11th April 2024

Non-proliferative lesions

The commonest non-proliferative breast lesions are breast cysts. A breast cyst is a fluid-filled circular or ovoid mass derived from the terminal duct lobular unit. They are classified as simple, complex or complicated based on their sonographic features. The management of a breast cyst is guided by an imaging classification score (see investigation subheading below). In summary, for a simple cyst, no further intervention is necessary. Fine needle aspiration (FNA) is only performed when there are signs of infection. The management of a complicated cyst depends on the imaging classification score. A complex cyst requires core needle biopsy (CNB) for diagnosis.

Galactoceles, also known as milk retention cysts, are collections caused by an obstructed milk duct. These occur almost exclusively in lactating women. Ultrasound may show features of a complex mass. Aspiration yields a milky substance. There is no increased risk of subsequent breast cancer, and excision is not necessary. 

Other non-proliferative changes include papillary apocrine change and mild hyperplasia of the usual type.