Breast Pathology

2020 Edition
| Editors: Anna Sapino, Janina Kulka

Microinvasive Carcinoma of the Breast

  • Simonetta BianchiEmail author
  • Vania Vezzosi
Reference work entry


Microinvasive carcinoma, pT1mi, Invasive carcinoma less than or equal to 1 mm in greatest dimension


Microinvasive carcinoma (MIC) of the breast was not clearly characterized until 1997 when the Union for International Cancer Control (UICC) first included pT1mic in the TNM classification of breast carcinoma. It was defined as “invasive mammary carcinoma with no focus exceeding 1 mm in greatest dimension.”

This definition has been carried through many editions of the Cancer Staging Manual published by American Joint Committee on Cancer (AJCC) until the current edition (Amin et al. 2017) where it is reported as “an invasive carcinoma with no focus measured larger than 1 mm and classified as pT1mi. MIC is reported as nearly always encountered in a setting of ductal carcinoma in situ (DCIS) (  Ductal Carcinoma In Situ) (Fig. 1, (a) H&E. (b) Immunostaining for smooth-muscle myosin heavy chain highlights myoepithelial cells around the DCIS, while it is absent in the...
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References and Further Reading

  1. Amin, M. B., Edge, S. B., Greene, F. L., et al. (Eds.). (2017). AJCC cancer staging manual (8th ed.pp. 589–628). New York: Springer.Google Scholar
  2. Bianchi, S., & Vezzosi V. (2008). Microinvasive Carcinoma of the Breast. Pathology and Oncology Research, 14, 105–111.PubMedCrossRefGoogle Scholar
  3. Cserni, G., Wells, C. A., Kaia, H., et al. (2016). Consistency in recognizing microinvasion in breast carcinomas is improved by immunohistochemistry for myoepithelial markers. Virchows Archive, 468, 473–481.CrossRefGoogle Scholar
  4. Hilson, J. B., Schnitt, S. J., & Collins, L. C. (2009). Phenotypic alterations in ductal carcinoma in situ-associated myoepithelial cells: Biologic and diagnostic implications. The American Journal Surgical Pathology, 33, 227–232.CrossRefGoogle Scholar
  5. Hoda, S. A. (2014). Ductal carcinoma in situ. In S. A. Hoda, E. Brogi, F. C. Koerner, & P. P. Rosen (Eds.), Rosen’s breast pathology (4th ed., pp. 331–411). Philadelphia: Lippincott Williams & Wilkins.Google Scholar
  6. Morita, M., Yamaguchi, R., Tanaka, M., et al. (2016). Two progressive pathways of microinvasive carcinoma: Low-grade luminal pathway and high grade HER2 pathway based on high tumor-infiltrating lymphocytes. Journal of Clinical Pathology, 69, 890–898.PubMedCrossRefGoogle Scholar
  7. Pinder, S. E., Ellis, I. O., Schnitt, S. J., et al. (2012). Microinvasive carcinoma. In S. R. Lakhani, I. O. Ellis, S. J. Schnitt, et al. (Eds.), WHO classification of tumours of the breast (pp. 96–97). Lyon: International Agency for Research on Cancer.Google Scholar
  8. Schnitt, S. J., & Collins, L. C. (Eds.). (2013). Biopsy interpretation of the breast (2nd ed.pp. 267–281). Philadelphia: Lippincott Williams & Wilkins.Google Scholar

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© Springer Nature Switzerland AG 2020

Authors and Affiliations

  1. 1.Division of Pathological Anatomy, Department of Surgery and Translational MedicineUniversity of Florence, School of Human Health SciencesFlorenceItaly