The core biopsy--a minimally invasive procedure--is a common first-line approach to diagnose a breast mass, calcifications or enhancement (MRI). Occasional patients present with a palpable mass that is easily accessed with a Tru-cut type core biopsy apparatus. More commonly, core biopsies are performed to diagnose abnormalities found in the course of screening mammography & require image-guidance of some type because they are well below skin level & are otherwise not evident.

Core Biopsy Diagnosis--The Bottom Line: Core biopsies diagnosed as cancer, suspected cancer, atypical ductal hyperplasia, papilloma or other complex papillary lesion, or fibroepithelial neoplasm; cannot exclude phyllodes tumor mandate excisional biopsy or curative treatment, where the diagnosis is unambiguous. Patients with unequivocal carcinoma can have a full discussion of options before moving on to curative therapy, while those with fibroadenoma or non-atypical fibrocystic changes can safely forgo surgery and be followed. It is not worthwhile to “push too hard” to achieve a definitive diagnosis on a complex or ambiguous lesion or when the biopsy is too small for certainty; excisional biopsy can safely answer the clinical question in these circumstances.

Core biopsy of a palpable massEdit

The Tru-cut biopsy is done with an instrument equipped with an inner tissue sampling needle that fits inside an outer cutting needle in a spring-loaded gun that is used to advance the needle through the skin and subjacent breast. This is a one-shot biopsy, as the needle must be repositioned in the breast for each core. The tissue core(s) are placed in a formalin-filled specimen container & sent to Surgical Pathology where a Pathologist Assistant (PA) will gross the specimen.

Ultrasound-guided core biopsy of a mass or asymmetryEdit

Ultrasound guided core needle biopsy may be performed for sonographically visible masses whether or not the mass is palpable. Asymmetry is a variation on this theme--a density that the breast radiologist sees in one mammogram plane (e.g., craniocaudad), but not in the other (say, lateral). A biopsy needle is placed into the mass under real-time ultrasound guidance. Usually he biopsy needles range from 14- to 10-gauge & some are vacuum-assisted. In general, the radiologist extracts more samples if a smaller needle is used. For example, the typical specimen from a 14- gauge non-vacuum needle will consist of 6 cores. On the other hand, 1-2 cores are usually adequate to diagnose a mass-lesion using a vacuum-assisted 10-gauge needle. The cores are placed in a formalin-filled specimen container & sent to Surgical Pathology where a PA will gross the specimen. The procedure sonograms are archived in PACS, but there is no image of the specimen itself.

Stereotactic-guided core biopsy of calcificationsEdit

Calcifications are typically not visible using sonography; therefore they are biopsied using x-ray guidance. Breast radiologists usually perform stereotactic biopsies using a 9-gauge directional vacuum-suction biopsy instrument that makes it possible to remove multiple contiguous tissue cores with only a single placement. It consists of an outer needle or “probe” with a cylindrical tissue collection chamber cut into the shaft near the tip. After the probe is advanced into the lesion, a vacuum is applied to pull tissue into the collection chamber. Then a hollow cutting bore rotating at high speed is inserted & removes a core of tissue that is collected in a chamber. The radiologist rotates the probe clockwise and more samples are pulled into the collection chamber. At the end of the biopsy procedure, the tissue samples are emptied from the collection chamber into a divided saline-containing Petri dish and x-rayed. The specimen radiograph is stored in PACS.

Although the Petri dish compartments are labeled as 12:00, 3:00, etc, these designations have no significance; the purpose of the dish is to spread out the cores to facilitate specimen radiography. The radiologist compares the patient’s mammogram to the specimen radiograph in order to confirm that the targeted calcifications have been sampled, circling the calcifications of interest on the digital specimen radiograph in PACS as a guide for the pathologist. The Petri dish is then sent to Surgical Pathology, where a PA will quickly gross process the specimen in formalin.

Stereotactic-guided core biopsy of a mass or asymmetryEdit

Some very small masses (< 1.0 cm) located deep in the breast may be biopsied using a stereotactic approach. The process is identical to that used when calcifications are the target, although fewer cores are typically obtained and go into a single formalin-containing specimen container; gross processing is the same as for an ultrasound-guided core biopsy of a mass. There is no specimen radiograph.

MRI-guided core biopsy of localized enhancementEdit

Unlike mammography, magnetic resonance imaging (MRI) is not used for screening of the general population. We see breast MRI used in 2 contexts: 1) to screen high-risk patients, e.g., BRCA-1 or -2-mutation carriers; and 2) to look for multi-centric unilateral or bilateral cancer in patients with biopsy-proved carcinoma in one breast. Enhancing lesions show increased and/or abnormally-patterned blood flow. Enhancement on MRI is a very nonspecific attribute; most enhancing lesions in the breast are benign.

The Suros instrumentation system is commonly used to sample the enhancing region under MRI guidance. The procedure images are archived in PACS; there is no specimen radiograph of these core biopsy specimens. The number of tissue cores ranges from 10 to 40; these are placed in a formalin-filled specimen container & sent to Surgical Pathology where a PA will gross the specimen.

Fresh Handling/Grossing InEdit

Note the number of cores, diameter (generally the same for each) and lengths. If there are < 5 cores, it is reasonable to specify the length of each. Stereotactic core biopsies for calcifications are often > 20 cores & specifying the length of each is neither illuminating nor practical. In this case, give a range of lengths. The character & consistency of these specimens is rather undistinguished. Most consist of irregularly white & yellow breast tissue; alternatively, some are simply yellow fat and others consist only of white tissue.

Placing no more than 3 tissue cores in any cassette makes it easier for the histotechnologist to embed the cores in a flat, non-overlapping fashion. In most cases, histological sections cut at 3 different levels are sufficient for diagnosis; additional sections can be made as needed.

Sample DictationEdit

Sample Dictation 1, ultrasound-guided core biopsy of a massEdit

Received in formalin are 3 cores of irregularly white & yellow breast tissue, each 0.2 cm in diameter, with lengths of 0.5, 0.9 and 1.2 cm, respectively. In toto in one cassette: 1A.

Sample Dictation 2, MRI-guided core biopsy of a focal enhancementEdit

Received in formalin are 9 cores of irregularly white & yellow breast tissue, each 0.2 cm in diameter, with lengths ranging from 0.5 to 1.3 cm, respectively. In toto in three cassettes: 1A, 1B & 1C.

Sample Dictation 3, stereotactic core biopsy of calcificationsEdit

Received in saline in a divided Petri dish is a specimen consisting of multiple cores of irregularly yellow & white breast tissue in labeled compartments as follows:

12:00: Four cores, each 0.2 cm in diameter and ranging in length from 0.5 to 1.0 cm. In toto in 1A.

3:00: Three cores, each 0.2 cm in diameter and ranging in length from 0.5 to 1.2 cm. In toto in 1B.

6:00: Five cores, each 0.2 cm in diameter and ranging in length from 0.5 to 1.0 cm. In toto in two cassettes: 1C and 1D.

9:00: Eight cores, each 0.2 cm in diameter and ranging in length from 0.5 to 1.2 cm. In toto in three cassettes: 1E, 1F and 1G.

Center: Three cores, each 0.2 cm in diameter and ranging in length from 0.5 to 1.2 cm. In toto in 1H.

Review and SignoutEdit

The basic principles of review & signout are the same for all types of breast core biopsies. You should know/do the following:

  • To avoid mix-ups, do not put more than one case into a slide folder;
  • For every case, make sure that the name & accession number on the requisition matches those on the slides – if you find discordance, STOP & consult with Chris Mignona, Lyn Thomas, and/or the attending;
  • Make sure the laterality (right or left) is clearly specified & there are no discordances with what is written in other sections of the requisition – if you find discordance, STOP & consult with the attending;
  • Know the clinical problem: Mass, asymmetry, calcifications, enhancement, etc.;
  • Know the image-assisted approach: ultrasound, MRI, stereotactic;
  • For masses or asymmetries, know the size of what you are looking for – this may require looking up the breast radiology reports;
  • For core biopsies for calcifications, use the gross dictation to label the slides 12:00, 3:00, etc so that it is easy to match the slides with the specimen x-ray;
  • For calcifications, you & the attending must examine the specimen radiograph in order to compare the size, pattern and distribution of calcifications in the tissue slides with what is circled on the specimen radiograph, so that you can make a specific correlative statement in the final report.

The Diagnostic Report for a Core BiopsyEdit

Different pathologists may prefer one format over another; feel free to ask them why they do it a certain way. Formatting should make it easy for the clinician to quickly grasp the key information; a linear narrative often works best. The lead-in to the diagnosis should mention laterality, any additional localizing information that is provided on the requisition, the clinical problem that prompted the biopsy, and the image modality that guided the biopsy.

Sample Heading 1:

Right breast mass at 1:00, ultrasound-guided core biopsy:

Sample Heading 2:

Left breast, upper outer quadrant calcifications, stereotactic core biopsy:

Sample Heading 3:

Right breast, enhancement at 12:00, MRI-guided core biopsy:

Sample Diagnoses:

Benign breast tissue with proliferative fibrocystic changes without atypia and associated microcalcifications, see note.
NOTE: The microcalicficiations correlate with the radiologic findings on the specimen radiograph.
Fibroepithelial lesion (or) Fibroadenoma.
Lobular carcinoma in situ (or) Invasive lobular carcinoma.
Ductal carcinoma in situ, (solid and/or cribiform) pattern(s), with (comedo-type necrosis and/or associated microcalcifications).
Invasive ductal carcinoma, (low/intermediate/high nuclear grade or well/moderately/poorly differentiated) with associated ductal carcinoma in situ, (solid and/or cribiform) pattern(s) with (comedo-type necrosis and/or microcalcifications).

Modified Bloom-Richardson gradingEdit

Differentiation is evaluated by mBR grading (tubules + nuclei + mitoses). If there is not enough material to grade architecture and mitoses, you can just give the nuclear grade.

Evaluate entire tumor for percentage of tubule formation (structures with clearly defined central lumina surrounded by polarized epithelial cells) > 75%: score of 1 10–75%: score of 2 < 10%: score of 3

Access nuclear pleomorphism based on worst area:

Minimal no significant size ↑; uniform chromatin score of 1
Moderate variable size and shape; open chromatin; nucleoli score of 2
Marked marked variation in size and shape ± bizarre nuclei; prominent nucleoli score of 3

Assign mitotic score (1–3) by assessing most active/peripheral area of tumor for unequivocal mitotic figures per high-power field; at least 10 fields should be counted; score cutoffs depend on microscope field diameter (FD):

FD (mm) Score 1 Score 2 Score 3
0.40 ≤4 5–8 ≥9
0.44 ≤5 6–10 ≥11
0.50 ≤6 7–13 ≥14
0.55 ≤8 9–16 ≥17
0.60 ≤9 10–19 ≥20
0.65 ≤11 12–23 ≥24
0.70 ≤13 14–27 ≥28

Add up scores to arrive at final grade:

3–5 points: Grade I

6–7 points: Grade II

8–9 points: Grade III


A diagnosis for any core biopsy done for calcifications should have a NOTE.

Example 1 Left breast, upper outer quadrant calcifications, stereotactic core biopsy: Intraductal carcinoma with calcified comedo-type necrosis; see note.

Comment (aka NOTE): Calcifications in intraductal carcinoma correlate with those annotated on the specimen radiograph.

Example 2 Right breast calcifications at 10 – 11:00, stereotactic core biopsy: Proliferative fibrocystic changes consisting of florid duct hyperplasia, usual type, sclerosing adenosis and cysts; see note.

Comment (aka NOTE): Calcifications in cysts & sclerosing adenosis correlate with those annotated on the specimen radiograph.

Example 3 (Curve-ball) Left breast, upper outer quadrant calcifications, stereotactic core biopsy: Intraductal carcinoma with calcified comedo-type necrosis; see note.

Comment (aka NOTE): Calcifications in cysts correlate with those annotated on the specimen radiograph; there are no calcifications in the intraductal carcinoma.

Frequently Asked Questions about Core Biopsies 1. In the case of a core biopsy for calcifications, what should I do if there are no circles on any of the specimen images?

Check the report and see if the radiologist indicates that the biopsy did, in fact, show calcifications on the specimen radiograph. Occasionally, the biopsy procedure will fail. If “yes,” then email the radiologist(s) a courteous request, asking them to go into PACS, circle the calcs of interest on the specimen radiograph, and email you & your attending when this is done.

Don’t guess about calcifications! Because calcifications are in all breast tissue, their mere identification in a biopsy is clinically meaningless. The pattern and distribution of calcifications in the tissue cores must match those that the radiologist tells us are abnormal.

2. What should I do if I don’t see calcifications in the tissue core sections that correspond to those circled on the specimen radiograph?

First of all, realize that two types of calcium deposit occur commonly in abnormal patterns in the breast: Calcium pyrophosphate deposits, which are dark purple on H & E-stained sections; and calcium oxalate, which are optically clear crystals that are strongly refractile when examined with plane-polarized light and typically reside in apocrine cysts. If you don’t see either type of calcium deposit, point this out to your attending at signout. The next step will probably be a trip over to Breast Imaging for paraffin block x-ray.

3. In the case of a core biopsy for a mass, what if I don’t see an obvious mass-forming process like a cancer or a fibroadenoma?

Again, check the report to see if the radiologist successfully skewered the abnormality. Occasionally, the target will turn out to be a cyst that collapses when punctured; then, the lack of a mass-forming process is not concerning. Some procedures are aborted because of inability to get into the lesion or patient discomfort. Otherwise, it is important to note that you do not see an obvious discrete mass-forming process represented in the biopsy, because this may signify sampling error. This discordance will mostly likely lead to an open biopsy.

5. Should I be looking for calcifications in core biopsies done to diagnose a mass or an MRI-detected lesion?

No, no, no!!! A search for calcifications in these contexts is not clinically illuminating. Non-pathologic calcifications are in all breast tissue. Mentioning incidental calcifications in the report of a core biopsy performed to diagnose a mass or enhancing lesion may convey the impression that the pathologist is not grasping the clinical problem.

6. In the case of carcinoma, should I order predictive marker stains on the core biopsy?

Yes, these small, well-fixed specimens are ideal for immunohistochemical stains. If the diagnosis is invasive ductal or invasive lobular carcinoma, order the panel of ER, PR and HER-2/neu. For intraductal carcinoma, just order the ER/PR panel. Choose the block with the most carcinoma.

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