Your pathology report for columnar cell change of the breast

by Jason Wasserman MD PhD FRCPC
August 10, 2025

Columnar cell change is a non-cancerous alteration that can occur in the small structures of the breast known as terminal duct lobular units (TDLUs). In this change, the tiny glands (acini) inside the TDLU become slightly enlarged and are lined by cells that are taller than usual, called columnar epithelial cells. In some cases, there are more than one or two layers of these cells, a finding called columnar cell hyperplasia.

A related change, called flat epithelial atypia (FEA), happens when the columnar cells also show mild changes in their appearance under the microscope (cytologic atypia). Both columnar cell change and FEA are considered part of a group called columnar cell lesions.

Where in the breast are these lesions found?

Columnar cell change and FEA develop in the terminal duct lobular units, which are the small lobules and ducts that produce and carry milk during breastfeeding. They are microscopic changes and cannot be seen or felt during a physical exam.

What causes columnar cell change?

The exact cause of columnar cell change is not known. However, research has shown that these changes share similar biological features with other low-grade breast changes, such as atypical ductal hyperplasia (ADH), low-grade ductal carcinoma in situ (DCIS), and some types of low-grade invasive breast cancer.

This suggests that columnar cell lesions may represent an early step in a “low-grade breast neoplasia pathway,” a sequence of changes that can, in some cases, progress to more advanced breast disease. Many columnar cell lesions show genetic changes, such as loss of a part of chromosome 16 (called 16q loss), which is also found in low-grade breast cancers.

How is columnar cell change found?

Columnar cell change usually does not cause any symptoms and cannot be felt during a breast exam. Most cases are found during a mammogram performed for screening. They are often detected because they are associated with tiny deposits of calcium (microcalcifications) that appear as small white spots on the mammogram. Sometimes, they are found incidentally when a biopsy is performed for another reason.

How is this diagnosis made?

The diagnosis is made by examining a small sample of breast tissue under a microscope. The sample is usually obtained through a core needle biopsy, which may be performed after microcalcifications are seen on a mammogram. The pathologist will look for the specific microscopic features that define columnar cell change, columnar cell hyperplasia, or flat epithelial atypia.

What does columnar cell change look like under the microscope?

Under the microscope, the affected lobules show slightly enlarged glands lined by one or more layers of column-shaped cells. These cells often have small, evenly spaced nuclei and may have a small bump, called an apical snout, pointing into the center of the gland. The glands often contain secretions or calcifications.

In columnar cell hyperplasia, the lining is more than two cell layers thick. In flat epithelial atypia, the cells look more uniform and round, and the nuclei resemble those seen in low-grade DCIS, but the glands remain flat without the complex patterns seen in DCIS.

Is columnar cell change a type of cancer?

No. Columnar cell change and columnar cell hyperplasia are not cancer. Flat epithelial atypia is also not cancer but is considered a non-obligate precursor, meaning it may be an early step toward the development of certain low-grade breast cancers in some women. Most columnar cell lesions never progress to cancer.

Does columnar cell change increase my risk of breast cancer?

Studies suggest that columnar cell change and hyperplasia are linked to a slightly increased risk of developing breast cancer in the future. The risk is higher if other abnormal breast changes, such as atypical ductal hyperplasia or lobular neoplasia, are also present.

Flat epithelial atypia may, in rare cases, progress to invasive cancer, but the risk is much lower than for other precancerous lesions like ADH.

What happens after a diagnosis of columnar cell change?

In most cases, no further treatment is needed for columnar cell change or hyperplasia alone, especially if the changes are completely removed during the biopsy. If flat epithelial atypia is diagnosed, your doctor may recommend further assessment to make sure there are no more serious changes in the breast tissue.

If all the microcalcifications are removed during the biopsy and imaging results match the pathology findings, surgery is often not required. Decisions are based on the individual situation, and your care team will consider your overall risk factors for breast cancer.

Prognosis

Columnar cell change and hyperplasia have an excellent prognosis. Most women do not develop any further problems from these changes. The risk of progression to cancer is very low, especially in the absence of other high-risk lesions. Regular breast screening is usually recommended as part of routine health care.

Questions to ask your doctor

  • Was my biopsy result completely explained by the imaging findings?

  • Were all the microcalcifications removed during my biopsy?

  • Do I need surgery or is close follow-up enough in my case?

  • How often should I have follow-up imaging?

  • Does this finding increase my personal risk for breast cancer?

  • Should I consider a risk assessment or genetic counseling based on my results?

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