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    • Surgical Pathology Criteria
    http://surgpathcriteria.stanford.edu/

    Myoepithelioma of the Breast

    Definition

    • Bland spindle cell lesion of the breast with a myoepithelial cell phenotype

    Diagnostic Criteria

    • Monomorphic cytologically bland spindle cells
      • Elongate nuclei
      • No pleomorphism
      • No mitotic figures
      • Clear to eosinophilic cytoplasm
    • Interlacing groups of cells, may be stellate or solid masses
      • May infiltrate fat
      • May surround normal ducts
    • Myoepithelial phenotype

    Richard L Kempson MD
    Robert V Rouse MD
    Department of Pathology
    Stanford University School of Medicine
    Stanford CA 94305-5342

    Original posting:: May 27, 2006

    Supplemental studies

    Immunohistology

    • Actin, myosin, keratin positive
    • Not reported, but expected to be positive for calponin and p63

    Differential Diagnosis

     

    Adenomyoepithelioma Myoepithelioma
    Biphasic with myoepithelial and tubular components Purely myoepithelial, may surround normal ducts
    Circumscribed May be stellate

     

    Myoepithelial Carcinoma Myoepithelioma
    Cytologically malignant Cytologically bland
    Frequent mitotic figures Mitotically inactive
    Necrosis may be present No necrosis

     

    Myofibroblastoma Myoepithelioma
    Circumscribed May be stellate
    Keratini negative Keratin positive
    CD34 positive CD34 not reported but expected to be negative

     

    Metaplastic Carcinoma Myoepithelioma
    Contains malignant epithelial component No epithelial component
    Mesenchymal component, if present is usually cytologically malignant Bland spindle cell population

    Clinical

    • Very rare
    • No aggressive behavior or metastases reported

    Lists

    Breast Tumors and Lesions Exhibiting Reactivity for Muscle/Myoepithelial Markers

    (Most benign lesions with an epithelial component will have a myoepithelial cell layer)

    Bibliography

    • Bigotti G, Di Giorgio CG. Myoepithelioma of the breast: histologic, immunologic, and electromicroscopic appearance. J Surg Oncol. 1986 May;32(1):58-64.
    • Erlandson RA, Rosen PP. Infiltrating myoepithelioma of the breast. Am J Surg Pathol. 1982 Dec;6(8):785-93.
    • Hamperl H. The myothelia (myoepithelial cells). Normal state; regressive changes; hyperplasia; tumors. Curr Top Pathol. 1970;53:161-220.
    • Rode L, Nesland JM, Johannessen JV. A spindle cell breast lesion in a 54-year-old woman. Ultrastruct Pathol. 1986;10(5):421-5.
    • Toth J. Benign human mammary myoepithelioma. Virchows Arch A Pathol Anat Histol. 1977 Jun 23;374(3):263-9.
    Printed from Surgical Pathology Criteria: http://surgpathcriteria.stanford.edu/
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