Breast Biopsy Results - A High Risk Lesion

Many lesions in the breast that are palpated as a lump or that are identified on mammography are benign.  These benign lesions do not significantly raise the risk of developing breast cancer nor do they have a higher likelihood of ultimately turning into a breast cancer.

There is a smaller subset of benign lesions, though, that are considered at higher risk.  These lesions raise the risk of the patient ultimately developing breast cancer, and they can be associated with or adjacent to a cancer.  These high risk lesions comprise a group of abnormalities called atypia and include: atypical ductal hyperplasia, atypical lobular hyperplasia, columnar cell hyperplasia with atypia, flat epithelial atypia and papilloma with atypia.  These lesions occur within breast ducts and lobules or glands.  The lining of the ducts is thickened by too many cells (hyperplasia), and the cells are becoming abnormal (atypia).

When this process occurs within a duct it is called atypical ductal hyperplasia (ADH); when it occurs in the lobule it is called atypical lobular hyperplasia (ALH).  Both of these lesions are significant in that they increase the relative risk of a woman developing breast cancer by 4 to 5 times.  When the patient also has a family history the risk is even higher.  In addition, ADH and ALH may progress on to become breast cancer.  ADH and ALH are most often detected on mammography as a group of microcalcifications.  On breast MRI these lesions may be detected as a focal area of contrast enhancement.  These findings are typically evaluated by performing a tissue sampling known as core needle biopsy or vacuum-assisted biopsy. 

When ADH or ALH lesions are diagnosed on a core needle biopsy of the breast, surgical excision is recommended.    Excision is performed to remove any remainder of the focus of abnormal cells, but also to verify that there are no cancer cells adjacent to the lesion.  The difference pathologically between ADH and early carcinoma (low grade ductal carcinoma in situ) is sometimes only the number of ducts involved with the abnormal cells.  When a vacuum-assisted needle biopsy of the breast is performed and shows ADH, the chance of early cancer being found at surgical excision is approximately 10%. 

Other lesions that may be diagnosed on core biopsy and that carry some increased risk are papillomas and radial scars.  These lesions are benign but may be associated with atypia (ADH) or even carcinoma in situ (DCIS).  For this reason, many radiologists and clinicians recommend excision of a papilloma or radial scar diagnosed on core biopsy.

The papilloma is a small polyp-like mass that develops within a milk duct and is connected to the wall of the duct by a stalk.  The papilloma may twist on the stalk causing it to bleed, and the patient may experience bloody nipple discharge.  The papilloma may be detected on mammography as a small mass or group of calcifications that prompt a biopsy.

A radial scar is thought to develop from a papilloma that becomes sclerosed or scarred.  Surrounding dense fibrosis tissue and fat trapped within the radial scar create the appearance of a spokewheel or star.  The cells within the radial scar are often hyperplastic and may become atypical.  For this reason, when a sample in a core biopsy shows a radial scar, it is usually surgically excised to remove any potential high risk lesion.

Although many patients are worried when a high risk lesion is found, we must recognize that the detection of these can lead to the prevention of the formation of breast cancer.  Close follow-up with annual mammography is performed as well as screening MRI in many patients.  In addition some patients may be candidates for treatment with drugs such as Tamoxifen or Evista which can significantly reduce their risk of developing breast cancer.

Written By - Ellen Shaw de Paredes, MD, FACR