The Breast Cancer Pathology Report and Biopsy: Section 6.a.
CONTENTS:
6.1 The Breast Cancer Pathology Report
6.2 Tissue Sampling and Examination
6.2.1 Fine Needle Aspiration (FNA) Cytology
6.2.2 Core Needle Biopsy (CNB)
6.2.3 Excision Biopsy
6.2.4 Frozen Section
6.2.5 Lymph Node Sampling
6.3 Light Microscopy and Diagnostic Histopathology
6.3.1 Reporting FNA Cytology
6.3.2 Reporting Core Needle Biopsies (CNB)
6.3.3 Lympho-vascular Invasion (VI)
6.3.4 Micro-vessel Density (MVD)
6.3.5 Reporting Excision Specimens.
6.3.6 Reporting Lymph Node Specimens
Forward to section 6B on immunohistochemistry. Back to 5D on rare types of cancer in the breast
All About the Tests for the Breast Cancer Pathology Report
This section will include the ‘specialized’ diagnostic tests that may be done on breast tissue samples when examined by the Pathologist. When a patient receives a copy of the diagnostic breast cancer pathology report, there may be references to ‘special stains’ ‘tumor markers’ or ‘IHC’ or ‘molecular tests.’
These most commonly used tests include immunohistochemistry (IHC) for cell biomarkers, estrogen-receptor (ER), progesterone-receptor (PR) and HER2 testing.
At the end of this section, there is a list of key references to the published literature, with links to access the articles. There are also some helpful links to patient websites and to sources of further information.
6.1 The Breast Cancer Pathology Report
A written breast cancer pathology report follows a biopsy or surgical procedure. The completed and ‘authorized’ breast cancer pathology report will contain the diagnosis of any abnormality detected by the Pathologist following examination of the cells or tissue down a (light) microscope.
The Pathologist will send a breast cancer pathology report to the patient’s physician within seven days after the biopsy or surgery is performed.
Who is the Pathologist?
The Pathologist is a medically trained doctor who has chosen diagnostic Pathology as their specialty. In the U.S., the name Surgical Pathologist or Anatomic Pathologist will be used. In other parts of the world, ‘Histopathologist’ and ‘Cytopathologist’ are names given to these diagnostic doctors.
More about the Breast Cancer Pathology Report
The breast cancer pathology report includes patient information, a description of the cells and tissues examined, a description of the findings of any ‘special’ tests or ‘special stains’ and the diagnosis. In difficult cases, or rare conditions, a ‘differential diagnosis’ will be given, with a recommendation for further tests on the cells and tissue.
The breast cancer pathology report usually begins with a ‘gross’ or ‘macroscopic’ description of the tissue sample (size, weight, focal or diffuse abnormality, measurements including excision margins).
The breast cancer pathology report includes the following information:
- Patient information: name, date of birth, biopsy date
- Gross description: color, weight, and size of tissue as seen by the naked eye
- Microscopic description: how the sample looks under a microscope and how it compares with normal cells
- Diagnosis: type of tumor and grade (how abnormal the cells look under a microscope and how quickly the tumor is likely to grow and spread)
- Tumor size: measured in centimeters
- Tumor margins: there are three possible findings when the biopsy sample is the entire tumor: (1) ‘Positive margins‘ mean that cancer cells are found at the edge of the material removed; (2) ‘Negative margins,’ ‘not involved,’ ‘clear,’ or ‘free margins’ mean that no cancer cells are found at the outer edge; (3) ‘Close margins‘ are neither negative nor positive.
- Other information: usually information about samples sent for ‘special stains’ or other tests or a second opinion.
- Pathologist’s signature and name and address of the laboratory
Figure 6.1 The Pathologist and the Pathology Report.
A. The Pathologist receives the breast tissue and describes the ‘gross’ appearance
and ensures that the tissue is fixed. B. Fixed and processed tissue is sectioned
by the Lab Technician who cuts 3 to 6 micron thin sections on to glass slides
and stains the sections. C. The Pathologist looks at the breast tissue sections
on the glass slide using light microscopy.
6.2 Tissue Sampling and Examination
Breast tissue removed during a biopsy procedure is sent to the Pathology Laboratory. Unless the sample is a cytology (cell) sample or a core needle biopsy (CNB), the breast tissue is received and described by the Pathologist who selects small pieces for further examination.
The small tissue samples are processed in fixatives or preservatives that include formalin, embedded in paraffin wax, sliced very thinly, mounted on glass slides. The thin tissue sections are stained with histochemical cell dyes, before the cells and tissues can be reviewed under a microscope. The process of tissue fixation, processing, sectioning and histochemical staining takes at least 24 hours.
The fixed and processed samples can be stored for many years and will be available to section and examine again, as formalin-fixed, paraffin-embedded (FFPE) samples.
Figure 6.2 Light Microscopy
6.2.1 Fine Needle Aspiration (FNA) Cytology
Cytology samples that are aspirated from the breast are fixed in alcohol or acetone, spun down and smeared onto a glass slide.
The cells are stained with Papanicolaou (PAP) stain or a modified Giemsa stain or with hematoxylin and eosin (H&E).
6.2.2 Core Needle Biopsy (CNB)
A clip should be placed in the region of a CNB as this will provide documentation of concordance with the target lesion on imaging. The clip will also allow subsequent wire localization of the proper area if the lesion requires excision or if the patient is undergoing neo-adjuvant therapy.
The core needle biopsy (CNB) can be rapidly fixed and processed because of its small size. It is the role of the Pathologist and the laboratory staff to ensure that the ‘core’ of tissue is optimally oriented in the tissue cassette so that the entire core is included in the tissue section.
Preparation of the Core Needle Biopsy Specimen
For core needle biopsies (CNB), optimal tissue fixation is very important. These small samples are placed in a fixative solution immediately and usually for at least six hours; specimens may be fixed more rapidly with the aid of microwave techniques.After the biopsy is processed, H&E-stained sections from one level may be sufficient to allow for a diagnosis to be made of a mass breast lesion. Core biopsies taken for the investigation of micro-calcification require a minimum of three levels to be examined. In difficult cases further levels and immunohistochemical (IHC) studies may be helpful.
Benign Core Needle Biopsy Results
For patients with benign CNB results, there must be pathologic-radiographic ‘concordance.’ Most patients with concordant radiographic-pathologic findings have imaging at between 6 months to 12 months from the time of the breast core needle biopsy.
6.2.3 Excision Biopsy
If a core needle biopsy is non-diagnostic, and the breast mass is too large to remove an incision biopsy can be performed to confirm the diagnosis.
In situations where the core needle biopsy (CNB) is non-diagnostic, or is not concordant with the breast imaging results, or if it yields a ‘high risk’ abnormality (e.g. radial scar, ADH, papilloma or LCIS), excision of the entire lesion is advised.
In some cases, particularly if a palpable breast mass is present, some patients will prefer excision biopsy with removal of the lesion.
Excision biopsy of simple cysts, micro-cysts or cysts with thin septa is not necessary.
Excision biopsies may generate scar tissue inside the breast that may cause concerns on future imaging of the breast, particularly when prior mammograms are not available for comparison.
More about Excision Biopsies
The excision biopsy or excision specimen may include a localization ‘wire’; the excision specimen with the wire in place will be sent to the Pathology Laboratory with a copy of the mammogram. The Pathologist will orientate the specimen to match the mammographic appearance and can also obtain a specimen X-ray.When the area of a mammographic abnormality is confirmed on specimen X-ray and the tissue is fixed, the Pathologist can sample the abnormal breast, identifying each tissue block taken. The excision margins of the specimen may also be sampled and measured macroscopically.
Whole specimen mammography is obligatory for clinically occult lesions excised under mammographic localization and is recommended for palpable lesions that are associated with micro-calcifications (D’Orsi, 1995).
If possible, all specimens should be oriented by the Surgeon. Specimen radiography is essential to confirm the accurate removal of the mammographic abnormality and to guide the pathologist to the appropriate area for sectioning and microscopic study. Visualization of the clip or a tissue reaction to the clip helps the Pathologist and the Surgeon identify the prior biopsy site.
Specimen radiography can also show whether the lesion is in proximity to the edge of the specimen. In such cases, additional tissue may need to be removed to increase the likelihood of negative margins (McCormick et al., 2004).
More about Margins on Excision Biopsies
The best opportunity to achieve clear margins is at the time of the original surgical excision. Some centers use digital imaging devices in the operating room (e.g., Faxitrons) to provide an immediate picture of the specimen and to improve the ability of the Surgeon to see the breast lesion in relation to the excision margin.
Post-excision mammography should be performed three to five weeks following excision of a cancerous lesion to check for residual suspicious calcifications which will require removal.
6.2.4 Frozen Section
‘Frozen section’ analysis uses liquid nitrogen to harden the tissue to allow for thin sectioning.
The tissue is ready for light microscopy within a few minutes, but the cell and tissue morphology will be more difficult to appreciate than the permanently fixed tissue. Frozen section diagnosis can be used when a patient is on the operating table
Figure 6.3 Frozen Section Diagnosis
6.2.5 Lymph Node Sampling
For patients with a suspicious BI-RADS 4c or 5 lesion on mammography, ultrasound scanning of the ipsilateral axilla should be performed to evaluate suspicious abnormal axillary nodes.
Percutaneous fine needle aspiration (FNA) of a ‘suspicious’ lymph node is an accepted intervention.
If malignant cells are present in the axillary lymph node FNA, the patient should be evaluated to determine if an axillary lymph node dissection is necessary at the time of the surgical management of the primary breast cancer.
Sentinel Lymph Nodes
The sentinel lymph node (SLN), or ‘guard node,’ is the lymph node in the axilla where breast cancer will first spread.
To identify these axillary lymph nodes, before surgery the surgeon injects into the breast either a special blue dye or a radio-active isotope (sometimes both). The dye or isotope used will move from the tumor to the lymphatic system. The first node to turn blue or to contain the radioactive material is referred to as the ‘sentinel lymph node (SLN).
Negative and Positive Sentinel Lymph Nodes
If the sentinel lymph node is negative for tumor cells, the remaining lymph nodes are left intact. This selective surgical sampling of the axillary lymph nodes reduces the complication of post-operative lymphedema of the arm.
If the SLN is positive, a decision will be made whether other nearby nodes need to be removed and examined in a future surgical procedure (Cserni et al., 2004).
Ultrasound-guided, core needle biopsy (CNB) of the axillary lymph node with fixation and routine tissue sectioning can identify lymph node metastases. Recent studies have confirmed that lymph node metastases can be identified in up to 80 % of cases. Some studies have shown that CNB of the sentinel lymph node (SLN) is as accurate as excision biopsy in detecting lymph node metastases (Damera et al., 2003; Newman et al., 2006).
6.3 Light Microscopy and Diagnostic Histopathology
For cytology samples and histopathology samples from patients in the breast screening program, there are reporting guidelines for Pathologists who report these samples.
Since 1993 in the UK, the National Coordinating Committee for Breast Cancer Screening Pathology (NCCBSP) has produced Pathology reporting guidelines and has been responsible for quality assurance (QA) in the NHS Breast Screening Program (NHSBSP). This committee has also published guidelines for fine needle aspiration cytology (FNAC) reporting in breast cancer screening, and these have been used in Europe and North America (Ellis et al., 2004).
6.3.1 Reporting FNA Cytology
The process of fine needle aspiration to obtain an adequate amount of cellular material for diagnosis requires some skill. It is not surprising that when small mammographically-detected breast abnormalities are found, there may not be enough cells present in the sample for the Pathologist to make a microscopic diagnosis. Cytology samples can be preserved and prepared for light microscopy quite quickly.
Figure 6.4 Benign, C2 FNAC of the breast
Cohesive sheets of cells without atypia and with some ‘bare nuclei’
of myoepithelial cells in the background. (PAP x 60).
Diagnostic Categories of Tissue Samples
From the years of experience gained by the breast screening program, the following diagnostic categories have been developed:
C1: Inadequate: there are insufficient numbers of cells present to make an assessment.
C2: Benign: there are adequate numbers of cells present and those that are show benign cytology. Cohesive groups of cells may be present without atypia, and there may be some benign bare nuclei of myoepithelial cells.
C3: Atypia, Probably Benign: the aspirate may be hypercellular with some cell nuclear pleomorphism. This category would warrant further assessment of the breast abnormality.
C4: Suspicious for Malignancy: this category should be used for aspirates with highly atypical features although a confident diagnosis cannot be made. There may be for three main reasons for this:
- The specimen is scanty, poorly-preserved or poorly-prepared, but some cells are present with malignant features.
- The sample may show cells with some malignant features, but these are present in the absence of overtly malignant cells.
- The sample has a mainly benign pattern with large numbers of naked nuclei and cohesive sheets of cells, but there are occasional cells showing malignant features.
C5: Malignant: this is an adequate sample that contains carcinoma cells (or other malignant cells).
6.3.2 Reporting Core Needle Biopsies (CNB)
In the 1990’s core biopsy became introduced into the breast screening assessment process following the introduction of automated core biopsy guns. Guidelines for specimen handling and reporting of core needle biopsies (CNB) in breast screening assessment have been developed and implemented (Ellis et al., 2004).
The following diagnostic categories are used for breast cancer pathology reports and CNB samples:-
B1: Normal Tissue: the report should include a description of the normal breast components and whether any micro-calcifications are present.
B2: Benign: there is an identifiable benign abnormality such as fibroadenoma, fibrocystic change, duct ectasia, sclerosing adenosis or abscesses or fat necrosis.
B3: Uncertain Malignant Potential: benign ‘mixed’ lesions or hyperplasias with or without atypia, for example uniform populations of cells involving two or more duct spaces may raise the possibility of low-grade DCIS. Further tissue sampling for assessment may be required. Definitive surgery should not be undertaken as a result of a B3 CNB diagnosis.
B4: Suspicious: this category includes crushed areas containing suspicious cells, but a definitive diagnosis of malignancy can not be made. Also, when there is insufficient material for IHC, this category may be used. Further tissue sampling for assessment may be required. Definitive surgery should not be undertaken as a result of a B4 CNB diagnosis.
B5: Malignant: this category is used for cases of unequivocal malignancy and further categorization into in-situ and invasive malignancy can and should be undertaken if possible.
Key Points of Breast Histology after CNB
There are some key points regarding breast histology on CNB:
‘Lobular neoplasia’ or ‘in-situ lobular neoplasia’ are the preferred terms for core needle biopsy reports; the use of atypical lobular hyperplasia (ALH) or lobular carcinoma in situ (LCIS) are recommended for excision specimens.
Grading of breast cancer on core needle biopsy (CNB) can be performed and is reasonably accurate. Concordance between grade on CNB and in the definitive excision specimen has been reported to be seen in approximately 75% of cases. However, the grade may differ, usually by one level, from that in the subsequent resection specimen.
Tumors in CNB may be identified according to the most common breast tumor categories; ductal or lobular carcinoma.
Assessment of ‘predictive’ factors in CNB have been shown to correlate with their expression in subsequent breast excision specimens and include ER, PR and HER2.
Accuracy and Sensitivity of Core Needle Biopsy
The diagnostic accuracy of CNB has been verified by several studies that have shown good concordance between CNB and subsequent surgical excision specimens (ranging from 91% to 100%) (Parker et al.,1994).
The sensitivity for detection of malignancy on CNB is high in the majority of published studies (85% to 100%) and the specificity is 96% to 100% for stereotactically-guided CNB.
Slightly better results have been documented in ultrasound-guided CNB and vacuum-assisted biopsies (VAB) than in stereotactic, spring-loaded and freehand biopsies and for diagnosis of palpable masses than for calcifications (Fajardo et al., 2004).
6.3.3 Lympho-vascular Invasion (LVI)
Lympho-vascular invasion (LVI) is an important prognostic marker in breast cancer diagnosis.
LVI seen microscopically is associated with an increased risk of metastatic disease and local recurrence and in reduced survival.
LVI may be difficult to detect in CNB, although some studies have shown more than 50% concordance between CNB and excision findings. If LVI is seen in CNB histology, then it is recommended that this finding is included in the descriptive Pathology report.
Figure 6.5 Lympho-vascular Invasion (LVI)
A. Groups of breast cancer cells within a lymphatic space.
B. IHC shows brown cytokeratin staining of metastatic breast
cancer cells in a lymph node.
6.3.4 Micro-vessel Density (MVD)
The estimation of micro-vessel density (MVD) on histology of breast cancer may also predict response to systemic therapy. ‘Angiogenesis’ is a prognostic indicator in breast cancer. Endothelial cell markers such as CD31 and Factor VIII may be used.
In women with non-palpable micro-calcifications, wire localization and excision is tailored to each case by the Radiologist and the Surgeon.
The aim of this procedure is to obtain a histologic diagnosis, to perform complete excision of ‘high-suspicion’ lesion, to excise CNB-proven tumors, or to remove residual suspicious micro-calcifications following excision of malignant calcifications.
6.3.6 Breast Cancer Pathology Report and Lymph Node Specimens
Lymph node metastasis is an important part of cancer Staging (see Section 7) and will affect future treatment.
Metastatic tumor clusters in lymph nodes that measure < 0.2 mm are designated as ‘isolated’ tumor cells.
Discontinuous clusters of metastatic tumor cells are measured as one focus in a definable part of a lymph node. Unevenly dispersed, clustered tumor cells are characterized by the largest cluster.
References
D’Orsi, C.J. (1995). Management of the breast specimen. Radiology 194(2), 297. (Retrieved November 20th 2014): https://www.ncbi.nlm.nih.gov/pubmed/7824700
McCormick, J.T., Keleher, A.J., Tikhomirov, V.B., Budway, R.J., Caushaj, P.F. (2004). Analysis of the use of specimen mammography in breast conservation therapy. Am J Surg 188(4), 433. (Retrieved November 19th 2014): https://www.ncbi.nlm.nih.gov/pubmed/15474443
Patient Information
Breast Cancer Org..Your Guide to the Breast Cancer Pathology Report. (Retrieved January 9th2014):http://www.breastcancer.org/Images/Pathology_Report_Bro_V14_FINAL_tcm8-333315.pdf
National Cancer Institute..Sentinel Lymph Node Biopsy. (Retrieved January 10th2014):http://www.cancer.gov/cancertopics/factsheet/detection/sentinel-node-biopsy
Forward to section 6B on immunohistochemistry. Back to 5D on rare types of cancer in the breast
