Breast pathology

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Author: Mikael Häggström [note 1]

Contents

Breast biopsy or excision

Fresh breast specimens should be put in formalin within one hour.[note 2] Breast specimens should be immersed in formalin for 6-72 hours.[1]

Gross processing

Selection and trimming

For excision (also called lumpectomy):

  • Determine total specimen size. ((Weight the specimen[2]))
  • Ink margins. If sample orientations are marked, use different colors for different directions.[2]
  • Palpate the specimen for masses. If felt, estimate the greatest dimension.[note 3] Compare with radiography if available.[2] Confirm the presence of any known biopsy clips, either visibly or by post-operative radiography (in order to confirm that the specimen includes the region of interest).
Cut a lumpectomy in the direction that gives the shortest distance from margin to margin. If a lumpectomy is uneven as shown, cut so that the first and last slice become wedge shaped (because these will later be cut further, perpendicularly to the margin), avoiding a wedge-shape for remaining slices.
  • Serially section the specimen.
  • When performing triage of fresh lumpectomies, generally make slices 1.1 to 1.5 cm thick. When laid down and flattened, this is generally thin enough to allow for fixation over at least 6 hours, and thick enough to be further cut into 2 or 3 slices after fixation; Note the direction of up/down on each such thick slice so that the relative orientation of the thinner slices thereof is maintained. Slices with solid tumors are cut somewhat thinner since they won't flatten as much when laid down.
  • When selecting tissue for submission after fixation, make 3-4 mm thick slices.[2]
  • Inspect for any grossly visible lesions. If found, measure at least the greatest dimension of the lesion on the slice where it appears largest. (Also compare the greatest gross measurement (including any palpated one) with the greatest measurement at previous imaging, and note if it confers a staging discrepancy between imaging and gross dimensions, with cutoffs at 0.1 cm, 0.5 cm, 1.0 cm, 2.0 cm, and 5 cm.)
Re-excisions

Tissue selection

Further serially section each of the two end sections into perpendicular sections, so that the distance between the surgical margin and any tumor involvement can be measured. If they are visibly involved as pictured, sections can be selectively taken from there. If end sections are not grossly involved, submit one perpendicular section, (every other perpendicular section), ((or the entire end sections)).
  • For lumpectomies, submit:[2]
  • Entire specimen if it can fit in 3-5 slices.
  • If larger:
  • For relatively well demarcated tumors: 1 slice per cm of tumor (minimum of 3 slices of tumor), including both center and periphery of tumor, including closest distance to the surgical margin if possible.
  • For diffuse or even invisible tumors such as often is the case for DCIS and ILC, either still submit whole, or use X-ray to guide what tissue to submit.
  • Additional suspicious areas, including those indicated by radiography.
  • ((Representative sections of margins in each direction.))

Breast specimens where breast cancer is possible should generally not be decalcified even when containing small calcifications, to preserve the ability to perform immunohistochemistry.

  See also: General notes on gross processing


Gross report

  • Size of original tissue sample, preferably in 3 dimensions.
  • Description of inking
  • Tumor properties, at least:
  • Size in 3 dimensions.[2]
  • Distance from margins[2]
  • Consistency[2]
  • (Description of sectioning and submissions.)
  • ((Time of procurement and time of placement in formalin.[note 2]))

Example:

(The specimen is received fresh and consists of) an irregular fragment of yellow tan fibrofatty tissue measuring 4.0 x 2.8 x 2.0 cm. (The specimen is oriented with two sutures and) the surgical margins are inked as follows: superior-blue, inferior-green, medial-red, lateral-yellow, anterior-orange, and posterior-black. {{A radioactive seed is embedded in the tissue.}} The tissue is serially sectioned {{to reveal a tan-gray, spiculated, indurated mass measuring _cm in greatest dimension. The mass is located _cm from the nearest (<<superior, inferior etc>>) margin. (The specimen is entirely submitted in sequential sections from medial to lateral in 10 cassettes. The medial and lateral margins are submitted as perpendicular sections.) The specimen was procured at _AM/PM on _/_/2020. The specimen was placed in formalin at _AM/PM on _/_/2020.

Lymph nodes

When lymph nodes are submitted together with a biopsy or excision of a suspected or previously confirmed invasive lobular carcinoma (but not necessarily invasive carcinoma with lobular features), generally put the lymph node specimen through H&E processing at a relative rush. If you don't see any involvement on the H&E stain, order immunostain for CK AE1/AE3 in order to visualize otherwise occult lymph node involvement. The rushing of the lymph node samples allows you to have the immunostained slides by a similar time as the rest of the case.[3]

Further information: Lymph node

Staining

Usually H&E staining.

Microscopic evaluation

If tumor is found, determine:

  • Tumor size
  • Malignancy
  • Distance from excision margin

Malignancy

The most important is to classify a sample as either of the following:

  • Benign
  • Carcinoma in situ
  • Invasive cancer

Most common types

Women seeking evaluation of a breast lump[4]
Finding Relative
incidence
Histopathology Image
Fibrocystic breast changes 40% Sclerosing adenosis (pictured), with an increase in glandular elements in addition to stromal proliferation that distorts and compresses glands.[5] Histopathology of sclerosing adenosis of the breast.jpg
Radial scar, seen as a fibroelastic stroma and entrapped glands radiating outward. Measure the size of these.[note 4] Histopathology of a radial scar of the breast.jpg
Usual ductal hyperplasia: Cohesive proliferation with haphazard, jumbled cell arrangement or streaming growth pattern. Cells have mild variation in cellular and nuclear size and shape.[6] Histopathology of usual ductal hyperplasia.jpg
No disease 30%
Fibroepithelial tumor 7% Proliferation of both stromal and epithelial components.[note 5] The tumor group mainly includes fibroadenoma and phyllodes tumor. Micrograph of a fibroadenoma.jpg
Atypical ductal hyperplasia 7%[7] Epithelial proliferations which are not qualitatively or quantitatively abnormal enough to be classified as ductal carcinoma in situ.[7] Micrograph of atypical ductal hyperplasia.jpg
Other benign mammary dysplasias and neoplasms 5% Including:
  • Flat epithelial atypia: variably dilated acini lined by one to several layers of epithelial cells with low-grade cytologic atypia, usually columnar.[8]
  • Columnar cell change: Terminal duct lobular unit with epithelium exhibiting tall cells with oval or elongated nuclei orientated perpendicularly to the basement membrane.[9]
Histopathology of flat epithelial atypia and columnar cell change.jpg
Intraductal papilloma: unremarkable epithelial cells lining fibrovascular cores. Histopathology of intraductal papilloma.jpg
Pseudoangiomatous stromal hyperplasia (PASH): Complex interanastomosing vessel-like spaces in dense collagenous, keloid-like stroma. Histopathology of pseudoangiomatous stromal hyperplasia (PASH).jpg
Breast cancer (in situ or invasive) 10% See next section.

Breast cancer types

Breast cancer types, with relative incidences and prognoses.
Cancer type Histopathology Image
Invasive ductal carcinoma (IDC) Carcinomatous cells are seen below the basement membrane of lactiferous ducts. Otherwise, there are no specific histologic characteristics, essentially making it a diagnosis of exclusion.[10] Invasive ductal carcinoma, with occasional entrapped normal ducts.jpg
Ductal carcinoma in situ (DCIS) Malignant epithelial cells confined to the ductal system of the breast, without invasion through the basement membrane.[11] File:DCIS - Intraductal carcinoma of the breast.jpg
Invasive lobular carcinoma (ILC) The "classic" pattern is round or ovoid cells with little cytoplasm in a single-file infiltrating pattern, sometimes concentrically giving a targetoid pattern. Classic Invasive Lobular Carcinoma of the Breast (6813147194).jpg
Lobular carcinoma in situ (LCIS)
  • Monomorphic, loosely cohesive, slightly enlarged and evenly spaced cells that fill acini.[12]

Cells have indistinct cell borders, pale cytoplasm, and uniform small nuclei with evenly distributed chromatin and inconspicuous nucleoli.[12]

Histopathology of lobular carcinoma in situ.jpg
Mucinous carcinoma Extracellular mucin areas around tumor cells. Histopathology of mucinous invasive ductal carcinoma of the breast.jpg
Medullary carcinoma Seemingly fused tumor cells (syncytial pattern), and a prominent lymphoid infiltrate. Histopathology of medullary breast carcinoma.jpg
Further information: Evaluation of tumors

Previous biopsy site

(For excisions or larger, look up past biopsies, and if in the same area, look for biopsy sites in order to confirm that the previous biopsy represents the same pathologies.)

If tumor is not found

Check the imaging indication, and look for abnormalities that may explain the diagnostic findings:

  • Dense stromal fibrosis for radiodense areas.
  • Calcifications if found on X-ray.

If still not found, note their absence, since it indicates that the biopsy may have missed the target of interest.

Microscopy report

A normal biopsy may be reported as follows

(Fibrofatty tissue with benign ducts and lobules.) Negative for (atypia and) malignancy.

More detailed reports are given at the disease-related articles.


Fibrocystic breast changes

Microscopic examination

Types:

Differential diagnosis

Sclerosing adenosis may look similar to invasive ductal carcinoma (IDC), but IDC will:[14]

  • Not be lobular at low power
  • Have marked cellular atypia
  • Have no myoepithelial cells surrounding ducts.

When unsure, perform immunohistochemistry for myoepithelial markers (preferably p63 and calponin in breast lesions):

Immunostain with a myoepithelial marker (calponin) in sclerosing adenosis, showing myoepithelial cells surrounding the ducts, thereby excluding invasive carcinoma.


Fibroepithelial tumor

Gross examination

As per:

or mastectomy.

Microscopic evaluation

Fibroadenoma

Characteristics of fibroepithelial tumor

Biplastic, having proliferation of both stromal and epithelial components,[note 6] arranged into either a pericanalicular pattern (stromal proliferation around epithelial structures), or an intracanalicular pattern (stromal proliferation compressing the epithelial structures into clefts).

Characteristics of fibroadenoma

Fibroadenomas characteristically display hypovascular stroma compared to malignant tumors.[15][16][17] Furthermore, the epithelial proliferation appears in a single terminal ductal unit and has duct-like spaces surrounded by a fibroblastic stroma. The basement membrane is intact.[18]

Characteristics of phyllodes tumor

Benign phyllodes tumor

In contrast to fibroadenomas, phyllodes tumors display a leaf-like architecture, and an increased stromal cellularity.[19] In needle biopsy specimens, phyllodes tumors can be diagnosed in a fibroepithelial tumor if there is prominent mitotic activity of ≥3 per 10 high power fields, or the finding of 3 or more of the following characteristic histologic features:[19]

  • Stromal overgrowth
  • Fat infiltration
  • Stromal fragmentation
  • Subepithelial stromal condensation
  • Stromal nuclear pleomorphism

Further workup

After diagnosing a fibroepithelial tumor, still exclude another type of breast cancer, which may arise within it:[20]

Breast cancer types

Breast cancer types, with relative incidences and prognoses.
Cancer type Histopathology Image
Invasive ductal carcinoma (IDC) Carcinomatous cells are seen below the basement membrane of lactiferous ducts. Otherwise, there are no specific histologic characteristics, essentially making it a diagnosis of exclusion.[21] Invasive ductal carcinoma, with occasional entrapped normal ducts.jpg
Ductal carcinoma in situ (DCIS) Malignant epithelial cells confined to the ductal system of the breast, without invasion through the basement membrane.[11] File:DCIS - Intraductal carcinoma of the breast.jpg
Invasive lobular carcinoma (ILC) The "classic" pattern is round or ovoid cells with little cytoplasm in a single-file infiltrating pattern, sometimes concentrically giving a targetoid pattern. Classic Invasive Lobular Carcinoma of the Breast (6813147194).jpg
Lobular carcinoma in situ (LCIS)
  • Monomorphic, loosely cohesive, slightly enlarged and evenly spaced cells that fill acini.[12]

Cells have indistinct cell borders, pale cytoplasm, and uniform small nuclei with evenly distributed chromatin and inconspicuous nucleoli.[12]

Histopathology of lobular carcinoma in situ.jpg
Mucinous carcinoma Extracellular mucin areas around tumor cells. Histopathology of mucinous invasive ductal carcinoma of the breast.jpg
Medullary carcinoma Seemingly fused tumor cells (syncytial pattern), and a prominent lymphoid infiltrate. Histopathology of medullary breast carcinoma.jpg

Microscopic report

If, even after consultation, it is not clear whether a tumor is a fibroadenoma or phyllodes tumor, then it can be reported as a cellular fibroepithelial lesion or a fibroepithelial neoplasm.

A phyllodes tumor warrants a comment whether margins are positive or negative for tumor, whereas fibroadenoma does not need such comment.

Example report of fibroadenoma:

Right breast, lumpectomy:

Fibroadenoma.
Negative for atypia or malignancy.

Atypical ductal hyperplasia

Gross examination

As per:

or mastectomy.

Microscopic evaluation

Histological appearance of atypical ductal hyperplasia (ADH) and immunohistochemical phenotype:[22]
- A - One focus (< 2 mm) of two architecturally disarranged cross sections of tubuli showing a monotonous intraductal proliferation with secondary intraluminal architecture.
- B - One area of an ADH with associated intraluminal calcifications.
- C - Higher magnification of ADH shows low-grade nuclear atypia and monotonous cell proliferation along with secondary intraluminal architecture.
- D - Strong and uniform expression of estrogen receptors (ER). ER immunohistochemistry.
- E - Lack of basal cytokeratins (CK5/6). CK5/6 immunohistochemistry.

Atypical ductal hyperplasia shows epithelial proliferations which are not qualitatively or quantitatively abnormal enough to be classified as ductal carcinoma in situ.[7]

Differential diagnoses

Ductal carcinoma in situ

There is no single definite cutoff that separates atypical ductal hyperplasia from ductal carcinoma in situ, but the following are important distinctive features of atypical ductal hyperplasia, with suggested cutoffs:[23]

  • Size less than 2 mm.
  • Not involving more than one duct.
  • The atypical epithelial proliferation is admixed with a second population of proliferative cells without atypia.
  • The proliferation completely involves the terminal ductal lobular unit(s), to a limited extent.

Also, ADH tends to have rounded lacunae between cells, in contrast to more crescent-shaped (compressed) lucunae in DCIS.

Usual ductal hyperplasia (UDH)

edit
In contrast to usual ductal hyperplasia (UDH), atypical ductal hyperplasia (ADH) displays:[6]

  • Increased amounts of pale eosinophilic to amphophilic cytoplasm with conspicuous cell borders
  • Atypical architectural patterns, including cribriform spaces, Roman arches, trabecular bars and micropapillae

If uncertain, immunohistochemistry can be performed:[6]

Usual ductal hyperplasia (UDH) Atypical ductal hyperplasia (ADH)
High molecular weight keratins Mosaic to occasionally diffuse Negative
Estrogen receptor Heterogenous staining Diffusely positive


Invasive ductal carcinoma

Author: Mikael Häggström [note 1]
Ductal carcinoma in situ (DCIS):

Comprehensiveness

On this resource, the following formatting is used for comprehensiveness:

  • Minimal depth
  • (Moderate depth)
  • ((Comprehensive))

Gross examination

As per:

or mastectomy.

Microscopic evaluation

DCIS.

Malignant epithelial cells confined to the ductal system of the breast.[11] The cells are cohesive and have high grade atypia.[24]

Differential diagnoses

Invasive ductal carcinoma
Has invasion through the basement membrane of over 1 mm in size.[25]

In uncertain cases, use immunohistochemistry stain for calponin (has the highest sensitivity) and p63 (has the highest specificity).

Atypical ductal hyperplasia

There is no single definite cutoff, but the following are suggested cutoffs defining a ductal carcinoma in situ:[23]

  • Size over 2 mm.
  • Involving more than one duct.
Lobular carcinoma in situ (LCIS)

When unsure, perform immunohistochemistry for E-cadherin and p120. Both E-cadherin (left image below) and p120 (right) have a membranous staining pattern in ductal carcinoma in situ:

In contrast:

Grading

At least a low/intermediate/high grading (by Van Nuys criteria) as follows:[28]

Low grade DCIS
  • Nuclei 10-15 microns (2-3 times the size of a red blood cell)
  • Nuclei oval, round, regular, evenly dispersed chromatin up to mildly irregular and minimally pleomorphic
  • Nucleoi, if present, are small and indistinct
Intermediate grade DCIS
  • Same nuclear features as low grade
  • Substantial tumor cell (comedo) necrosis is present
High grade DCIS
  • Nuclei >15 microns (over 3 times the size of a red blood cell)
  • Nuclei are pleomorphic with clumped chromatin
  • Nucleoli are prominent, enlarged
  • Necrosis is almost universal and lumenal

(Numerical grading

Use the low/intermediate/high grade to give a numerical grading as follows:[29]

Feature Points
1 2 3
Nuclear grade Low Intermediate High
Glands/papillae >75% 10% - 75% <10%
Mitotic rate (per 10 HPF) <1 1 - 2 >2
Central necrosis <10% 10% - 50% >50%

The points for each feature are added together, giving the following result:[29]

  • 4 - 7 points: Grade 1
  • 8 - 9 points: Grade 2
  • 10 - 12 points: Grade 3

)

Estrogen and progesterone receptors

In DCIS with necrosis, only use the areas of viable DCIS for the calculation of hormone receptors on immunohistochemistry.

Generally perform immunohistochemistry for estrogen and progesterone receptors and calculate the percentage of positive tumor cells.

HER2

((HER2 testing is not necessary, but can be done for prognostic profiling.[30])) See invasive ductal carcinoma for how to evaluate HER2.

Reporting

Example:

Left breast mass, 2:00, 1 cm from nipple, ultrasound-guided vacuum assisted core needle biopsy:
Ductal carcinoma in situ.
Negative for invasive carcinoma.

For cancers, generally include a synoptic report, such as per College of American Pathologists (CAP) protocols at cap.org/protocols-and-guidelines.

  See also: General notes on reporting


Notes

  1. 1.0 1.1 For a full list of contributors, see article history. Creators of images are attributed at the image description pages, seen by clicking on the images. See Patholines:Authorship for details.
  2. 2.0 2.1 An increased cold ischemia time (time from procurement to time in formalin) negatively effects the utility of immunohistochemistry.
    - Khoury, Thaer (2018). "Delay to Formalin Fixation (Cold Ischemia Time) Effect on Breast Cancer Molecules ". American Journal of Clinical Pathology 149 (4): 275–292. doi:10.1093/ajcp/aqx164. ISSN 0002-9173. 
  3. A palpated greatest dimension before cutting is still superior to trying to align cut pieces together or mathematically adding the thicknesses of involved slices.
  4. Size is a major factor in whether to fully excise radial scars, at an approximate cutoff at around 1 cm.
  5. The proliferation of two histological components is called "biplasia", from Latin bis (“twice”) and -plasia (“formation”), or "biphasic proliferation"
  6. The proliferation of two histological components is called "biplasia", from Latin bis (“twice”) and -plasia (“formation”), or "biphasic proliferation" (although the latter may refer to proliferation that has two chronological phases).
  7. For myoepithelial markers, a combination of p63 and calponin is generally recommended for breast lesions. D2-40 is useful for highlighting lymphatics for invasion.

Main page

References

  1. . Recommendations for HER2 Testing in Breast Cancer: ASCO – CAP Clinical Practice Guideline Update. College of American Pathologists (2013-10-17).
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Monika Roychowdhury. Grossing (histologic sampling) of breast lesions. Pathologyoutlines.com. Topic Completed: 1 August 2012. Revised: 19 September 2019
  3. Chandler IP, Oommen R, Lawson CW (2003). "Invasive lobular carcinoma and cytokeratin immunohistochemistry: an audit. ". J Clin Pathol 56 (3): 240. doi:10.1136/jcp.56.3.240. PMID 12610108. PMC: 1769908. Archived from the original. . 
  4. Mitchell, Richard Sheppard; Kumar, Vinay; Abbas, Abul K.; Fausto, Nelson (2007). Robbins Basic Pathology (8th ed.). Philadelphia: Saunders. p. 739. ISBN 978-1-4160-2973-1. 
  5. Jaya Ruth Asirvatham, M.B.B.S., Julie M. Jorns, M.D.. Breast - Fibrocystic changes - Sclerosing adenosis. Pathology Outlines. Topic Completed: 1 January 2015. Minor changes: 31 December 2020
  6. 6.0 6.1 6.2 Sofia Lérias, M.D., Melinda Lerwill, M.D.. Usual ductal hyperplasia. Pathology Outlines. Last author update: 11 February 2021. Last staff update: 25 April 2022
  7. 7.0 7.1 7.2 David J. Myers; Andrew L. Walls.. Atypical Breast Hyperplasia. StatPearls, National Center for Biotechnology Information. Last Update: February 15, 2019.
  8. Schnitt, Stuart J (2003). "The diagnosis and management of pre-invasive breast disease: Flat epithelial atypia – classification, pathologic features and clinical significance ". Breast Cancer Research 5 (5). doi:10.1186/bcr625. ISSN 1465-542X. 
  9. Logullo, Angela Flavia; Nimir, Cristiane (2019). "Columnar cell lesions of the breast: a practical review for the pathologist ". Surgical and Experimental Pathology 2 (1). doi:10.1186/s42047-018-0027-2. ISSN 2520-8454. 
  10. Peter Abdelmessieh. Breast Cancer Histology. Medscape. Retrieved on 2019-10-04. Updated: May 24, 2018
  11. 11.0 11.1 11.2 Siziopikou, Kalliopi P. (2013). "Ductal Carcinoma In Situ of the Breast: Current Concepts and Future Directions ". Archives of Pathology & Laboratory Medicine 137 (4): 462–466. doi:10.5858/arpa.2012-0078-RA. ISSN 0003-9985. 
  12. 12.0 12.1 12.2 12.3 Sucheta Srivastava. Breast - Noninvasive lobular neoplasia - LCIS classic. Topic Completed: 1 September 2017. Minor changes: 21 June 2020
  13. Nassar, Lara; Baassiri, Amro; Salah, Fatima; Barakat, Andrew; Najem, Elie; Boulos, Fouad; Berjawi, Ghina (2019). "Stromal Fibrosis of the Breast: A Spectrum of Benign to Malignant Imaging Appearances ". Radiology Research and Practice 2019: 1–6. doi:10.1155/2019/5045908. ISSN 2090-1941. 
  14. 14.0 14.1 Jaya Ruth Asirvatham, M.B.B.S., Julie M. Jorns, M.D.. Breast - Fibrocystic changes - Sclerosing adenosis. Pathology Outlines. Topic Completed: 1 January 2015. Minor changes: 31 December 2020
  15. Tavassoli, F.A., ed (2003). World Health Organization Classification of Tumours: Pathology & Genetics: Tumours of the breast and female genital organs . Lyon: IARC Press. ISBN 978-92-832-2412-9. 
  16. Jaya Ruth Asirvatham, M.B.B.S., Carlos C. Diez Freire, M.D., Cansu Karakas, M.D., Belinda Lategan, M.D., Nat Pernick, M.D., Emily S. Reisenbichler, M.D., Monika Roychowdhury, M.D., Mary Ann Gimenez Sanders, M.D, Ph.D., Gary Tozbikian, M.D., Hind Warzecha, M.D. Senior Authors: Julie M. Jorns, M.D., Shahla Masood. Breast nonmalignant, Fibroepithelial neoplasms, Fibroadenoma. Retrieved on 2019-11-04. Revised: 31 October 2019
  17. Rosen, PP. (2009). Rosen's Breast Pathology (3rd ed.). ISBN 978-0-7817-7137-5. 
  18. . Fibroadenoma of the breast.
  19. 19.0 19.1 Gary Tozbikian, M.D.. Breast - Fibroepithelial tumors - Fibroadenoma. Last author update: 19 July 2021. Last staff update: 22 July 2021
  20. Richard L Kempson MD, Robert V Rouse MD. Fibroadenoma of the Breast. Stanford University School of Medicine. May 27, 2006
  21. Peter Abdelmessieh. Breast Cancer Histology. Medscape. Retrieved on 2019-10-04. Updated: May 24, 2018
  22. Rageth, Christoph J.; Rubenov, Ravit; Bronz, Cristian; Dietrich, Daniel; Tausch, Christoph; Rodewald, Ann-Katrin; Varga, Zsuzsanna (2018). "Atypical ductal hyperplasia and the risk of underestimation: tissue sampling method, multifocality, and associated calcification significantly influence the diagnostic upgrade rate based on subsequent surgical specimens ". Breast Cancer 26 (4): 452–458. doi:10.1007/s12282-018-00943-2. ISSN 1340-6868.  This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/)
  23. 23.0 23.1 Tozbikian, Gary; Brogi, Edi; Vallejo, Christina E.; Giri, Dilip; Murray, Melissa; Catalano, Jeffrey; Olcese, Cristina; Van Zee, Kimberly J.; et al. (2016). "Atypical Ductal Hyperplasia Bordering on Ductal Carcinoma In Situ ". International Journal of Surgical Pathology 25 (2): 100–107. doi:10.1177/1066896916662154. ISSN 1066-8969. 
  24. Sucheta Srivastava, M.D.. Breast - Noninvasive lobular neoplasia - LCIS classic (Differential diagnosis section). Topic Completed: 1 September 2017. Minor changes: 17 May 2021
  25. . Protocol for the Examination of Resection Specimens from Patients with Ductal Carcinoma In Situ (DCIS) of the Breast, Version: 4.4.0.0. Protocol Posting Date: June 2021. College of American Pathologists.
  26. Image annotation by Mikael Häggström, MD, using source image from:
    Moatasim A, Mamoon N (2022). "Primary Breast Mucinous Cystadenocarcinoma and Review of Literature. ". Cureus 14 (3): e23098. doi:10.7759/cureus.23098. PMID 35464581. PMC: 8997314. Archived from the original. . 
    - "This is an open access article distributed under the terms of the Creative Commons Attribution License CC BY 4.0."
    Source for microinvasion: . Protocol for the Examination of Resection Specimens from Patients with Ductal Carcinoma In Situ (DCIS) of the Breast, Version: 4.4.0.0. Protocol Posting Date: June 2021. College of American Pathologists.
  27. Gary Tozbikian, M.D.. Breast - Ductal carcinoma in situ - DCIS. pathologyOutlines. Topic Completed: 20 May 2020. Minor changes: 6 May 2021
  28. . Ductal Carcinoma in Situ of the Breast. Stanford Medical School (2020-08-27).
  29. 29.0 29.1 Allred, D. C. (2010). "Ductal Carcinoma In Situ: Terminology, Classification, and Natural History ". JNCI Monographs 2010 (41): 134–138. doi:10.1093/jncimonographs/lgq035. ISSN 1052-6773. 
  30. Laura C Collins, MD, Christine Laronga, MD, FACS, Julia S Wong, MD. Ductal carcinoma in situ: Treatment and prognosis. UpToDate. Literature review current through: Sep 2022. | This topic last updated: Aug 19, 2022.

Image sources

Invasive lobular carcinoma

Invasive lobular carcinoma (ILC):

Gross examination

As per:

or mastectomy.

Microscopic evaluation

Invasive lobular carcinoma.

Characteristics

The "classic" pattern is round or ovoid cells with little cytoplasm in a single-file infiltrating pattern, sometimes concentrically giving a targetoid pattern.

Subtyping

The histologic patterns mainly include:[1][2][3]

Type Prevalence Description Image
Classical 40% Round or ovoid cells with little cytoplasm in a single-file infiltrating pattern, sometimes concentrically giving a targetoid pattern Classic Invasive Lobular Carcinoma of the Breast (6813147194).jpg
Mixed 40% No dominant pattern
Solid 10% Sheets of classical-appearing cells with little intervening stroma.
Alveolar 5% Aggregates of classical-appearing cells
Tubulolobular 5% Cells form microtubules in >90% of tumor (smaller than in tubular carcinoma)
Pleomorphic Classical-appearing but with pleomorphic cells. It may include signet-ring cells, or plasmacytoid cells (pictured) which have abundant cytoplasm and eccentric nuclei.
Histopathology of pleomorphic lobular carcinoma with plasmacytoid cells.jpg

Differential diagnosis

  • In invasive lobular carcinoma, malignant cells have penetrated the basement membrane, in contrast to lobular carcinoma in situ.
  • Invasive ductal carcinoma typically has duct-forming tumor cells rather than single files of tumor cells. In uncertain cases, stain for E-cadherin and p120:

Staging

Stage by the TNM system as follows in sections below.

Also, look for any angiolymphatic invasion. If present, check whether it reaches outside the tumor, and if so, how far.[4] Give greatest dimension (,or 3 dimensions, generally by adding up the estimated thicknesses of involved slices)).[4]

Primary Tumor (T)

Tumor – Depends on the tumor at the primary site of origin, as follows:[5]

Measurements can be made by marking the tumor on microscopy, and then measuring between the markings, which may overlap between multiple slides as shown.
  • T1: Less than 2 cm
  • T1a: 0.1 to 0.5 cm
  • T1b: 0.5 to 1.0 cm
  • T1c: 1.0 to 2.0 cm
  • T2: 2 to 5 cm
  • T3: Larger than 5 cm
  • T4
  • T4a: Chest wall involvement
  • T4b: Skin involvement
  • T4c: Both 4a and 4b
  • T4d: Inflammatory breast cancer, a clinical circumstance where typical skin changes involve at least a third of the breast.

Regional Lymph Nodes (N)

Lymph Node: The lymph node values depend on the number, size and location of breast cancer cell deposits in various regional lymph nodes, such as the armpit (axillary lymph nodes), the collar area (supraclavicular lymph nodes), and inside the chest (internal mammary lymph nodes.)[6][7] Each stage is as follows:[5]

  • N0: There is some nuance to the official definitions for N0 disease, which includes:
  • N0(i+) : Isolated Tumor Cell clusters (ITC),[4] which are small clusters of cells not greater than 0.2 mm, or single tumor cells, or a cluster of fewer than 200 cells in a single histologic cross-section, whether detected by routine histology or immunohistochemistry;
  • N0(mol-): regional lymph nodes have no metastases histologically, but have positive molecular findings (RT-PCR).
  • N1: Mobile ipsilateral axillary nodes. Lymph node clusters 0.2 - 2.0 mm can be called "micrometastasis". At least one carcinoma focus over 2.0 mm is called "Lymph node metastasis". If one node qualifies as metastasis, count all other nodes even with smaller foci as metastases as well.[4]

Critical numbers of involved nodes: 1-3, 4-9, and 10 and over. Note any extranodal extension.[4]

  • N2: Fixed/matted ipsilateral axillary nodes.
  • N3
  • N3a – Ipsilateral infraclavicular nodes
  • N3b – Ipsilateral internal mammary nodes
  • N3c – Ipsilateral supraclavicular nodes

Distant Metastases (M)

  • M0: No clinical or radiographic evidence of distant metastases
  • M0(i+): Molecularly or microscopically detected tumor cells in circulating blood, bone marrow or non-regional nodal tissue, no larger than 0.2 mm, and without clinical or radiographic evidence or symptoms or signs of metastases, and which, perhaps counter-intuitively, does not change the stage grouping, as staging for in M0(i+) is done according to the T and N values
  • M1: Distant detectable metastases as determined by classic clinical and radiographic means, and/or metastasis that are histologically larger than 0.2 mm.

Overall stage

A combination of T, N and M, as follows:[5]

  • Stage 0: Tis
  • Stage I: T1N0
  • Stage II: T2N0, T3N0 T0N1, T1N1, or T2N1
  • Stage III: Invasion into skin and/or ribs, matted lymph nodes, T3N1, T0N2, T1N2, T2N2, T3N2, AnyT N3, T4 any N, locally advanced breast cancer
  • Stage IV: M1, advanced breast cancer
Further information: Evaluation of tumors

Grading

The Nottingham system[8] is recommended for breast cancer grading.[9] The Nottingham system is also called the Bloom–Richardson–Elston system (BRE)[10], or the Elston-Ellis modification[11] of the Scarff-Bloom-Richardson grading system.[12][13] It grades breast carcinomas by adding up scores for tubule formation, nuclear pleomorphism, and mitotic count, each of which is given 1 to 3 points. The scores for each of these three criteria are then added together to give an overall final score and corresponding grade as follows.

Tubule formation

By definition, tubule formation in classic invasive lobular carcinoma is scored as 3.[14]

Nuclear pleomorphism

Such as nuclei being larger, darker, or irregular/pleomorphic. Note: The cancer areas having cells with the greatest atypia should be evaluated.

  • 1 point: nuclei with minimal or mild variation in size and shape
  • 2 points: nuclei with moderate variation in size and shape
  • 3 points: nuclei with marked variation in size and shape

Mitotic count

Mitosis appearances in breast cancer

edit
Mitotic figures are counted only at the periphery of the tumor, and counting should begin in the most mitotically active areas, and in at least 10 high-power fields (HPFs). If you know that the area of your high power field is about 0.2mm2, then you may score mitotic count as follows:[15]

  • 1 point: ≤7 mitoses per 10 HPFs
  • 2 points: 8 to 14 mitoses per 10 HPFs
  • 3 points: ≥15 mitoses per 10 HPFs

If you have a significant different HPF area or you are not sure, count 10 HPFs and calculate the number of mitoses per mm2 (Further information: Evaluation#Counts per mm2 ):

  • 1 point: ≤3 mitoses per mm2
  • 2 points: 4 to 7 mitoses per mm2
  • 3 points: ≥7 mitoses per mm2

A table of counts for various HPF sizes is available at the College of American Pathologists. [1]

Overall grade

The scores for each of these three criteria are added together to give a final overall score and a corresponding grade as follows:

  • 3-5 Grade 1 tumor (well-differentiated). Best prognosis.
  • 6-7 Grade 2 tumor (moderately differentiated). Medium prognosis.
  • 8-9 Grade 3 tumor (poorly differentiated). Worst prognosis.

Immunohistochemistry

Ki-67 index

Ki-67 in an invasive breast cancer: cancer nuclei are stained (brown). There is tumor cell positivity in 70% of the cells (Ki-67 labelling index = 70%).
To count as Ki-67 positive, a nucleus should:
- Not be located in stroma.
- Be at least half within the field of view.
- Be large enough.
Otherwise, even weakly positive nuclei count as positive.

Ki-67 index is mainly relevant in those with stage T1-T2, N0-N1, to determine if chemotherapy is needed (if Ki67 is >30% rather than <5%).[16]

Ki-67 index is most feasibly quantified by a hot spot method,[note 1] Hot spots are areas in which Ki-67 staining is particularly higher relative to the adjacent tumor areas.[17] Usually, the invasive edge of a tumor is a hot spot.[17] When a tumor had several hot spots, the “hottest” spot is selected.[17] Aim to count at least 500 cells in each case, but this is not always possible in cases with low tumor cell density and small tumor size.[17] Also aim to include at least three high-power (×40 objective) fields. Count a nucleus as “positive” if there is any definite brown staining in the nucleus of an invasive breast cancer cell, above the surrounding background in the cytoplasm and extracellular matrix.[18] If a comparisons must be made between core biopsies and sections from an excision, evaluation of the latter should be across the whole tumor.[16] Only nuclear staining counts. Staining intensity of a positive nucleus is not relevant.[16]

HER2

HER2 can initially be evaluated by immunohistochemistry (IHC) or fluorescence in situ hybridization (FISH). If IHC is performed first and is borderline/equivocal, then FISH is recommended.[19] If FISH is performed first and indicates that further workup is required, then IHC may be the performed as per established algorithms.[note 2]

HER2 immunohistochemistry
Immunohistochemistry
Score[20][21] Pattern[22] Status[20][21]
0 Either:[22]
  • No staining observed.
  • Incomplete membrane staining that is faint or barely perceptible and within ≤10% of the invasive tumor cells
HER2 negative
(not present)
1+ Incomplete membrane staining that is faint or barely perceptible and within >10% of the invasive tumor cells.[22]
2+ Weak to moderate complete membrane staining observed in >10% of tumor cells.[22] Borderline/Equivocal
3+ Circumferential membrane staining that is complete, intense, and in >10% of tumor cells.[22] HER2 positive

Micrographs showing each score:[23]

HER2 FISH

HER2 FISH usually uses chromosome enumeration probe 17 (CEP17) to count the amount of chromosomes. Hence, the HER2/CEP17 ratio reflects any amplification of HER2 as compared to the number of chromosomes.

To prepare a slide for HER2 testing, you may need to choose a paraffin-embedded and mark the resulting slide so that you or whoever interprets it knows where to look for the target tumor cells. When there are multiple blocks of the same case, choose the the one with most tumor. (If a block has undergone sectioning for immunohistochemistry (such as ER, PR and/or Ki67) make sure that you have a new H&E slide at a level next to the one to be used for FISH, so that they will correlate better.) In cases of both invasive and in situ carcinoma in the same specimen, mark all invasive carcinoma (also for crushed tissue or with other artifacts) but not the in situ carcinoma. Also mark a small area of normal tissue as an internal control. If possible, it should be a bit away from the tumor, even if only consisting of fatty tissue.

To interpret a HER2 FISH study, first perform a quality control check of the slide as per manufacturer and/or local protocol (generally including checking for proper signals from a control specimen). In cases of both invasive and in situ carcinoma in the same specimen, only score the invasive cells. The signals of 20 cells are usually counted. Also focus up and down on each nucleus to find all signals therein.

If a cytotechnologist has already performed a count, you do not have to recount, but make sure the count is reasonable regarding what you see. In any case, also look around for any obvious tumor heterogeneity in HER2 signals.

If the HER2/CEP17 ratio is borderline (1.8-2.2), count an additional 20 nuclei and recalculate a ratio for the total of 40 nuclei.

Classification of HER2 by fluorescence in situ hybridization (FISH)[note 2]
HER2/CEP17 ratio
≥2.0 <2.0
Average HER2 copy number per cell ≥4.0 HER2 positive Additional work-up required[note 2]
<4.0 Additional work-up required[note 2] HER2 negative

If the initial HER2 result is negative for a needle biopsy of a primary breast cancer, a new HER2 test may be performed on the subsequent breast excision.[note 2]

Biomarker retesting

((If the previous biopsy was negative for ER and PR receptors, and the patient has undergone neoadjuvant chemotherapy before excision, then retest ER/PR on the excision.))[note 3]

In breast cancer metastases, retest estrogen and progesterone receptors, and HER2 in the following circumstances:[25]

  • If the status of the primary tumor is unknown or negative for ER/PR and/or HER2
  • If the primary tumor is heterogeneous for ER/PR expression
  • If the metastatic progression is unusual for the tumor characteristics
  • If the relapse is unexpectedly early or late
  • If unusual metastasis location
  • If the initial test was performed more than 10 years ago
  • If the testing turnaround time are relatively short (to reduce potential delays in patient management by retesting)

Estrogen and progesterone receptors

Generally perform immunohistochemistry for estrogen and progesterone receptors and calculate the percentage of positive tumor cells.


Lobular carcinoma in situ

Fixation

Generally 10% neutral buffered formalin.

Histopathology of lobular carcinoma in situ.jpg

Microscopic evaluation

Lobular carcinoma in situ (LCIS) typically display monomorphic, loosely cohesive, slightly enlarged and evenly spaced cells that fill acini.[26] Cells have indistinct cell borders, pale cytoplasm, and uniform small nuclei with evenly distributed chromatin and inconspicuous nucleoli.[26]

Differential diagnosis

The main differential diagnosis is ductal carcinoma in situ (DCIS).

When unsure, perform immunohistochemistry for E-cadherin and p120:

In contrast, both E-cadherin (left image below) and p120 (right) have a membranous staining pattern in ductal carcinoma in situ (DCIS).

Biomarkers

Generally perform immunohistochemistry for estrogen and progesterone receptors and calculate the percentage of positive tumor cells.

Microscopic report

It should contain:[28]

  • Type of resection or biopsy, and location
  • Results of any supplementary studies performed
  • Extent

However, grading and staging is not applicable. (Margins of excision are not relevant)

Notes

  1. Besides from a hot spot method of Ki67 counting, there is also a IKWG global average method which is more comprehensive. However, the inter-observer difference between the hot spot method and the 'IKWG global average is not statistically significant, and has not shown any significant difference in clinical outcome (theoretically, the area of highest Ki-67 proliferative index is probably most likely to correlate with malignant transformation and risk of metastasis, making the hot spot both more straightforward and clinically relevant than a global average).
    - Reference and instructions for the
    IKWG global average method: Dowsett, M.; Nielsen, T. O.; A'Hern, R.; Bartlett, J.; Coombes, R. C.; Cuzick, J.; Ellis, M.; Henry, N. L.; et al. (2011). "Assessment of Ki67 in Breast Cancer: Recommendations from the International Ki67 in Breast Cancer Working Group ". JNCI Journal of the National Cancer Institute 103 (22): 1656–1664. doi:10.1093/jnci/djr393. ISSN 0027-8874. 
  2. 2.0 2.1 2.2 2.3 2.4 2.5 If additional work-up is required by FISH study, see source article for detailed algorithms:
    Wolff AC, Hammond MEH, Allison KH, Harvey BE, Mangu PB, Bartlett JMS (2018). "Human Epidermal Growth Factor Receptor 2 Testing in Breast Cancer: American Society of Clinical Oncology/College of American Pathologists Clinical Practice Guideline Focused Update. ". J Clin Oncol 36 (20): 2105-2122. doi:10.1200/JCO.2018.77.8738. PMID 29846122. Archived from the original. . 
  3. Retesting ER/PR on any excision with previously negative ER/PR on biopsy on a patient having received neoadjuvant therapy has no scientific support nor opposition.
    - William M Sikov, MD, FACP, FNCBCJudy C Boughey, MD, FACSZahraa Al-Hilli, MD, FACS, FRCSI. General principles of neoadjuvant management of breast cancer. UpToDate.

Main page

References

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Image sources