View source for Invasive lobular carcinoma

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Invasive lobular carcinoma (ILC):    
==Gross examination==
As per:
*[[Breast biopsy or excision]]
or mastectomy.

==Microscopic evaluation==
[[File:Classic Invasive Lobular Carcinoma of the Breast (6813147194).jpg|thumb|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:<ref name="pmid10816631">{{cite journal  |vauthors=Moore MM, Borossa G, Imbrie JZ, etal |title=Association of Infiltrating Lobular Carcinoma With Positive Surgical Margins After Breast-Conservation Therapy |journal=Ann. Surg. |volume=231 |issue=6 |pages=877–82 |date=June 2000 |pmid=10816631 |pmc=1421077 |doi= 10.1097/00000658-200006000-00012}}</ref><ref name="pmid19092630">{{cite journal |vauthors=Spencer JT, Shutter J |title=Synchronous bilateral invasive lobular breast cancer presenting as carcinomatosis in a male |journal=Am. J. Surg. Pathol. |volume=33 |issue=3 |pages=470–4 |date=March 2009 |pmid=19092630 |doi=10.1097/PAS.0b013e318190d10d }}</ref><ref name="Fletcher">Fletcher's diagnostic histopathology of tumors. 3rd Ed. p. 931-932.</ref>
{| class="wikitable"
|-
! 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
| [[File:Classic Invasive Lobular Carcinoma of the Breast (6813147194).jpg|180px]]
|-
| 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.
| [[File:Histopathology of pleomorphic lobular carcinoma with plasmacytoid cells.jpg|180px|center]]
|}

===Differential diagnosis===
[[File:Histopathology of lobular carcinoma in situ.jpg|thumb|[[Lobular carcinoma in situ]].]]
*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:
<gallery mode=packed heights=180>
File:Invasive ductal carcinoma, with occasional entrapped normal ducts.jpg|thumb|'''[[Invasive ductal carcinoma]]''', with occasional entrapped normal ducts (arrow).
File:Chromogenic immunohistochemistry for E-cadherin in invasive lobular carcinoma, annotated.jpg|'''E-cadherin''' is '''negative''' in invasive '''lobular''' carcinoma (shown), but has membranous staining in [[invasive ductal carcinoma]]
File:Chromogenic immunohistochemistry for p120 in invasive lobular carcinoma.jpg|'''p120''' has '''cytoplasmic''' staining in invasive lobular carcinoma (shown), but has membranous staining in [[invasive ductal carcinoma]]
</gallery>
{{Breast cancer staging}}
{{Evaluation of tumors}}
=== Grading ===
The '''Nottingham system'''<ref>{{cite journal |last1= Elston |first1= CW |last2= Ellis |first2= IO |title= Pathologic prognostic factors in breast cancer. I. The value of histological grades in breast cancer. Experience from a large study with long-term follow-up |journal= Histopathology |year= 1991 |volume= 19 |issue= 5 |pages= 403–10 |pmid= 1757079 |doi=10.1111/j.1365-2559.1991.tb00229.x}} {{cite journal |title= Republished |year= 2002 |doi= 10.1046/j.1365-2559.2002.14892.x | volume=41 |journal=Histopathology |pages=154–161}}</ref> is recommended for breast cancer grading.<ref>{{cite web|title=What is the Nottingham combined histologic grade (modified Scarff-Bloom-Richardson grade) system for breast tumors?|url=https://www.medscape.com/answers/1668113-181367/what-is-the-nottingham-combined-histologic-grade-modified-scarff-bloom-richardson-grade-system-for-breast-tumors|author=Oudai Hassan|website=Medscape}} Updated: Mar 20, 2019</ref> The Nottingham system is also called the Bloom–Richardson–Elston system ('''BRE''')<ref>{{cite journal | last1= Al-Kuraya| first1= Khawla| last2=Schraml | first2=Peter |display-authors=et al | title= Prognostic relevance of gene amplifications and coamplifications in breast cancer | journal=Cancer Research| volume=64 | issue=23 | year=2004| pages= 8534–8540}}</ref>, or the Elston-Ellis modification<ref>Elston CW, Ellis IO. Pathologic prognostic factors in breast cancer. I. The value of histological grades in breast cancer. Experience from a large study with long-term follow-up. Histopathology 1991, 19:403-410.</ref> of the Scarff-Bloom-Richardson grading system.<ref name="BloomRichardson1957">{{Cite journal | last1 = Bloom | first1 = H.J. | last2 = Richardson | first2 = W.W. | title = Histological grading and prognosis in breast cancer; A study of 1409 cases of which 359 have been followed for 15 years | journal = British Journal of Cancer | volume = 11 | issue = 3 | pages = 359–77 | year = 1957 | pmid = 13499785 | pmc = 2073885 | doi=10.1038/bjc.1957.43}}</ref><ref name="Genestie1998">{{Cite journal | last1 = Genestie | first1 = C. | last2 = Zafrani | first2 = B. | last3 = Asselain | first3 = B. | last4 = Fourquet | first4 = A. | last5 = Rozan | first5 = S. | last6 = Validire | first6 = P. | last7 = Vincent-Salomon | first7 = A. | last8 = Sastre-Garau | first8 = X. | title = Comparison of the prognostic value of Scarff-Bloom-Richardson and Nottingham histological grades in a series of 825 cases of breast cancer: Major importance of the mitotic count as a component of both grading systems | journal = Anticancer Research | volume = 18 | issue = 1B | pages = 571–6 | year = 1998 | pmid = 9568179}}</ref> 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.<ref>{{cite web|url=http://surgpathcriteria.stanford.edu/breast/inflobcabr/grading.html|title=Infiltrating Lobular Carcinoma of the Breast|website=Stanford Medicine|accessdate=2021-01-06}}</ref>

==== 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
<gallery mode=packed heights=200>
File:Histopathology of invasive lobular carcinoma with moderate nuclear pleomorphism.jpg|Invasive lobular carcinoma with '''moderate''' nuclear pleomorphism.
</gallery>

==== Mitotic count ====
{{Mitotic count in invasive breast cancer}}

==== 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 evaluation of invasive breast cancer}}
====Estrogen and progesterone receptors====
{{Estrogen and progesterone receptors in breast cancers}}
<gallery>
File:Immunohistochemistry for progesterone in invasive lobular carcinoma, staining 61-70 percent.jpg|Progesterone recepotor, moderate intensity, 61-70% of nuclei.
</gallery>
<noinclude>===Neoadjuvant cases===
{{Microscopic evaluation of neoadjuvant invasive cancer}}
{{Evaluation of tumors}}
{{Reporting of invasive breast cancer}}
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