Adenosis in Mammography

Adenosis is hyperplasia of epithelial and myoepithelial cells of the ductules of the terminal ductal lobular unit (TDLU) and the surrounding intralobular stroma. This results in enlargement of the TDLU. Adenosis may be blunt duct type, microglandular, or sclerosing.

Sclerosing adenosis refers to stromal sclerosis involving greater than half of the TDLU that results in enlargement, distortion, and compression of the TDLU. About 50% of cases are associated with calcifications.

Sclerosing adenosis is important because it sometimes presents a diagnostic dilemma for the pathologist by mimicking infiltrating carcinoma, tubular carcinoma in particular. Sclerosing adenosis may also mimic a radial scar by pathology.

On the radiologist's end, sclerosing adenosis more commonly presents with calcifications, but can also present as a spiculated lesion. By itself, sclerosing adenosis is thought to cause a mild (1.7-2.5x) increase in the risk of infiltrating breast cancer. When associated with atypical hyperplasia, the relative risk rises to as much as 6.7.

References

Cyrlak D, Carpenter PM, Rawal NB. Breast imaging case of the day. Florid sclerosing adenosis. Radiographics. 1999 Jan-Feb;19(1):245-7.