Breast nonmalignant
Myoepithelial neoplasms
Myoepithelioma


Topic Completed: 1 April 2010

Revised: 9 September 2019

Copyright: 2002-2019, PathologyOutlines.com, Inc.

PubMed Search: Myoepithelioma [title] breast [title]

Hind Warzecha, M.D.
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Cite this page: Nassar H. Myoepithelioma . PathologyOutlines.com website. http://www.pathologyoutlines.com/topic/breastmyoepithelioma.html. Accessed December 11th, 2019.
Definition / general
  • Bland spindle cell lesion with myoepithelial phenotype
Terminology
Epidemiology
  • Rare
Clinical features
  • Usually benign, may recur locally
Case reports
Microscopic (histologic) description
  • Dense spindle cell neoplasm, may be arranged in storiform pattern
  • Tumor cells have eosinophilic cytoplasm, oval and regular nuclei
  • May have polygonal cells with clear cytoplasm and hyperchromatic nuclei
  • May infiltrate fat or surround normal ducts
  • No mitotic figures, no necrosis, no atypia
Microscopic (histologic) images

AFIP images

Invasive dense spindle cell lesion

Plump interlacing spindle cells with ovoid nuclei

 

Occasional
polygonal cells with
hyperchromatic
nuclei

Actin+ spindle
cells with positive
internal control in
normal duct at top



Images hosted on other servers:

Broad fascicles

Resembles leiomyoma

Muscle specific actin+

Cytology description
  • Epithelial and spindled cells
  • Mild to moderate nuclear pleomorphism, occasional intranuclear cytoplasmic vacuoles, naked bipolar cells, metachromatic myxoid or fibrillary material
  • No necrosis, no mitotic figures
Positive stains
Negative stains
Electron microscopy description
  • Activated, differentiated myoepithelial cells (cytoplasmic bundles of myofilaments, desmosomes and basal lamina), variable squamous metaplasia (Am J Surg Pathol 1982;6:785)
Differential diagnosis
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