Rosen's Breast Pathology, 4e

FIG. 11.67.  DCIS and microinvasive carcinoma. A: Car- cinoma protrudes from a duct with solid DCIS. Note the stromal reaction including minute blood vessels directed toward the protruding carcinoma . In this plane of sec- tion, the finding is ambiguous and not diagnostic of inva- sion because this could be a tangential section of a small secondary duct exiting the large duct. Immunostains for basement membrane components, myoepithelial cells, and cytokeratin are helpful in analyzing such foci. B,C: This focus from the same case as (A) provides stronger evidence for microinvasion because there appears to be greater disruption of the protruding epithelium includ- ing isolated cell clusters (B) in the stroma. Note the small blood vessel directed at the site of invasion (C) .

FIG. 11.68.  DCIS and microinvasive carcinoma. A: Two isolated carcinoma cells ( arrow ) in the periductal stroma adjacent to a tangentially sectioned duct containing DCIS. B: Disruption of the basement membrane is evident, and there are carcinoma cells in the periductal stroma ( arrows ). C: A larger focus of microinvasion ( upper right ) with a marked lymphocytic reaction.

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