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Table of Contents
Definition / general | Terminology | Epidemiology | Prognostic factors | Case reports | Treatment | Gross description | Microscopic (histologic) description | Microscopic (histologic) images | Cytology description | Cytology images | Positive stains | Negative stains | Electron microscopy description | Differential diagnosis | Additional referencesCite this page: Myoepithelial carcinoma. PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastmalignantmyoepithelialca.html. Accessed July 14th, 2017.
Definition / general
- Rare tumor composed solely of cytologically malignant myoepithelial cells with mitotic activity
Terminology
- Also called malignant myoepithelioma
Epidemiology
- Median age 60 years
Prognostic factors
- 2 and 5 year survival is 88% and 55% (Eur J Surg Oncol 2004;30:357)
Case reports
- 52 year old woman with infiltrating tumor (Diagn Pathol 2008;3:7)
- 60 year old woman with 3 x 3 cm lump in upper inner quadrant of left breast (Case of the Week #407)
- 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
- Complete excision with negative margins
Gross description
- Up to 21 cm, well defined with focal marginal irregularity and may be stellate
- Large tumors may have hemorrhage and necrosis
Microscopic (histologic) description
- 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)
Microscopic (histologic) images
Images hosted on PathOut server:
Case of the Week #407:
p63+
CK 5/6+
pan CK
Ki67 (high index)
ER-
PR+ (weak)
HER2-
Images hosted on other servers:
Irregular dense proliferation of pleomorphic spindle cells
Tumor cells invade normal breast tissue
Figs 3E & 3F: adenomyoepithelioma with spindle cell elements & epithelioid cell elements
p63+
Various images
Cytology description
- Cohesive cell groups composed of spindle cells with atypical cigar shaped nuclei
- Also epithelioid cells, mitotic figures
Cytology images
Images hosted on other servers:
cluster of cells
in metachro-
matic stroma
Nest of pleomorphic cells
is composed of large
epithelioid, plasmacytoid
and spindle cells
Positive stains
- 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)
Electron microscopy description
- 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
- Fibromatosis: no dominant nodule
- Myofibroblastic lesions: usually no dominant nodule, keratin negative
- Spindle cell carcinoma: negative for myoepithelial markers
Additional references
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