Adenomyoepithelioma

Breast - nonmalignant
Benign (usually) tumors / tumor like-changes
Adenomyoepithelioma

Author: Monika Roychowdhury, M.D., FCAP (see Authors page)

Revised: 10 March 2017, last major update June 2016

Copyright: (c) 2002-2017, PathologyOutlines.com, Inc.

PubMed Search: Adenomyoepithelioma [title] breast

Table of Contents

Cite this page: Adenomyoepithelioma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastadenomyo.html. Accessed July 14th, 2017.

Definition / general

Biphasic tumor composed of variable number of myoepithelial cells around small epithelial lined spaces
First recognized in the breast by Hamperl (Curr Top Pathol 1970;53:161)

Essential features

Biphasic tumor with epithelial and myoepithelial components
Benign to low grade malignant behavior and a propensity for recurrence
Either epithelial or myoepithelial component can show malignant transformation so thorough evaluation recommended
Wide surgical excision with appropriate margins recommended to prevent recurrence
Microscopy shows tubular or lobular structures with epithelial and myoepithelial components
IHC: Epithelial component is cytokeratin+, EMA+, CEA+; myoepithelial component is S100+, SMA+, SMM-HC+, p63+

Terminology

Other breast myoepithelial lesions are myoepitheliosis and myoepithelioma
WHO (2012) divides adnomyoepithelioma into a benign type (both components benign) and a form where malignant transformation is seen
Page recommends that cases with malignant histology not be called adenomyoepithelioma but be defined by the histology of the malignant component (Am J Surg Pathol 2005;29:1294)

Epidemiology

Uncommon, mean age 60 years
Rare in male breast

Sites

Usually occurs in the peripheral portion of the breast, but can be central
No predilection for either breast

Etiology

Considered a variant of intraductal papilloma

Clinical features

Usually presents as a mass
Usually benign, although may recur locally
Benign appearing tumors rarely metastasize to lung (Arch Pathol Lab Med 2006;130:1349)
Malignant tumors are usually low grade; may metastasize to lung, brain, jaws, lymph nodes
If metastasize, shows hematogenous spread, usually occurs in tumors > 1.6 cm in size (World J Surg Oncol 2013;11:285)

Prognostic factors

Mitotic rate > 3 MF / 10 HPF is associated with recurrence
Tubular variant and some lobular variants with high mitotic activity are prone to recurrence
High mitotic rate, atypia, necrosis, cellular pleomorphism and infiltrative borders favor malignancy

Case reports

48 year old woman with collagenous spherulosis in an adenomyoepithelioma of the breast (J Clin Pathol 2004;57:83)
56 year old woman with intracystic adenomyoepithelioma of the breast (Breast Cancer 2007;14:429)
Cellular adenomyoepithelioma of the breast (Am J Surg Pathol 1983;7:863)
Three patients with breast adenomyoepithelioma (AJR Am J Roentgenol 2003;180:799)
Diagnostic review of adenomyoepithelioma of the breast (Arch Pathol Lab Med 2013;137:725)

Malignant tumors

50 year old woman with malignant metastatic adenomyoepithelioma of breast (Hematol Oncol Stem Cell Ther 2009;2:364)
50 year old woman with malignant adenomyoepithelioma of the breast (Am J Surg Pathol 1998;22:631)
60 year old woman with breast adenomyoepithelioma (malignant transformation of epithelial and myoepithelial component, World J Surg Oncol 2013;11:285)
68 year old woman with breast mass, present for 14 years, gradually increasing in size (Case of the Week #418)
69 year old woman with myoepithelial carcinoma arising in an adenomyoepithelioma of the breast (Pathol Int 2006;56:211)
71 year old woman with malignant adenomyoepithelioma of the breast with malignant proliferation of epithelial and myoepithelial elements (Arch Pathol Lab Med 2000;124:632)
75 year old woman with rapidly increasing breast mass (Arch Pathol Lab Med 2004;128:235)
77 year old woman with malignant adenomyoepithelioma of the breast (Pathol Res Pract 2007;203:599)
80 year old woman with malignant adenomyoepithelioma of the breast (Eur J Gynaecol Oncol 2009;30:234)
Woman with radioresistant malignant myoepithelioma of the breast (J Med Imaging Radiat Oncol 2009;53:234)

Treatment

Wide local excision with appropriate margins
May recur with incomplete excision

Clinical images

Images hosted on PathOut server:

Mammogram - courtesy of Dr. Mark R. Wick

Images hosted on other servers:

Radiological characteristics of lesion

69 year old woman (fig 1A, 1B)

Gross description

Well circumscribed, usually small (mean 1 - 2 cm), but can be up to 8 cm
Firm
May have satellite nodules

Gross images

Images hosted on PathOut server:

Malignant adenomyoepithelioma - COW #418

Unusually large bisected tumor with central
cavity with bosselated contour (AFIP)

Images hosted on other servers:

Intracystic nodule

Microscopic (histologic) description

Well circumscribed, may be encapsulated or multinodular
Proliferation of epithelial and myoepithelial cells
Aggregated lobules of glands with tall lining epithelium with scant eosinophilic cytoplasm and hyperchromatic nuclei surrounded by myoepithelial cells with clear cytoplasm
Epithelial cells usually form glandular spaces
Myoepithelial cells can be dominant and may be spindle shaped, clear or polygonal
Apocrine metaplasia may be present, also adenomyoepitheliomatous hyperplasia
Variants include spindle cell type (epithelial lined spaces may be sparse, resembles leiomyoma), tubular variant (ill defined margins, may resemble tubular adenoma), lobulated variant (nests of myoepithelial cells surround compressed epithelial lined spaces)
Malignant appearing cases have local invasion, high mitotic rate, severe atypia (Am J Surg Pathol 1992;16:868)

Microscopic (histologic) images

Scroll to see all images.

Images hosted on PathOut server:

Malignant adenomyoepithelioma - COW #418

CK7 - COW #418

34βE12 - COW #418

CD117 - COW #418

p63 - COW #418

Smooth muscle myosin heavy chain - COW #418

Courtesy of Dr. Mark R. Wick

AFIP Images:

Intraductal bands of pale myoepithelium separate adenomatous ductal epithelium

Myoepithelial cells with clear cytoplasm crowd glandular epithelium and expand into stroma

Overgrowth of myoepithelium in two nodules separated by stromal band

Myoepithelial cells in small clusters have replaced most ductal elements

Foci of glands with luminal secretions

Isolated myoepithelial cells with clear vacuolated cytoplasm

Transition between adenomatous and myomatous growth

AE1+ glandular cells, (myoepothelial cells are negative)

Images hosted on other servers:

Proliferation of epithelial and myoepithelial cells

Multilobulated outlines and pushing margins

CK7 (A); p63 (B); CK5 (C); S-100 (D)

69 year old woman (fig 1C)

72 year old woman (fig 2C)

74 year old woman (fig 3C, 3D, 3E)

Solid sheets and cords of round, oval cells

Various images and stains

With collagenous spherulosis

Benign histology but malignant behavior:

Benign appearing tumors that metastasized to lung

Lung metastases with benign histology

Malignant histology:

Mitotic activity

Various images

Keratin+ epithelium

AE1-AE3, S100

Cytology description

Moderate to highly cellular with large clusters of epithelium and myoepithelium
Tubular structures occasionally found
Myoepithelium appears as small clusters or dispersed cells with epithelioid morphology, intranuclear or intracytoplasmic vacuoles, often naked bipolar nuclei
Mild to moderate nuclear atypia present
Metachromatic fibrillary stroma occasionally found
No mitotic figures, no necrosis
Often classified incorrectly as fibroadenoma, suspicious for malignancy or malignant (Cancer 2006;108:250)

Cytology images

Images hosted on other servers:

Various images

Positive stains

Epithelial component:
- Keratin (AE1-AE3), CK7, CK8 / 18, CEA, EMA; variable ER
Myoepithelial component:
- p63 (AJSP 2001;25:1054), S100, smooth muscle myosin heavy chain, CK5 / 14, SMA, EMA

Negative stains

Electron microscopy description

Myoepithelial features (classic) include myofibrils with dense bodies, pinocytotic vesicles, desmosomes or tight junctions, patchy basement membrane

Molecular / cytogenetics description

Case report with t(8;16)(p23;q21) (Cancer Genet Cytogenet 2005;156:14)

Differential diagnosis

Adenosis tumor: no prominent myoepithelial component
Intraductal papilloma: no prominent myoepithelial component
Invasive carcinoma (on core biopsy): unequivocal evidence of invasion
Nipple adenoma: no prominent myoepithelial component
Tubular adenoma: very well circumscribed (tubular variant is not), myoepithelial cells are inconspicuous or rare

Additional references

Hum Pathol 1987;18:1232, Stanford University