Don't be IHC

A 46 year old woman was diagnosed with ductal carcinoma in situ on a core biopsy specimen; the case presented is from the excisional biopsy specimen.

Image 1.  Excisional biopsy specimen shows an epithelial proliferation within dilated ducts (left) and the recent biopsy site.  Several separate small cellular nests (arrow) have an infiltrative appearance.

Image 2.   The duct contain a uniform population of cells arranged as cribriform structures, diagnostic of low grade ductal carcinoma in situ.  The DCIS involves a dilated duct, and there are a few fibrovascular cores (arrow) associated with the DCIS, characteristic of involvement of an intraductal papilloma. 

Image 3.  Small CRIBRIFORM structures appear infiltrative.

Diagnosis and discussion:

Image 4.  Immunohistochemical studies using antibodies to p63 show only rare myoepithelial cells ASSOCIATED WITH THE SMALL CRIBRIFORM STRUCTURES.

Low grade ductal carcinoma in situ, involving an intraductal papilloma, with biopsy site changes. 

Papillary lesions are frequently friable, and easily disrupted by biopsy procedures.  This small group of glands (image 3) is arranged in a linear fashion, and entrapped within granulation tissue, characteristic of epithelial displacement from the previous biopsy procedure.  The cribriform architecture is identical to that of the DCIS; often degenerating fibrovascular cores may be seen associated with entrapped epithelium. Myoepithelial cells are often disrupted as well, with little or no p63 expression.