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Pathology FAQ: Atypical Hyperplasia


When your breast was biopsied, the samples taken were studied under the microscope by a specialized doctor with many years of training called a pathologist. The pathology report tells your treating doctor the diagnosis in each of the samples to help manage your care. This FAQ sheet is designed to help you understand the medical language used in the pathology report.

1. What does “hyperplasia” mean?

Normal milk glands are made up of small milk-making structures called acini that drain into ducts that carry milk to the nipple . These acini and ducts are lined by one layer of square cells on the inside and a layer of flat, muscular cells around the outside. Hyperplasia means the ducts or acini have become larger than usual and that the lining cells have made too many copies of themselves. This is an abnormal growth pattern that is associated with a small increase in breast cancer risk. In some women these cells can change and begin to look abnormal under the microscope. This is known as “atypical hyperplasia” which is a marker of significantly increased breast cancer risk.

2. What does it mean if my report says that the hyperplasia is “ductal” or “lobular?

Hyperplasia that arises in the milk-producing structures of the breast (acini) is called “lobular.” Hyperplasia that arises in the milk-transporting part of the breast (ducts) is called “ductal.”

3. What does it mean if my report mentions E-cadherin?

E-cadherin is a protein that helps cells stick to one another to build complex structures like milk glands. Lobular Hyperplasia, which arises in the acini, lacks E-cadherin. Ductal hyperplasia nearly always make plenty of E-cadherin. The pathologist will sometimes perform an E-cadherin test to help determine if a case of hyperplasia is ductal or lobular. If your report does not mention E-cadherin, it means that this test was not necessary to make the distinction.

4. What is the significance of “atypical ductal hyperplasia (ADH)”?

ADH is an abnormal appearing growth of cells within the breast ducts that is associated with an increased risk of subsequent breast cancer. If ADH is found on needle biopsy, a surgical excision (lumpectomy) is usually performed to make sure there is no cancer nearby. If only ADH is found on a surgical excision (lumpectomy), your doctor will calculate your breast cancer risk and discuss options for managing your risk. This may take the form of more frequent screening, screening with MRI or taking a medication to reduce your risk. Atypical Ductal Hyperplasia is very sensitive to estrogen your body makes. Medications to reduce breast cancer risk either interact directly with the estrogen receptors on the breast cells (tamoxifen and raloxifene) or lower the level of estrogen in your body (anastrazole. Letrazole, and exemestane).

5. What is the significance of “atypical lobular hyperplasia (ALH)”?

Atypical lobular hyperplasia arises in the acini of the milk glands. There is some confusion and conflicting opinions about ALH. Based on the best information available, it seems prudent to manage ALH the same as ADH.

6. What does it mean if my report mentions special studies such as high molecular weight cytokeratin (HMWCK), CK903, CK5/6, p63, muscle specific actin, smooth muscle myosin heavy chain, calponin, or keratin?

These are special tests that the pathologist sometimes uses to help make the correct diagnosis of a variety of breast lesions. Whether your report does or does not mention these tests has no bearing on the accuracy of your diagnosis.

7. What does it mean if my report also says any of the following terms: “usual duct hyperplasia”, “lobular hyperplasia”, “adenosis”, “sclerosing adenosis”, “radial scar”, “complex sclerosing lesion”, “papillomatosis”, “papilloma”, “apocrine metaplasia”, “cysts”, “columnar cell change”, “collagenous spherulosis”, “duct ectasia”, “fibrocystic changes”, “flat epithelial atypia”, or “columnar cell change with prominent apical snouts and secretions (CAPSS)”?

Most of these terms refer to benign growth patterns that have little or no influence on your health. However, there are certain benign conditions diagnosed by core needle biopsy that should prompt a discussion about doing an open surgical biopsy to make sure there is no cancer nearby. These include: Atypical Ductal Hyperplasia (including flat epithelial atypia), Atypical Lobular Hyperplasia, Lobular Carcinoma in situ, complex sclerosing lesion (also known as radial scar), papilloma (especially papilloma with atypia), and mucocele-like lesion.

8. What does it mean if my report mentions “microcalcifications” or “calcifications”?

“Microcalcifications” or “calcifications” are minerals that are found in both noncancerous and cancerous breast lesions and can be seen both on mammograms and under the microscope. They are reported by the pathologist to show that the abnormal area with calcifications seen on the mammogram was successfully sampled by the biopsy. Without accompanying worrisome changes in the breast ducts or lobules, “microcalcifications” or “calcifications” alone have no significance.

Navigate our Pathology FAQs and Images

  1. Benign Breast FAQ
  2. Benign Diseases - Atlas of Images
  3. Atypical Hyperplasia
  4. Breast Cancer In-Situ
  5. Breast Cancer
  6. Malignant Tumors - Atlas of Images
  7. Ask an Expert - Understanding Pathology Results

Authors: Jeanne Simpson (Vanderbilt Medical Center), Stuart Schnitt (Beth Israel Deaconess Medical Center), Jonathan I. Epstein (Johns Hopkins Medical Institutions)