Blunt duct adenosis of the breast

Last revised by Ranjit Singh on 24 Nov 2023

Blunt duct adenosis of the breast or more simply blunt adenosis is a benign proliferative process that affects mainly the lobular (acinar) component of the breast parenchyma 1,2. It is a confusing entity with some describing it as a subset of adenosis 1 and others a subset of columnar cell lesions 2.

Blunt duct adenosis is a term used to describe distended terminal ducts that have a columnar epithelium lining the central extracellular lumen with a normal lining of myoepithelial cells adjacent to the basement membrane. These distended ducts are often found to have clustered calcium phosphate microcalcifications 1.

The WHO 2012 considered BDA and columnar cell changes to be synonymous, while columnar cell lesions, especially those with atypia, are part of a spectrum of early precursors of the low nuclear grade breast neoplasia family. In the updated WHO 2019 version, BDA is listed as ‘not recommended’ terminology for columnar cell lesions without further discussing it, leaving the question open if BDA should be considered a separate entity.

There is very little published literature regarding imaging findings of blunt duct adenosis (c.2023).

At mammography, blunt duct adenosis can present as small, oval or round clustered punctate microcalcifications or circumscribed masses.

At ultrasound, blunt duct adenosis has been reported to present as mostly circumscribed masses, however non-circumscribed margins have also been reported. One study did find blunt duct adenosis presenting as focal acoustic shadowing without mass configuration.

Blunt duct adenosis, and adenosis in general, is not considered a premalignant lesion. However, radiological findings of adenosis can be quite similar to other benign or malignant lesions of the breast and thus either tissue / excisional biopsy, depending on the institution, or short interval serial imaging surveillance is warranted.