89).
Figure 16.27 Management of specimen from biopsy of calcifications.
Columnar cell lesions include a wide variety of pathologic lesions characterized by columnar cells that line the terminal duct lobular unit. These etiologies range from columnar cell alternation of the lobules to DCIS with columnar cell features (68). When columnar cell change is associated with atypia, the management of this diagnosis on core biopsy is similar to that of atypical ductal hyperplasia—namely, excision (68).
Most often a fibroadenoma is clearly defined as such on core biopsy, and no further management is necessary.
However, at times, a fibroadenoma can have a very cellular stroma that may raise the question or possibility of a phyllodes tumor. If this question is raised by the pathologist, excision of the entire lesion is performed.
Figure 16.28 HISTORY: A 49-year-old for routine screening mammogram.
MAMMOGRAPHY: Left MLO (A) views show a small spiculated mass (arrow) in the left upper outer quadrant, highly suspicious for malignancy. The lesion was identified on ultrasound (B) (arrow). Core biopsy was performed using an automated core 14-gauge needle (C), showing the needle in position (arrow). Pathology from the core biopsy showed fibrocystic change. Because the pathologic finding is not concordant with the mammographic finding, re-biopsy or excision was recommended.
HISTOPATHOLOGY: Invasive ductal carcinoma (initially benign on core biopsy and nonconcordant).
An assessment for concordance determines if the lesion has been adequately sampled and diagnosed correctly. With FNAB, the negative cytologic aspiration in the face of a suspicious palpable mass prompts further tissue sampling, because the results are nonconcordant and the false-negative rate of FNAB is not insignificant. Percutaneous core biopsy has a greater degree of accuracy than FNAB, but it is not 100% accurate. Therefore, if the lesion is a BIRADS 5 mass or area of calcifications, for example, and the result is benign, one must consider carefully whether to follow the patient. Sclerosing adenosis can produce a small spiculated lesion that can be a concordant pathology. However, a spiculated mass that is called, for example, fibroadenoma or fibrocystic change, is not concordant (Fig. 16.28). Also, sufficiency of sampling must be considered. A dense mass should not yield “fat with scattered stromal elements” as the pathologic results.
The radiologist should also not hesitate to call the pathologist to discuss any concerns about the case. The anticipated malignant diagnosis that is not confirmed on the pathology report might prompt a conversation with the pathologist and a re-look at the slides prior to a re-biopsy. Sometimes additional leveling will reveal the lesion.
The correlation of the radiologic and pathologic findings is one of the key components of a successful percutaneous breast program. A careful selection of the type of procedure and skill in performing it contribute to the successful diagnosis of nonpalpable breast lesions.