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Sclerosing adenosis of the breast

Dr Ayush Goel and Radswiki et al.

Sclerosing adenosis (SA) is a benign (non-cancerous) condition of the breast in which extra tissue develops within the breast lobules (the small portions of the glands that can produce milk). It is sometimes placed under the category of borderline breast disease.

In women with sclerosing adenosis, multiple small, firm, tender lumps (called nodules); fibrous tissue; and sometimes small cysts (i.e. sacs filled with fluid or semi-solid material) form in the breast. 

Clinical presentation

Many women with sclerosing adenosis experience recurring pain that tends to be linked to the menstrual cycle.

In most cases, sclerosing adenosis is detected during routine mammograms or following breast surgery. Usually, a biopsy (i.e. examination of a sample of tissue under the microscope) is required to confirm the diagnosis, because the condition is otherwise difficult to distinguish from breast cancer.

Sclerosing adenosis can appear as focal or diffuse and clinically it is not palpable in 80% of the cases, while in some cases, it might determine skin retraction.


Sclerosing adenosis is a type of adenosis, the  latter being a proliferative lesion of the terminal duct lobular unit characterized by an increased number of acini that may either produce a mass (florid adenosis, or the extreme, adenosis tumor) or become surrounded by stromal sclerosis (sclerosing adenosis). Adenosis represents a spectrum of benign alterations of breast tissue. Adenosis and sclerosing adenosis retain the lobular architecture, but it becomes exaggerated and distorted. The involved lobules show an increased number of acini, which become compressed and obliterated by stromal fibrosis.


Sclerosing adenosis can be seen as a component of other proliferative lesions, such as:

Radiographic features


On mammography, sclerosing adenosis may consist of architectural distortion, indeterminate microcalcifications (can be present in ~40-55% of cases 5-6) , or both. At times a mass lesion or asymmetrical density may be present. It can be therefore very difficult to mammographically distinguish from an infiltrating carcinoma.


It is considered an independant risk factor for development of subsequent breast cancer 3. Clinical research suggests that women with sclerosing adenosis may have approximately 1.5-2 times as high a risk of developing breast cancer.  

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