Breast malignant, males, children
Breast cancer
Microinvasive carcinoma

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

Revised: 20 October 2016, last major update February 2012

Copyright: (c) 2002-2016,, Inc.

PubMed Search: Microinvasive carcinoma

Cite this page: Microinvasive carcinoma. website. Accessed October 25th, 2016.
Definition / General
  • Dominant lesion is not invasive, but there are 1+ separate small, microscopic foci of infiltration, each 1 mm or less in size
  • “Minimal breast carcinoma” includes microinvasive carcinoma and DCIS
  • Can confirm using myoepithelial stains (myoepithelial layer is not intact) and keratin (to observe infiltrative growth)
  • Diagnosis requires certainty of invasion; if doubt remains after recuts and immunostains, call DCIS or suspicious
  • Mean age 61 years
Clinical Features
  • Less than 1% of all breast cancers
  • Usually detected by mammography due to abnormal calcifications in associated DCIS
  • 72% associated with comedo DCIS, 89% with high nuclear grade and 89% with necrosis
  • Sentinel lymph node dissection may be appropriate, although axillary nodal metastases occur in less than 10% (Breast J 2008;14:335, Breast 2008;17:395); controversial whether to perform complete axillary dissection if positive sentinel node (yes - Breast 2007;16:146, no - Am J Surg 2007;194:845)
  • Commonly misdiagnosed, as true diagnosis is usually DCIS or T1a carcinoma (Cancer 2000;88:1403)
  • In breast core needle biopsies, invasive carcinomas 1 mm or less are rare, are associated with DCIS and ADH, and often with large invasive foci at excision (Arch Pathol Lab Med 2004;128:996)
  • Report number of foci of invasion, size of largest focus
Micro Description
  • Usually ductal, rarely tubular or lobular morphology
  • Nodules of invading neoplastic cells in periductal or perilobular stroma, none exceeding 1.0 mm
  • Usually arises in background of high grade DCIS; stromal microinvasion typically associated with fibroblast proliferation, collagenization and focal inflammation
  • False positives: lobular cancerization, radial scar, sclerosing adenosis (Arch Pathol Lab Med 2001;125:1259)
  • False negatives: masking of invasion by inflammatory cells or histiocytes; use cytokeratin to highlight tumor cells
Micro Images

Images hosted on other servers:

With high grade DCIS

Examples from core biopsies

Tumor breaches basement membrane

Invasive carcinoma (arrow) < 1 mm, surrounded by DCIS

High grade DCIS with foci of microinvasion

Figures 1, 2 and 3

Figure 1

Fig A: false negative due to inflammatory cells
Fig B: false negative due to mistaking tumor cells for histiocytes
Fig C: AE1-3 distinguishes tumor cells (+) from inflammatory cells (-)
Fig D: smooth muscle actin highlights myoepithelial cells in benign but not malignant lesions

Negative Stains
Additional References