Breast malignant, males, children
Carcinoma subtypes
Myoepithelial carcinoma

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

Revised: 8 November 2016, last major update September 2012

Copyright: (c) 2001-2016, PathologyOutlines.com, Inc.

PubMed search: myoepithelial carcinoma[title] breast
Cite this page: Myoepithelial carcinoma. PathologyOutlines.com website. http://pathologyoutlines.com/topic/breastmalignantmyoepithelialca.html. Accessed December 3rd, 2016.
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
Case Reports
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
Micro 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)
Micro 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:

Crowded haphazard cluster of cells in metachromatic 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)
Negative Stains
  • ER, PR, HER2
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