View source for Breast pathology

The '''breast''' is an important organ for the continuance of the species and one that [[pathologist]]s see quite often because it is often afflicted by [[breast cancer|cancer]].  Before women started [[smoking]] in large numbers, it was the number one cause of cancer death in women (in Canada).  

Fortunately, breast cancer, these days, has a relatively good prognosis if it is detected early... and this is why there are week-ends to end breast cancer -- there are large numbers of breast cancer survivors that are well, wealthy and can advocate for better care and research into breast cancer.

The world of pathology can neatly be divided into two... those that like the breast and those that don't.

=Clinical=
Classic presentation:
*Nipple discharge.
*Pain.
*Breast lump/mass.
*New nipple inversion.
*Skin changes, e.g. ''peau d'orange''.

Most common presentation:
*Abnormal/suspicious screening mammogram - suspicious microcalcifications and/or suspicious mass.

===Breast cancer screening===
Breast cancer screening, for normal risk individuals, starts at age 50 in Canada.  In the USA, breast screening starts at age 40.  

Radiologic screening is less effective in younger individual as: 
# The breast is more dense and thus radiologically more difficult to interpret, and
# The incidence of breast cancer is lower.

===Breast radiology===
BI-RADS = Breast Imaging Reporting And Data System<ref>URL: [http://breastcancer.about.com/od/diagnosis/a/birads.htm http://breastcancer.about.com/od/diagnosis/a/birads.htm]. Accessed on: 16 March 2011.</ref>

*0: Incomplete - come back for more imaging (radiologist ''cha-ching''). 
*1: Negative.
*2: Benign finding(s).
*3: Probably benign -- often short follow-up.
*4: Suspicious abnormality -- needs biopsy.
*5: Highly suggestive of malignancy.
*6: Pathologist says there is a malignancy.

=Specimens=
Breast comes in three main flavours:
#Core needle biopsy (CNB).
#Lumpectomy.
#Radical mastectomy.

Lumpectomies are usually oriented with short and long suture; '''s'''hort is typically '''s'''uperior (aspect) and '''l'''ong is typically '''l'''ateral (aspect).

Breast [[cytopathology]] is dealt with in the ''[[breast cytopathology]]'' article.  It is almost dead, as it is not as sensitive and specific as CNB.

Work-up of CNBs is dependent on the clinical abnormality:<ref>MUA. 1 October 2010.</ref>
#Mass lesion - usu. obvious what is going on; typically 3 levels.
#Calcifications - abnormality may be very small; typically 10 levels.

=Normal=
==Resting==
*Glands -- normally has two cell layers (like the [[prostate]]).
**Myoepithelial cells
***Frequently spindle-like, often hard to see.
**Secretory cells.
*Stroma:
**Not cellular.
**Not myxoid.

May be present:
*Calcification:
**Purple globs (with concentric rings) on H&E = calcium phosphate.
***Q. How to remember? A. '''P'''urple = '''P'''hosphate.
**Calcium oxalate visible with (light) polarization - not assoc. with malignancy.
**Often in the lumen of a gland, may be in the stroma.
**Calcific material typically has a well-demarcated border +/- "sharp corners".
**Radiologists can pick-up calcs (calcifications) that are approx. 100 micrometers; if "calcs" is on the requisition one needs to find calcs this size.<ref>MUA. 1 October 2010.</ref> 

Image:
*[http://www.breastpathology.info/Images/calcs/FatNec1_700.jpg Breast with calcifications (breastpathology.info)].

Notes:
*The architecture is more important than the cytologic features in the diagnosis of malignancy in the breast;<ref>RS. 4 May 2010.</ref> low grade tumours have distorted architecture but normal/near normal cytology.

==Lactational changes==
*[[AKA]] secretory change, [[AKA]] lactational adenoma.<ref>URL: [Breast_pathology#Lactational_changes Breast_pathology#Lactational_changes. Accessed on: 3 October 2011.</ref>
===General===
*May be present focally in non-pregnant females.

ASIDE:
*Some believe one ought ''lactational change'' and ''secretory change'' aren't the same...
**Lactationl change = only in lactation.
**Secretory change = other times.
*This hair splitting is clinically irrelevant-- both are benign.  Also, experts use the terms interchangeably.<ref name=pmid2879437>{{Cite journal  | last1 = Tavassoli | first1 = FA. | last2 = Yeh | first2 = IT. | title = Lactational and clear cell changes of the breast in nonlactating, nonpregnant women. | journal = Am J Clin Pathol | volume = 87 | issue = 1 | pages = 23-9 | month = Jan | year = 1987 | doi =  | PMID = 2879437 }}
</ref>

===Microscopic===
Features:<ref>URL: [http://flylib.com/books/en/2.953.1.9/1/ http://flylib.com/books/en/2.953.1.9/1/]. Accessed on: 6 August 2011.</ref>
*Glands dilated.
*Increased number of lobules.
**Relative decrease in intralobular and extralobular stroma.
*Luminal cells enlarged.
**Vacuolated cytoplasm.
**Hobnail morphology - hang into the lumen.
*Myoepithelial cells indistinct - after second trimester.

Images:
*[[WC]]:
**[http://commons.wikimedia.org/wiki/File:Lactational_change_-_low_mag.jpg Lactational change - low mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Lactational_change_-_high_mag.jpg Lactational change - high mag. (WC)].
*www:
**[http://www.gfmer.ch/selected_images_v2/detail_list.php?cat1=2&cat2=9&cat3=0&cat4=3&stype=n Lactational changes (gfmer.ch)].
**[http://www.webpathology.com/image.asp?case=320&n=7 Lactational changes in an angiosarcoma of the breast (webpathology.com)].
**[http://www.lab.anhb.uwa.edu.au/mb140/CorePages/FemaleRepro/femalerepro.htm#LabMamm Lactating breast (uwa.edu.au)].

=Where to start=
{{Main|Short_power_list#Breast_pathology|Long_power_list#Breast_pathology}}
The following entities are a starting point for understanding routine breast pathology & some of challenges in breast pathology:
#Apocrine change.
#*Pink benign cells.
#Columnar cell change.
#*Columnar cells with blebs ("snouts") - often have calcifications (purple).
#[[Fibroadenoma]].
#*Abundant myxoid (light/blanched) stroma - very common.
#[[Florid epithelial hyperplasia]].
#*Too many cells in a duct, cells overlap & form slit-like spaces.
#[[Ductal carcinoma in situ]] (DCIS).
#*Too many cells in a duct, nuclei do not touch - "cells are spaced".
#*Cells line-up around ovoid/circular spaces - "punch-out" appearance/"cookie cutter" look.
#*Myoepithelial cells present.
#Invasive ductal carcinoma.
#*Bread & butter cancer - in sheets or glands.
#[[Lobular carcinoma]].
#*Dyscohesive cells - can easily be missed.
#Tubular carcinoma.
#*Glands have one cell layer... but near normal appearance.

The key to breast pathology is... seeing the two cell layers (at low power).  The myoepithelial layer is hard to see at times and that is the challenge.

==Common diagnoses - overview==
*Normal.
*Benign.
**Columnar cell change. 
***Calcification often in lumen.
*Neoplastic.
**Benign neoplastic:
***Epithelial/myoepithelial - [[intraductal papilloma]].
***Stromal - fibroadenoma, benign phyllodes.
**Malignant neoplastic:
***Epithelial/myoepithelial - most common, e.g. ductal carcinoma, lobular carcinoma.
***Breast stroma - malignant phyllodes tumour.
***Stromal, e.g. [[angiosarcoma]] - quite rare.

==A tree diagram (overview)==
===General classification===
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BREAST PATHOLOGY - SIMPLE
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{{familytree | | | | B | | | | | X | | | | |C | | | | |B=Stromal<br>pathology|X=Miscellaneous|C=Glandular<br>pathology}}
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{{familytree | D | | | | E | | | | | F | | G | | H |D=Myxoid|E=Long slit-like<br>spaces|F=Simple<br>epithelium|G=Dilated|H=[[Breast pathology#Cellular lesions|Cellular lesions]]}}
{{familytree | |!| | | |,|-|^|-|.| | | | |!| | | |!| | | |!| |}}
{{familytree | I | | J | | K | | | L | | M | | N |I=[[Fibroadenoma]]|J=Malignant<br>features|K=Benign features|L=Tubular<br>carcinoma|M=[[FEA]], [[FCC]],<br>CCC|N=[[FEHUT]], Neoplastic,<br>Malignant}}
{{familytree | | | | | |!| | | |!| | | | | | | | | | | | | | |}}
{{familytree | | | | | O | | P | | | | | | | | | | | | | ||O=[[Phyllodes tumour|Malignant<br>phyllodes]]|P=[[Phyllodes tumour|Benign phyllodes]]}}
{{familytree/end}}

Notes:
*The challenges in breast pathology are in: the ''Simple epithelium'' category and the ''Cellular lesions'' category.
*''Neoplastic'' includes: ADH and LDH.
*''Malignant'' includes: DCIS, LCIS, ductal carcinoma (DC) and lobular carcinoma (LC), some papillary lesions.
*''Lobular carcinoma'' (a '''pitfall''') may appear to be a stromal problem, i.e. the stroma looks too cellular.
*''Miscellaneous'' includes rare tumours of the breast that do not fit into another category, i.e. [[metastases]], [[lymphoma]]s, [[melanoma]], sarcomas.  Skin-related pathology is dealt within the ''[[dermatologic neoplasms]]'' article. ''[[Paget disease of the breast]]'', which may be seen in the context of malignant breast lesions, is discussed in its own article.

===Cellular lesions===
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{{familytree | | | | | SP | | SS | | DE | | SF | | FC |SP=Equal spacing,<br>punched-out|SS=Streaming, periph. <br>slit-like spaces.|DE=Discohesive cells,<br>expanded gl.|SF=Single cells<br>or single file|FC=Fibrovascular<br>cores}}
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{{familytree | | | | | DL | | FEHUT | | LL | | LC | | PL |DL=Ductal lesion|FEHUT=[[FEHUT]]|LL=Lobular lesion|LC=[[Invasive lobular carcinoma|Lobular carcinoma]]|PL=[[Breast pathology#Papillary lesions|Papillary lesions]]}}
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{{familytree | | | DNI | | DC | | ALH | | LCIS | | | | | | |DNI=Ductal non-inv.<br>neoplasm|DC=[[Invasive ductal carcinoma of the breast|Ductal carcinoma]]|ALH=[[ALH]]|LCIS=[[LCIS]]}}
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{{familytree | LE | | SE | | | | | | | | | | | | | | | | |LE=Large extent|SE=Small extent}}
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{{familytree | DCIS | | ADH | | | | | | | | | | | | | | | | |DCIS=[[DCIS]]|ADH=[[ADH]]}}
{{familytree/end}}
Notes:
*The largest challenge is: differentiating between the first two categories on level 2, i.e. ''equal spacing' vs. ''streaming''.
*The ''fibrovascular cores'' must arise from a tuft, i.e. if they are arising directly from the wall of glands only it is likely ''papillary DCIS''.

===Papillary lesions===
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{{familytree | | | | | MP | | | | | | | | | |MA |MP=Myoepithelial cells<br>'''present'''|MA=Myoepithelial cells<br>'''absent'''}}
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{{familytree | D | | | | | | E | | | | | | F |D=Unremarkable<br>papillae|E=Atypia ''or'' arch. abnorm.<br>''or'' cellular proliferation|F=Neoplastic cells<br>present}}
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{{familytree | | | | | | | R | | S | | | | | | |R=DCIS in<br>papilloma|S=ADH in<br>papilloma}}
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Notes: 
*Adapted from ''Mulligan & O'Malley''.<ref>{{cite journal |author=Mulligan AM, O'Malley FP |title=Papillary lesions of the breast: a review |journal=Adv Anat Pathol |volume=14 |issue=2 |pages=108–19 |year=2007 |month=March |pmid=17471117 |doi=10.1097/PAP.0b013e318032508d |url=}}</ref>
*The most important decision is the first one: myoepithelial cells present vs. absent.
*''abnorm. arch.'' = abnormal architecture present.
*''DCIS'' = ductal carcinoma in situ.
*''FEHUT'' = florid epithelial hyperplasia of the usual type.
*''extent'' refers to the size of the abnormal cell population within the papillary lesion.

=Malignant lesions=
==Non-invasive breast cancer==
{{main|Non-invasive breast cancer}}
This includes the ''in situ'' lesions - ''DCIS'' and ''LCIS''.

==Invasive breast cancer==
{{main|Invasive breast cancer}} 
This is includes descriptions of the usual types... and the not so common ones.

=Common benign lesions=
The breast has lots of benign things.  Unlike the prostate, the where benign is called ''benign'', everything has a name.  It is more common among breast pathologists to sign-out things like: ''apocrine metaplasia'' (benign), ''columnar cell change'' (benign), and ''florid epithelial hyperplasia of the usual type (FEHUT)'' - instead of - ''benign breast tissue''.

==Mild epithelial hyperplasia==
===General===
*No increased risk of malignancy.
**Often ''not'' reported - as it has not clinical signficance.
*Has to be separated from ''[[moderate epithelial hyperplasia]]'' / ''[[florid epithelial hyperplasia]]''.

===Microscopic===
Features:<ref>{{Ref BP|159-160}}</ref>
*Breast glands with three ''or'' four cell layers above the basement membrane.
*Variable cells.

Note:
*No nuclear atypia.

DDx:
*[[Flat epithelial atypia]].
*[[Moderate epithelial hyperplasia]] / [[florid epithelial hyperplasia]].
*[[Atypical ductal hyperplasia]].

==Apocrine metaplasia==
===General===
*Benign/not significant.  Can be considered to be pretty wallpaper in the house of breast pathology.

====Etiology====
*Increased number of mitochondria.
**In other body sites this has different names, e.g. ''[[Hurthle cell change]]'' (thyroid), ''[[oncocytoma|oncocytic]] change'' (kidney - [[oncocytoma]], thyroid).

===Microscopic===
Features:
*Eosinophilic cytoplasm - '''key feature'''.

Note: 
*Apocrine changes, i.e. cytoplasmic eosinophilia, can appear in malignant tumours; eosinophilia doesn't make something benign.
*Apocrine snouts may be present. (???)
**Small globules at the apical aspect of the cell (composed of cytoplasm and plasma membrane).

Image:
*[http://commons.wikimedia.org/wiki/File:Fibrocystic_change_-_very_high_mag.jpg FCC with apocrine metaplasia (right bottom of image) - high mag. (WC)].

==Fibrocystic change==
*Abbreviated ''FCC''.
*[[AKA]] ''fibrocystic changes''.

===General===
*Really common.
*Benign.

===Microscopic===
Features:
*Dilated glands - '''key change'''.
**Glands normal: two cell layers present.
*Often seen together with ''apocrine metaplasia''.

Image:
*[[WC]]:
**[http://commons.wikimedia.org/wiki/File:Fibrocystic_change_-_intermed_mag.jpg FCC - intermed. mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Fibrocystic_change_-_very_high_mag.jpg FCC - high mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Phyllodes_tumour_-_very_low_mag.jpg FCC - left of image - and a phyllodes tumour - very low mag. (WC)].

==Columnar cell change==
*Abbreviated ''[[CCC]]''.
*[[AKA]] ''blunt duct adenosis''.
===General===
*Columnar cell change is associated with (benign) calcification - '''key point'''.

===Microscopic===
Features:
*Secretory cells (line gland lumen) have columnar morphology.
*May have "apical snouts". 
**Blebs or round balls eosinophilic material appear to be adjacent to the cell at their luminal surface.
**The snouts are attached to the cell-- appear as round ball only in the plane of section.
*Cytoplasm +/-eosinophilia.

DDx:
*Flat epithelial atypia (>2 cell layers).{{Fact}}

Image:
*[http://webpathology.com/image.asp?case=652&n=1 Columnar cell change (webpathology.com)].

==Gynecomastoid hyperplasia==
*[[AKA]] ''gynecomastia''.

===General===
*Benign enlargement of breasts in males.
**Histologic changes may be seen in females.<ref name=stony03>URL: [http://www.hsc.stonybrook.edu/breast-atlas/XIII-03.htm http://www.hsc.stonybrook.edu/breast-atlas/XIII-03.htm]. Accessed on: 16 November 2011.</ref>

May be seen in the context of: 
*[[Liver]] failure.
*[[Klinefelter syndrome]].
*Testicular estrogen-producing [[germ cell tumour]].  

===Microscopic===
Features:<ref name=stony03>URL: [http://www.hsc.stonybrook.edu/breast-atlas/XIII-03.htm http://www.hsc.stonybrook.edu/breast-atlas/XIII-03.htm]. Accessed on: 16 November 2011.</ref>
*Moderate hyperplasia.
**Glands have more than 2 cell layers.
*"Budding" - individual cells jut into the lumen - '''key feature'''.
*Stromal palor.<ref>URL: [http://radiology.uchc.edu/eAtlas/Breast/1693.htm http://radiology.uchc.edu/eAtlas/Breast/1693.htm]. Accessed on: 16 November 2011.</ref>

Images:
*www:
**[http://www.hsc.stonybrook.edu/breast-atlas/XIII-03.htm Gynecomastoid hyperplasia (stonybrook.edu)].
**[http://radiology.uchc.edu/eAtlas/Breast/1693.htm Gynecomastia (radiology.uchc.edu)].
*[[WC]]:
**[http://commons.wikimedia.org/wiki/File:Gynecomastoid_hyperplasia_-_intermed_mag.jpg Gynecomastoid hyperplasia - intermed. mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Gynecomastoid_hyperplasia_-_very_high_mag.jpg Gynecomastoid hyperplasia - very high mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Gynecomastoid_hyperplasia_-2-_intermed_mag.jpg Gynecomastoid hyperplasia - 2 - intermed. mag. (WC)].

=Lesions with increased risk of malignancy=

==Florid epithelial hyperplasia==
*[[AKA]] ''florid epithelial hyperplasia'', abbreviated ''FEH''.
*AKA ''florid epithelial hyperplasia of the usual type'', abbreviated ''FEHUT''.
*AKA ''epithelial hyperplasia'' - term should be avoid as it could lead to confusion with ''[[mild epithelial hyperplasia]]''.

===General===
*Mild increased risk of malignancy ~ 1.5-2x.<ref>{{Ref PCPBoD8|542}}</ref>
*Has to be separated from ''[[mild epithelial hyperplasia]]''.

Note:
*''Moderate epithelial hyperplasia'' redirects to this section.
**It is generally not separated from FEH, as the prognosis is thought to be the same.

===Microscopic===
Features:<ref>{{Ref BP|159-160}}</ref>
*Breast glands with ''more than'' four cell layers above the basement membrane - '''key feature'''.
*Irregular cell spacing; streaming.
*Slit-like lumina, esp. at the periphery of the duct.
*No [[DCIS]]-like architecture (not cribriform, not papillary, not micropapillary, not solid).
*No nuclear atypia - usu. not nucleoli.

Memory device ''CLEAN'': 
*'''C'''ell spacing is irregular, '''L'''umina are slit-like, '''E'''xtent is less than 2 mm or 2 ducts, '''A'''rchitecture ''not'' DCIS-like, '''N'''uclear atypia ''not'' present.

DDx:
*[[Mild epithelial hyperplasia]].
*[[Atypical ductal hyperplasia]].
*Cribriform [[ductal carcinoma in situ]]

==Sclerosing adenosis==
===General===
*Can be scary... can look like [[ductal carcinoma]].
*Derived from ''sclerosing''<ref>URL: [http://dictionary.reference.com/browse/sclerosis http://dictionary.reference.com/browse/sclerosis]. Accessed on: 16 March 2011.</ref> (hardening) and ''adenosis'' (glandular enlargement).
**Think ''scaring'' + ''lotsa glands'' and you're pretty close.

===Microscopic===
Features:
*Acini are smaller than usual and there are more of them.
**Acini often slit-like.
*Fibrosis (scleroses) - pink on H&E surrounds the acini. 
**Can mimic a [[dysmoplastic reaction]].

Notes:
*The acini should:
**Be in lobular arrangements, i.e. in groups (benign appearance at low power) - '''key feature'''.
**Have two cell layers like well-behaved breast glands do.

DDx:
*Low-grade ductal carcinoma.

==Flat epithelial atypia==
===General===
Epidemiology:
*Associated with ADH & DCIS; may represent a non-obligate precursor lesion of ADH & DCIS.<ref name=pmid18384213>{{Cite journal  | last1 = Lerwill | first1 = MF. | title = Flat epithelial atypia of the breast. | journal = Arch Pathol Lab Med | volume = 132 | issue = 4 | pages = 615-21 | month = Apr | year = 2008 | doi = 10.1043/1543-2165(2008)132[615:FEAOTB]2.0.CO;2 | PMID = 18384213 }}</ref>
*Low risk of progression to invasive malignancy.<ref name=pmid12927037>{{Cite journal  | last1 = Schnitt | first1 = SJ. | title = The diagnosis and management of pre-invasive breast disease: flat epithelial atypia--classification, pathologic features and clinical significance. | journal = Breast Cancer Res | volume = 5 | issue = 5 | pages = 263-8 | month =  | year = 2003 | doi = 10.1186/bcr625 | PMID = 12927037 }}</ref>

===Microscopic===
Features:
*"Flat" ~ three cells thick. (???)
*Hypercellular gland -- several layers.
*Columnar cell morphology.
*+/-Apical snouts.

DDx:
*[[Columnar cell change]].
*[[ADH]].
*Low grade [[DCIS]].

==Complex sclerosing lesion==
*[[AKA]] ''radial scar''.
===General===
**The term ''radial scar'' is a misnomer. It isn't a ''scar''. It isn't associated with prior trauma or surgery.<ref name=Ref_PBoD8_1072>{{Ref PBoD8|1072}}</ref>
*May appear malignant on imaging.<ref name=pmid11167596>{{cite journal |author=Ung OA, Lee WB, Greenberg ML, Bilous M |title=Complex sclerosing lesion: the lesion is complex, the management is straightforward |journal=ANZ J Surg |volume=71 |issue=1 |pages=35–40 |year=2001 |month=January |pmid=11167596 |doi= |url=}}</ref> 
*Associated with subsequent elevated risk of breast cancer.<ref>URL: [http://www.cancer.org/docroot/NWS/content/NWS_1_1x_Radial_Scars.asp http://www.cancer.org/docroot/NWS/content/NWS_1_1x_Radial_Scars.asp]. Accessed on: 4 May 2010.</ref>
*Management - usu. surgical excision.<ref name=pmid14514771>{{cite journal |author=Kennedy M, Masterson AV, Kerin M, Flanagan F |title=Pathology and clinical relevance of radial scars: a review |journal=J. Clin. Pathol. |volume=56 |issue=10 |pages=721–4 |year=2003 |month=October |pmid=14514771 |pmc=1770086 |doi= |url=}}</ref> 
===Gross===
*Spiculated mass.
*Usually small - 3-7 mm.

Image: 
*[http://commons.wikimedia.org/wiki/File:Radial_scar.jpg Radial scar - gross (WC)].

===Microscopic===
Features:<ref name=pmid14514771>{{cite journal |author=Kennedy M, Masterson AV, Kerin M, Flanagan F |title=Pathology and clinical relevance of radial scars: a review |journal=J. Clin. Pathol. |volume=56 |issue=10 |pages=721–4 |year=2003 |month=October |pmid=14514771 |pmc=1770086 |doi= |url=}}</ref><ref name=Ref_BP91>{{Ref BP|91}}</ref>
*Stellate appearance (low magnification).
*Center of lesion has "fibroelastosis" - stroma light pink (on H&E) - '''key feature'''.
**Scar like stroma with entrapped normal breast ducts and lobules.
**Glands appear to enlarge with distance from center of lesion.

Image: [http://www.breastpathology.info/Images/Benign/Radial_scar/rs3a_700.jpg Radial scar (breastpathology.info)].

Notes:
*Histomorphologic appearance may mimic a desmoplastic reaction of stroma - leading to a misdiagnosis of malignancy.
*"[[Hyaline]] - pink stuff on H&E - is the key."<ref>RS. May 2010.</ref>

=Stromal lesions=
This section (below) covers stromal lesions of the breast, which vary from benign to malignant.  The most common is (the benign) [[fibroadenoma]].  

Non-breast stroma stromal lesions are covered in the ''[[soft tissue lesions]]'' article.  [[Angiosarcoma]] (dealt with in the ''[[vascular tumours]]'' article) is the most common (non-breast stroma) sarcoma of the breast, and classically arises after treatment for a breast carcinoma.

==Fibroadenoma==
===General===
*Very common benign finding.
*The pathology is in the stroma; so, the lesion is really a misnomer by the naming rules. 
**It ought to be called ''adenofibroma'' (as a few occasionally do)<ref name=pmid15797289>{{Cite journal  | last1 = Guinebretière | first1 = JM. | last2 = Menet | first2 = E. | last3 = Tardivon | first3 = A. | last4 = Cherel | first4 = P. | last5 = Vanel | first5 = D. | title = Normal and pathological breast, the histological basis. | journal = Eur J Radiol | volume = 54 | issue = 1 | pages = 6-14 | month = Apr | year = 2005 | doi = 10.1016/j.ejrad.2004.11.020 | PMID = 15797289 }}</ref>, as the glandular component is benign and the stromal component lesional.

Management:
*Local excision -- without a large margin.

===Gross===
Features:<ref>{{Ref PCPBoD8|550}}</ref>
*Well-circumscribed.
*Rubbery - '''classic descriptor'''.
*Tan/white.
*+/-Lobulated appearance.
*+/-Slit-like spaces - short.
*+/-Calcification.

Images:
*[http://webpathology.com/image.asp?n=2&Case=276 Fibroadenoma - slit-like spaces (webpathology.com)].
*[http://webpathology.com/image.asp?case=276&n=3 Fibroadenoma - lobulated appearance (webpathology.com)].
*[http://www.surgical-tutor.org.uk/default-home.htm?tutorials/fibroadenoma.htm~right Fibroadenoma (surgical-tutor.org)].

===Microscopic===
Features:<ref name=Ref_BP110>{{Ref BP|110}}</ref>
*Abundant (intralobular) stroma - most '''key feature'''.
**Stroma is usually:
***White/pale, i.e. [[myxoid stroma|myxoid]], on H&E (normal stroma is pink).
****May be hyalinized (dark pink) if infarcted.
***Paucicellular - typical.
*Compression of glandular elements - very commonly seen.
**Glandular elements have at least two cell layers - epithelial and myoepithelial.

Notes:
#There is stuff about ''intracanalicular'' vs. ''pericanalicular''.<ref>URL: [http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970216-9 http://www.pathconsultddx.com/pathCon/diagnosis?pii=S1559-8675%2806%2970216-9]. Accessed on: 16 March 2011.</ref>  It is irrelevant; there is no prognostic difference between the two.
#Do '''not''' comment on the margin - it is irrelevant.

DDx:
*[[Phyllodes tumour]] - long slit-like spaces (seen grossly), stroma is more cellular.
**+/-Mitoses, 
**+/-"Stromal overgrowth" = large area where there is a 'loss of glands'.
*Sarcoma.
*[[Pseudoangiomatous stromal hyperplasia]].
**Small capillary-like structures in the stroma.
***Epithelial component often not compressed - as in fibroadenoma.


Images:
*[http://radiographics.rsna.org/content/27/suppl_1/S101/F40.expansion.html Infarcted fibroadenoma (rsna.org)].<ref name=pmid18180221>{{Cite journal  | last1 = Sabate | first1 = JM. | last2 = Clotet | first2 = M. | last3 = Torrubia | first3 = S. | last4 = Gomez | first4 = A. | last5 = Guerrero | first5 = R. | last6 = de las Heras | first6 = P. | last7 = Lerma | first7 = E. | title = Radiologic evaluation of breast disorders related to pregnancy and lactation. | journal = Radiographics | volume = 27 Suppl 1 | issue =  | pages = S101-24 | month = Oct | year = 2007 | doi = 10.1148/rg.27si075505 | PMID = 18180221 }}</ref>
*[http://www.imagingpathways.health.wa.gov.au/includes/images/image/fibroadenoma_he.jpg Fibroadenoma (gov.au)].<ref>URL: [http://www.imagingpathways.health.wa.gov.au/includes/dipmenu/image/image.html http://www.imagingpathways.health.wa.gov.au/includes/dipmenu/image/image.html]. Accessed on: 15 February 2012.</ref>

====Variants====
Four variants are described by the ''Washington Manual'':<ref name=Ref_WMSP262>{{Ref WMSP|262}}</ref>
#Juvenile.
#Complex.
#Myxoid.
#Cellular.

Considered a variant of fibroadenoma by many authorities:<ref name=Ref_BP116>{{Ref BP|116}}</ref>
*''[[Tubular adenoma of the breast]]''. 

=====Juvenile fibroadenoma=====
*As the name suggests, is typically found in younger patients.
*Classic history: rapid growth.

Features (juvenile variant):<ref>URL: [http://www.breastpathology.info/fibro_variants.html#juvenile http://www.breastpathology.info/fibro_variants.html#juvenile]. Accessed on: 3 October 2011.</ref>
*Stromal and epithelial hyperplasia - '''key feature'''.
*+/-Tapering, thin micropapillae (''[[gynecomastoid hyperplasia]]'').<ref name=Ref_BP116>{{Ref BP|116}}</ref>
*Mitoses uncommon.

=====Myxoid fibroadenoma=====
*May be associated with ''[[Carney's complex]]''.

Features:
*[[Myxoid stroma]].

=====Cellular fibroadenoma=====
Features (cellular variant):
*Cellular.
*Mitoses.

=====Complex fibroadenoma=====
*Contain proliferative epithelium which outside and inside a fibroadenoma is associated with an increased risk of malignancy.

Features:<ref>URL: [http://www.breastpathology.info/fibro_variants.html#complex http://www.breastpathology.info/fibro_variants.html#complex]. Accessed on: 3 October 2011.</ref>
# [[Apocrine metaplasia]].
# Cysts > 3 mm.
# Calcification.
# [[Sclerosing adenosis]].

Memory devices:
*''FACS'': complex '''f'''ibroadenoma, '''a'''pocrine metaplasia, '''c'''alcs''' & '''c'''ysts, ''', '''s'''clerosing adenosis.
*''CAMS'': '''c'''alcs, '''a'''pocrine metaplasia, '''m'''icrocysts, '''s'''clerosing adenosis.

=====Tubular adenoma of the breast=====
*Considered by many a variant of ''fibroadenoma''.
**[[IHC]] features of ''tubular adenoma of the breast'' and ''fibroadenoma'' are similar.<ref>{{Cite journal  | last1 = Maiorano | first1 = E. | last2 = Albrizio | first2 = M. | title = Tubular adenoma of the breast: an immunohistochemical study of ten cases. | journal = Pathol Res Pract | volume = 191 | issue = 12 | pages = 1222-30 | month = Dec | year = 1995 | doi =  | PMID = 8927570 }}</ref>

Features:<ref name=Ref_BP116>{{Ref BP|116}}</ref>
*Fibromyxoid stroma (like in a fibroadenoma).
*Small round glands.

Image:
*[http://www.webpathology.com/image.asp?case=277&n=1 Tubular adenoma of the breast (webpathology.com)].

==Phyllodes tumour==
The name comes from the word "leaf"; with imagination or psychotropic drugs, it may look like one (the epithelial component = the veins of the leaf).

===General===
*Wide excision -- this differs from fibroadenoma (just local excision).
*Approximately 6% are malignant.<ref name=pmid12689668>{{cite journal |author=Guerrero MA, Ballard BR, Grau AM |title=Malignant phyllodes tumor of the breast: review of the literature and case report of stromal overgrowth |journal=Surg Oncol |volume=12 |issue=1 |pages=27–37 |year=2003 |month=July |pmid=12689668 |doi= |url=http://linkinghub.elsevier.com/retrieve/pii/S0960740403000057}}</ref>

===Gross===
*Clefts/leaf-like structures.
*Friable - esp. vis-a-vis a [[fibroadenoma]].

Image:
*[http://radiographics.rsna.org/content/29/3/907/F48.expansion.html Benign phyllodes tumour (rsna.org)].

===Microscopic===
Features:
*Large slit-like spaces.
*Cellular stroma that may be [[myxoid stroma|myxoid]].
*+/-Mitoses.
*May have "malignant border" -- "pushing border" / "infiltrative border".

Image:
*[http://en.wikipedia.org/wiki/File:Phyllodes_tumour_-_very_low_mag.jpg Phyllodes tumour - very low mag. (WC)].
*[http://en.wikipedia.org/wiki/File:Phyllodes_tumour_-_low_mag.jpg Phyllodes tumour - low mag. (WC)].

====Malignant phyllodes?====
Features of malignancy:<ref name=pmid17932112>{{cite journal |author=Taira N, Takabatake D, Aogi K, ''et al'' |title=Phyllodes tumor of the breast: stromal overgrowth and histological classification are useful prognosis-predictive factors for local recurrence in patients with a positive surgical margin |journal=Jpn. J. Clin. Oncol. |volume=37 |issue=10 |pages=730-6 |year=2007 |month=October |pmid=17932112 |doi=10.1093/jjco/hym099 |url=http://jjco.oxfordjournals.org/cgi/reprint/37/10/730}}</ref>
*Stromal cellular atypia.
*Mitotic activity in 10 [[HPF]]s.
**"HPF" is not adequately defined - see [[HPFitis]]. The authors should be spanked.
*Stromal overgrowth -- epithelial elements absent in one low power field (x40).<ref name=pmid17932112/>
**"LPF" is not adequately defined - see [[LPFitis]]. The authors should be spanked.


A comparison between benign and malignant phyllodes - adapted from Taira et al.<ref name=pmid17932112/>
{| class="wikitable"
|			|| '''Benign'''	|| '''Malignant'''
|-
|Stromal overgrowth	|| no		|| yes
|-
|Mitoses		|| >4/10 [[HPF]]	|| >=10/10 HPF
|-
|Atypia of stromal cells || <= moderate	|| marked
|-
|}

See also: [[Phyllodes tumour vs. fibroadenoma]].

==Pseudoangiomatous stromal hyperplasia==
*Abbreviated ''PASH''.
*[[AKA]] ''nodular myofibroblastic stromal hyperplasia of the mammary gland''.<ref name=pmid12199757>{{Cite journal  | last1 = Leon | first1 = ME. | last2 = Leon | first2 = MA. | last3 = Ahuja | first3 = J. | last4 = Garcia | first4 = FU. | title = Nodular myofibroblastic stromal hyperplasia of the mammary gland as an accurate name for pseudoangiomatous stromal hyperplasia of the mammary gland. | journal = Breast J | volume = 8 | issue = 5 | pages = 290-3 | month =  | year =  | doi =  | PMID = 12199757 }}</ref>

===General===
*Benign lesion.
*Thought to arise due to myofibroblast abnormality - though not well understood.<ref name=pmid7872425>{{cite journal |author=Powell CM, Cranor ML, Rosen PP |title=Pseudoangiomatous stromal hyperplasia (PASH). A mammary stromal tumor with myofibroblastic differentiation |journal=Am. J. Surg. Pathol. |volume=19 |issue=3 |pages=270–7 |year=1995 |month=March |pmid=7872425 |doi= |url=}}</ref> 

===Gross===
Features:<ref name=pmid7872425>{{cite journal |author=Powell CM, Cranor ML, Rosen PP |title=Pseudoangiomatous stromal hyperplasia (PASH). A mammary stromal tumor with myofibroblastic differentiation |journal=Am. J. Surg. Pathol. |volume=19 |issue=3 |pages=270–7 |year=1995 |month=March |pmid=7872425 |doi= |url=}}</ref>
*May form mass: grey-white & firm, with well circumscribed borders.

===Microscopic===
Features:<ref name=pmid3949338>{{cite journal |author=Vuitch MF, Rosen PP, Erlandson RA |title=Pseudoangiomatous hyperplasia of mammary stroma |journal=Hum. Pathol. |volume=17 |issue=2 |pages=185–91 |year=1986 |month=February |pmid=3949338 |doi= |url=}}</ref><ref name=pmid18084246>{{Cite journal  | last1 = Ferreira | first1 = M. | last2 = Albarracin | first2 = CT. | last3 = Resetkova | first3 = E. | title = Pseudoangiomatous stromal hyperplasia tumor: a clinical, radiologic and pathologic study of 26 cases. | journal = Mod Pathol | volume = 21 | issue = 2 | pages = 201-7 | month = Feb | year = 2008 | doi = 10.1038/modpathol.3801003 | PMID = 18084246 }}</ref>
*Abundant breast stromal.
*Small, complex, inter-anastomosing (blood vessel/capillary-like) channels - '''key feature'''.
**''Pseudoangiomatous'' = blood vessel-like.

Notes:
*May mimic angiosarcoma at low power; PASH may have the same architecture but lack nuclear atypia.

DDx:
*[[Angiosarcoma]].
*[[Fibroadenoma]].

Images:
*[http://commons.wikimedia.org/wiki/File:Pseudoangiomatous_stromal_hyperplasia_-a-_low_mag.jpg PASH - low mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Pseudoangiomatous_stromal_hyperplasia_-a-_intermed_mag.jpg PASH - intermed. mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Pseudoangiomatous_stromal_hyperplasia_-_high_mag.jpg PASH - high mag. (WC)].
*[http://www.nature.com/modpathol/journal/v21/n2/fig_tab/3801003f1.html#figure-title PASH (nature.com)].<ref name=pmid18084246>{{Cite journal  | last1 = Ferreira | first1 = M. | last2 = Albarracin | first2 = CT. | last3 = Resetkova | first3 = E. | title = Pseudoangiomatous stromal hyperplasia tumor: a clinical, radiologic and pathologic study of 26 cases. | journal = Mod Pathol | volume = 21 | issue = 2 | pages = 201-7 | month = Feb | year = 2008 | doi = 10.1038/modpathol.3801003 | PMID = 18084246 }}</ref>

===IHC===
Findings:<ref name=pmid7872425/>
*CD34 +ve.
*Vimentin +ve.
*Factor VIII -ve.

=Weird stuff=
Like in all niches of pathology... there is weird stuff.

==Mammary hamartoma==
*[[AKA]] ''breast hamartoma''.
===General===
*Benign.
*Disordered growth - see ''[[hamartoma]]''.

===Gross===
*Well-circumscribed - '''key feature'''.

===Microscopic===
Features:<ref name=Ref_BP117>{{Ref BP|117}}</ref>
*Disordered arrangement of ductal and lobular structures.
*Normal arrangement of cells with in the ductal structures, i.e. myoepithelium and epithelium present.
*Variable features:<ref name=surgpath_stan>URL: [http://surgpathcriteria.stanford.edu/breast/mammhamart/ http://surgpathcriteria.stanford.edu/breast/mammhamart/]. Accessed on: 4 October 2011.</ref>
*#Adipose tissue - predominant.
*#Dense fibrosis tissue - predominant.
*#Cystic glandular dilation.

Notes:
*If adipose tissue predominates; it may be labeled ''adenolipoma''.<ref name=surgpath_stan>URL: [http://surgpathcriteria.stanford.edu/breast/mammhamart/ http://surgpathcriteria.stanford.edu/breast/mammhamart/]. Accessed on: 4 October 2011.</ref>

DDx:
*[[Fibroadenoma]].
*[[Phyllodes tumour]].
*[[Pseudoangiomatous stromal hyperplasia]].
*[[Fibrocystic changes]].

Images:
*[http://www.breastpathology.info/sub-pages-iotw/2008/18.html Mammary hamartoma (breastpathology.info)].
*[http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1769817/figure/f2/ Mammary hamartoma (nih.gov)].<ref name=pmid12461066>{{Cite journal  | last1 = Tse | first1 = GM. | last2 = Law | first2 = BK. | last3 = Ma | first3 = TK. | last4 = Chan | first4 = AB. | last5 = Pang | first5 = LM. | last6 = Chu | first6 = WC. | last7 = Cheung | first7 = HS. | title = Hamartoma of the breast: a clinicopathological review. | journal = J Clin Pathol | volume = 55 | issue = 12 | pages = 951-4 | month = Dec | year = 2002 | doi =  | PMID = 12461066 | PMC = 1769817 | URL = http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1769817/}}</ref>
===IHC===
*None - it's a [[H&E]] diagnosis.

==Collagenous spherulosis==
*[[AKA]] ''mucinous spherulosis'', [[AKA]] ''spherulosis''.<ref name=stanford_collspher>URL: [http://surgpathcriteria.stanford.edu/breast/collspher/ http://surgpathcriteria.stanford.edu/breast/collspher/]. Accessed on: 4 September 2011.</ref>
===General===
*Benign.
*Almost always an incidental finding.
*Can mimic [[ADH]], cribriform [[DCIS]], [[adenoid cystic carcinoma]].<ref name=pmid16330938>{{Cite journal  | last1 = Resetkova | first1 = E. | last2 = Albarracin | first2 = C. | last3 = Sneige | first3 = N. | title = Collagenous spherulosis of breast: morphologic study of 59 cases and review of the literature. | journal = Am J Surg Pathol | volume = 30 | issue = 1 | pages = 20-7 | month = Jan | year = 2006 | doi =  | PMID = 16330938 }}</ref>
**Epidemiologically, it may be associated with [[LCIS]].<ref name=pmid16330938/>

===Microscopic===
Features:<ref name=stanford_collspher>URL: [http://surgpathcriteria.stanford.edu/breast/collspher/ http://surgpathcriteria.stanford.edu/breast/collspher/]. Accessed on: 4 September 2011.</ref><ref>URL: [http://www.hsc.stonybrook.edu/breast-atlas/V-33.htm http://www.hsc.stonybrook.edu/breast-atlas/V-33.htm]. Accessed on: 31 August 2011.</ref>
*Tubular/cribriform architecture.
*Intratubular eosinophilic material - '''key feature'''.
**Classical: Arranged like the spokes of a wheel ("radial spikes").
**Atypical: Granules ~ 1-2 micrometers.
*No mitotic activity.
*Two cells populations (epithelial & myoepithelial) - like a well-behaved breast gland.

Notes:
*Usually small lesions: < 50 spherules per lesion, <100 micrometers.
*May be multifocal.
*+/-Calcifications - may prompt biopsy.

Images:
*[[WC]]:
**[http://commons.wikimedia.org/wiki/File:Collagenous_spherulosis_-_intermed_mag.jpg Collagenous spherulosis - intermed. mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Collagenous_spherulosis_-_very_high_mag.jpg Collagenous spherulosis - very high mag. (WC)].
*www:
**[http://www.hsc.stonybrook.edu/breast-atlas/V-33.htm Collagenous spherulosis (stonybrook.edu)].

==Nipple adenoma==
*[[AKA]] ''nipple duct adenoma'', ''nipple adenoma of breast'', ''adenoma of the nipple''.

===General===
*Rare.

Clinical DDx:
*[[Paget's disease of the breast]].<ref name=pmid13904317>{{Cite journal  | last1 = HANDLEY | first1 = RS. | last2 = THACKRAY | first2 = AC. | title = Adenoma of nipple. | journal = Br J Cancer | volume = 16 | issue =  | pages = 187-94 | month = Jun | year = 1962 | doi =  | PMID = 13904317 | PMC = 2070922 | url = http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2070922/?tool=pubmed  }}</ref>

===Microscopic===
Features:
*Proliferation of epithelial and myoepithelial elements that extends into the breast stroma.<ref name=pmid2123505>{{Cite journal  | title = Adenoma of Nipple. | journal = Br Med J | volume = 1 | issue = 5330 | pages = 563 | month = Mar | year = 1963 | doi =  | PMID = 20789667 | PMC = 2123505 | url = http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2123505/?page=1 }}</ref>

Notes:
*Not encapsulated.<ref name=pmid2123505/>
*Lacks true fibrovascular cores.<ref>URL: [http://surgpathcriteria.stanford.edu/breast/nippleadenoma/printable.html http://surgpathcriteria.stanford.edu/breast/nippleadenoma/printable.html]. Accessed on: 6 August 2011.</ref>

DDx:
*[[Intraductal papilloma]].
**Found within the duct '''not''' the stroma.
**Often deeper. (???)

Images:
*[http://commons.wikimedia.org/wiki/File:Nipple_adenoma_-_low_mag.jpg Nipple adenoma - low mag. (WC)].
*[http://commons.wikimedia.org/wiki/File:Nipple_adenoma_-_very_high_mag.jpg  Nipple adenoma - very high mag. (WC)].

==Intraductal papilloma==
*[[AKA]] ''papilloma''.
===General===
*May cause nipple discharge.<ref>{{Cite journal  | last1 = Zervoudis | first1 = S. | last2 = Iatrakis | first2 = G. | last3 = Economides | first3 = P. | last4 = Polyzos | first4 = D. | last5 = Navrozoglou | first5 = I. | title = Nipple discharge screening. | journal = Womens Health (Lond Engl) | volume = 6 | issue = 1 | pages = 135-51 | month = Jan | year = 2010 | doi = 10.2217/whe.09.81 | PMID = 20050819 }}</ref>
*Similar to ''[[papillary hidradenoma]]'' of the [[vulva]].

===Microscopic===
Features:
*True papillae - nipple-shaped structures with fibrovascular cores.
*Intraductal proliferation of epithelial and myoepithelial elements.<ref name=pmid2123505>{{Cite journal  | title = Adenoma of Nipple. | journal = Br Med J | volume = 1 | issue = 5330 | pages = 563 | month = Mar | year = 1963 | doi =  | PMID = 20789667 | PMC = 2123505 | url = http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2123505/?page=1 }}</ref>

Notes:
*Lacks florid hyperplasia.<ref>URL: [http://surgpathcriteria.stanford.edu/breast/nippleadenoma/printable.html http://surgpathcriteria.stanford.edu/breast/nippleadenoma/printable.html]. Accessed on: 6 August 2011.</ref>
*May degeneration and hyalinize to form a ''sclerosing papilloma''.

DDx:
*Intraductal papilloma with [[florid epithelial hyperplasia]].
*Intraductal papilloma with [[atypical ductal hyperplasia]]. †
*Intraductal papilloma with [[ductal carcinoma in situ]]. †

† Size criteria are different in papillomas.

Images:
*[[WC]]:
**[http://commons.wikimedia.org/wiki/File:Papillary_hidradenoma_-_low_mag.jpg Papillary hidradenoma - low mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Papillary_hidradenoma_-_very_high_mag.jpg Papillary hidradenoma - very high mag. (WC)].

==Diabetic mastopathy==
===General===
*[[Diabetes mellitus]] (DM).
**If DM is absent it is called ''lymphocytic mastitis''.<ref name=pmid12640102>{{Cite journal  | last1 = Valdez | first1 = R. | last2 = Thorson | first2 = J. | last3 = Finn | first3 = WG. | last4 = Schnitzer | first4 = B. | last5 = Kleer | first5 = CG. | title = Lymphocytic mastitis and diabetic mastopathy: a molecular, immunophenotypic, and clinicopathologic evaluation of 11 cases. | journal = Mod Pathol | volume = 16 | issue = 3 | pages = 223-8 | month = Mar | year = 2003 | doi = 10.1097/01.MP.0000056627.21128.74 | PMID = 12640102 }}</ref>
*Rare.

===Microscopic===
Features:<ref>URL: [http://www.breastpathology.info/Case_of_the_month/2007/COTM_0707%20discussion.html http://www.breastpathology.info/Case_of_the_month/2007/COTM_0707%20discussion.html]. Accessed on: 28 November 2010.</ref>
* Stromal collagen with keloid-like changes.
* Lymphocytic infiltrates:
** Lobules.
** Perivascular.
* Enlarged stromal fibroblasts.

DDx:
*Primary lymphoma of the breast.

===IHC===
*B cell predominant (CD20 > CD3).<ref name=pmid12640102/>
**B cells CD43 -ve.

===Molecular===
*Negative clonality studies.

==Microglandular adenosis==
*Abbreviated ''MGA''.
===General===
*Controversial thingy.

===Microscopic===
Features:<ref name=uscap_mga>URL: [http://www.uscap.org/site~/iap2006/slides08-4v.htm http://www.uscap.org/site~/iap2006/slides08-4v.htm]. Accessed on: 18 May 2011.</ref>
*Round glands lined by a single layer of cells.
*May extend into fat.

DDx:
*[[Tubular carcinoma]] - has apical snouts, desmoplasia among other things; see page by ''Collins''.<ref name=uscap_mga>URL: [http://www.uscap.org/site~/iap2006/slides08-4v.htm http://www.uscap.org/site~/iap2006/slides08-4v.htm]. Accessed on: 18 May 2011.</ref>
*[[Sclerosing adenosis]].

Images:
*[http://www.surgicalpathologyatlas.com/glfusion/mediagallery/media.php?f=1&s=20080802171452955&i=0&p=0 Microglandular adenosis (surgical pathologyatlas.com)].
*[http://webpathology.com/image.asp?n=1&Case=282 MGA - low mag. (webpathology.com)].
*[http://webpathology.com/image.asp?n=2&Case=282 MGA - high mag. (webpathology.com)].
*[http://www.breastpathology.info/Images/Benign/SclerAdenosis/mga1c_400.jpg MGA (breastpathology.info)].
*[http://www.breastpathology.info/sub-pages-iotw/2010/2.html MGA - several images (breastpathology.info)].

===IHC===
Features:<ref name=pmid8821958>{{Cite journal  | last1 = Joshi | first1 = MG. | last2 = Lee | first2 = AK. | last3 = Pedersen | first3 = CA. | last4 = Schnitt | first4 = S. | last5 = Camus | first5 = MG. | last6 = Hughes | first6 = KS. | title = The role of immunocytochemical markers in the differential diagnosis of proliferative and neoplastic lesions of the breast. | journal = Mod Pathol | volume = 9 | issue = 1 | pages = 57-62 | month = Jan | year = 1996 | doi =  | PMID = 8821958 }}</ref>
*S100 +ve.
*34BE12 +ve -- focal!

==Adenomyoepithelioma==
===General===
*Rare lesion consisting of epithelial and myoepithelial elements.
**May occur in other sites, e.g. tonsil.<ref name=pmid20356364>{{Cite journal  | last1 = Ren | first1 = J. | last2 = Song | first2 = L. | last3 = Dang | first3 = Q. | last4 = Zhang | first4 = X. | last5 = Jiang | first5 = SW. | last6 = Zhang | first6 = G. | last7 = Wang | first7 = N. | last8 = Liu | first8 = Z. | last9 = Wang | first9 = J. | title = Primary adenomyoepithelioma of tonsil. | journal = Head Neck Oncol | volume = 2 | issue =  | pages = 7 | month =  | year = 2010 | doi = 10.1186/1758-3284-2-7 | PMID = 20356364 }}</ref>
*May be benign or malignant.<ref name=pmid12591699>{{Cite journal  | last1 = Howlett | first1 = DC. | last2 = Mason | first2 = CH. | last3 = Biswas | first3 = S. | last4 = Sangle | first4 = PD. | last5 = Rubin | first5 = G. | last6 = Allan | first6 = SM. | title = Adenomyoepithelioma of the breast: spectrum of disease with associated imaging and pathology. | journal = AJR Am J Roentgenol | volume = 180 | issue = 3 | pages = 799-803 | month = Mar | year = 2003 | doi =  | PMID = 12591699 | url=http://www.ajronline.org/content/180/3/799.full}}</ref><ref name=pmid19480267>{{Cite journal  | last1 = Zizi-Sermpetzoglou | first1 = A. | last2 = Vasilakaki | first2 = T. | last3 = Grammatoglou | first3 = X. | last4 = Petrakopoulou | first4 = N. | last5 = Nikolaidou | first5 = ME. | last6 = Glava | first6 = C. | title = Malignant adenomyoepithelioma of the breast--case report. | journal = Eur J Gynaecol Oncol | volume = 30 | issue = 2 | pages = 234-6 | month =  | year = 2009 | doi =  | PMID = 19480267 }}</ref>

Note:
*Possibly the same tumour as [[epithelial-myoepithelial carcinoma]] of the [[salivary gland]].<ref name=pmid9769134>{{Cite journal  | last1 = Seifert | first1 = G. | title = Are adenomyoepithelioma of the breast and epithelial-myoepithelial carcinoma of the salivary glands identical tumours? | journal = Virchows Arch | volume = 433 | issue = 3 | pages = 285-8 | month = Sep | year = 1998 | doi =  | PMID = 9769134 }}</ref>

===Microscopic===
Features:<ref>URL: [http://www.webpathology.com/image.asp?n=1&Case=322 http://www.webpathology.com/image.asp?n=1&Case=322]. Accessed on: 16 August 2011.</ref>
*Well-circumscribed.
*Glandular architecture with:
**Easily identifiable myoepithelial cells - with clear cytoplasm - '''key feature'''.
**Eosinophilic cuboidal epithelial cells.
*Eosinophilic basement membrane material between glands.

DDx:
*Invasive ductal carcinoma (on core biopsy).
*Mammary pleomorphic adenoma.
*Ductal adenoma.

Images:
*Webpathology.com:
**[http://www.webpathology.com/image.asp?n=1&Case=322 Adenomyoepithelioma - low mag. (webpathology.com)].
**[http://www.webpathology.com/image.asp?n=4&Case=322 Adenomyoepithelioma - high mag. (webpathology.com)].
*WC:
**[http://commons.wikimedia.org/wiki/File:Adenomyoepithelioma_-_low_mag.jpg Adenomyoepithelioma - low mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Adenomyoepithelioma_-_high_mag.jpg Adenomyoepithelioma - high mag. (WC)].

==Mammary myofibroblastoma==
===General===
*Rare.
*Excision = cure.

Note:
*In extra-mammary sites the tumour is known as a ''mammary-type myofibroblastoma'' may immunohistochemically and histomorphologically overlap with [[spindle cell lipoma]].<ref name=pmid11474286>{{Cite journal  | last1 = McMenamin | first1 = ME. | last2 = Fletcher | first2 = CD. | title = Mammary-type myofibroblastoma of soft tissue: a tumor closely related to spindle cell lipoma. | journal = Am J Surg Pathol | volume = 25 | issue = 8 | pages = 1022-9 | month = Aug | year = 2001 | doi =  | PMID = 11474286 }}</ref>

===Microscopic===
Features:<ref name=Ref_BP131>{{Ref BP|131}}</ref>
*Well-circumscribed lesion.
*Spindle cells without nuclear atypia arranged in fascicles.
*Interspersed thick bundles of collagen.

Notes:
*No calcifications.
*No necrosis.
*No hemorrhage.

DDx:
*[[Metaplastic breast carcinoma]].
*Fibromatosis.
*[[Leiomyoma]] of the breast.
*[[Nodular fasciitis]].
*[[Phyllodes tumour]].

Images:
*[[WC]]:
**[http://commons.wikimedia.org/wiki/File:Mammary_myofibroblastoma_-_low_mag.jpg Mammary myofibroblastoma - low mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Mammary_myofibroblastoma_-_intermed_mag.jpg Mammary myofibroblastoma - intermed. mag. (WC)].
**[http://commons.wikimedia.org/wiki/File:Mammary_myofibroblastoma_-_high_mag.jpg Mammary myofibroblastoma - high mag. (WC)].
*www:
**[http://path.upmc.edu/cases/case249.html Mammary myofibroblastoma - several images (upmc.edu)].

===IHC===
Features:<ref name=pmid22096693>{{Cite journal  | last1 = Mele | first1 = M. | last2 = Jensen | first2 = V. | last3 = Wronecki | first3 = A. | last4 = Lelkaitis | first4 = G. | title = Myofibroblastoma of the breast: Case report and literature review. | journal = Int J Surg Case Rep | volume = 2 | issue = 6 | pages = 93-6 | month =  | year = 2011 | doi = 10.1016/j.ijscr.2011.02.006 | PMID = 22096693 }}</ref>
*CD34 +ve.<ref name=pmid11474286/>
*Desmin +ve.<ref name=pmid11474286/>
*H-caldesmon +ve.
*Actin +ve.
*Vimentin +ve.

Other
*S100 -ve.
*Beta-catenin -ve. (???)

==Squamous metaplasia of lactiferous ducts==
*Abbreviated ''SMOLD''.
===General===
*Post-menopausal women.
*May be associated with subareolar abscess.

===Microscopic===
Features:
*Replacement of bilayer in lactiferous ducts with squamous epithelium.
*Xanthomatous reaction.

=See also=
*[[Breast cytopathology]].
*[[Salivary gland]].
*[[Invasive breast cancer]].
*[[Non-invasive breast cancer]].

=References=
{{reflist|2}}

[[Category:Breast pathology]]

=External links=
*[http://www.breastpathology.info/Case_of_the_month/cotm_root.html A collection of breast pathology cases (breastpathology.info)].
*[http://www.webpathology.com/atlas_map.asp?section=9 Breast pathology (webpathology.com)].