Your pathology report for columnar cell hyperplasia of the breast

By Jason Wasserman MD PhD FRCPC
August 10, 2025

Columnar cell hyperplasia is a non-cancerous change that can occur in the small structures of the breast called terminal duct lobular units (TDLUs). In this condition, the glands (acini) inside the TDLU become slightly enlarged and are lined by more than two layers of tall, column-shaped cells. This increased layering of cells is what hyperplasia means — a higher than normal number of cells.

Columnar cell hyperplasia is part of a group of changes called columnar cell lesions, which also includes columnar cell change and flat epithelial atypia (FEA). These changes are related to each other and may represent different points along the same biological pathway.

Where in the breast is columnar cell hyperplasia found?

Columnar cell hyperplasia occurs in the terminal duct lobular units, the small lobules and ducts that produce and carry milk during breastfeeding. These changes are microscopic and cannot be seen or felt during a physical exam.

What causes columnar cell hyperplasia?

The exact cause is not known. However, research has shown that columnar cell hyperplasia shares many biological and molecular features with other low-grade breast lesions such as atypical ductal hyperplasia (ADH), low-grade ductal carcinoma in situ (DCIS), and some low-grade invasive breast cancers.

These similarities include specific genetic changes, such as the loss of part of chromosome 16 (16q loss). Because of these shared features, columnar cell hyperplasia is thought to be an early step in the “low-grade breast neoplasia pathway” — a sequence of changes that, in some cases, can progress to more advanced breast disease.

How is columnar cell hyperplasia found?

This condition usually does not cause symptoms and is not detectable by touch. Most cases are found during a screening mammogram. Columnar cell hyperplasia is often associated with tiny calcium deposits in the breast (microcalcifications) that appear as small white spots on a mammogram. Less often, it is found by chance when a biopsy is performed for another reason.

How is this diagnosis made?

Columnar cell hyperplasia is diagnosed by looking at a breast tissue sample under a microscope. The tissue is most often collected with a core needle biopsy, usually after a mammogram shows microcalcifications. The pathologist makes the diagnosis based on the characteristic appearance of the cells and the number of layers lining the glands.

What does columnar cell hyperplasia look like under the microscope?

When examined under the microscope, the affected lobules contain enlarged glands with irregular shapes, lined by tall columnar cells arranged in more than two layers. These cells often have small, evenly spaced nuclei and may have small protrusions called apical snouts pointing into the center of the gland. The glands frequently contain secretions or calcifications.

In contrast to flat epithelial atypia, the nuclei in columnar cell hyperplasia look normal (no cytologic atypia). The increased layering of cells, rather than changes in nuclear appearance, is the main feature that separates hyperplasia from simple columnar cell change.

Is columnar cell hyperplasia a type of cancer?

No. Columnar cell hyperplasia is not cancer. It is considered a benign (non-cancerous) breast change. However, it may be part of a sequence of changes that, in rare cases, can lead to certain low-grade breast cancers. Most women with columnar cell hyperplasia never develop breast cancer as a result of this finding.

Does columnar cell hyperplasia increase my risk of breast cancer?

Some studies suggest that columnar cell hyperplasia may be linked to a slightly increased risk of developing breast cancer in the future, especially if other higher-risk lesions are also present. On its own, the risk is considered low, but it is higher than for women without any proliferative breast changes. Your overall risk also depends on other personal and family health factors.

What happens after a diagnosis of columnar cell hyperplasia?

In most cases, no additional treatment is needed if the biopsy removes all of the area that was seen on imaging. Because columnar cell hyperplasia is not cancer and does not have atypia, surgery is usually not required. Your healthcare team will decide on the next steps based on your imaging findings, your pathology report, and your overall risk factors.

Prognosis

The outlook for women with columnar cell hyperplasia is excellent. Most women do not develop further problems from this finding. Regular breast screening according to your doctor’s recommendations is usually all that is required.

Questions to ask your doctor

  • Was my diagnosis columnar cell hyperplasia without atypia?

  • Were the changes in my biopsy completely removed during the procedure?

  • Do I need any additional surgery or follow-up imaging?

  • How often should I have mammograms after this finding?

  • Does this result change my overall risk for breast cancer?

  • Should I have a formal breast cancer risk assessment or genetic counseling?

A+ A A-