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Breast malignant, males, children

Carcinoma subtypes

Myoepithelial carcinoma


Reviewer: Monika Roychowdhury, M.D. (see Reviewers page)
Revised: 6 October 2012, last major update September 2012
Copyright: (c) 2001-2012, PathologyOutlines.com, Inc.

Definition
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● Rare tumor composed solely of cytologically malignant myoepithelial cells with mitotic activity

Terminology
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● Also called malignant myoepithelioma

Epidemiology
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● Median age 60 years

Prognostic features
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● 2 and 5 year survival is 88% and 55% (Eur J Surg Oncol 2004;30:357)

Case reports
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● 52 year old woman with infiltrating tumor (Diagn Pathol 2008;3:7)
● 69 year old woman with tumor arising in adenomyoepithelioma (Pathol Int 2006;56:211)
● 70 year old woman with myoepithelial carcinoma of the breast (Br J Radiol 2005;78:444)

Treatment
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● Complete excision with negative margins

Gross description
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● Up to 21 cm, well-defined with focal marginal irregularity and may be stellate
● Large tumors may have hemorrhage and necrosis

Micro description
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● Infiltrating spindle cells with fibrillar eosinophilic cytoplasm
● Tumor appears to arise from myoepithelial cells of ductules at periphery of lesion
● Cells have variable atypia
● Mitotic figures common, but may be less than 4/10 HPF
● May have clear cells (Tohoku J Exp Med 2003;200:103), due to glycogen (J Clin Pathol 1997;50:700)
● May have necrosis
● Infiltrative growth pattern most frequently with thin anastomosing cords of tumor cells associated with an intimately admixed reactive spindle cell stroma (Virchows Arch 2010;457:337)

Micro images
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Irregular dense proliferation        Tumor cells invade normal           Tumor infiltration of stroma
of pleomorphic spindle cells        breast tissue

                         
Myoepithelial carcinoma in          Foci of epithelioid cells
adenomyoepithelioma with
spindle cell elements

                         
S100+                                             p63+

       
Various images

Cytology description
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● Cohesive cell groups composed of spindle cells with atypical cigar-shaped nuclei
● Also epithelioid cells, mitotic figures

Cytology images
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Crowded haphazard cluster of          Nest of pleomorphic cells is composed
cells in metachromatic stroma          of large epithelioid, plasmacytoid and spindle cells

Positive stains
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Myoepithelial markers: smooth muscle actin, S100 and p63
● Also CD10, cytokeratin (pankeratin, CK5 and CK14), vimentin, EGFR
● Reactive stroma: weak positivity for calponin, S100 and smooth muscle actin (Virchows Arch 2010;457:337)

Negative stains
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● ER, PR, HER2

Electron microscopy description
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● Perinuclear tonofilaments, subplasmalemmal bundles of microfilaments with dense bodies, intermediate junctions, poorly developed desmosomes, pinocytic vesicles and fragmented external lamina (Int J Surg Pathol 2002;10:281)

Differential diagnosis
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Spindle cell carcinoma: negative for myoepithelial markers
Fibromatosis: no dominant nodule
Myofibroblastic lesions: usually no dominant nodule, keratin negative

Additional references
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J Clin Pathol 2003;56:497, Pathol Res Pract 2012;208:147

End of Breast malignant, males, children > Carcinoma subtypes > Myoepithelial carcinoma


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