The breast is made up of glands that can produce milk, ducts that carry milk to the nipple, and supporting fatty and fibrous tissue. A wide range of changes can develop in the breast, and most are not cancer. When tissue is removed from the breast, a pathologist examines it under a microscope and describes what they see in your pathology report.
This page brings together our guides to conditions found in the breast. The articles are grouped by type to help you find the one that matches your diagnosis. Select any article below to learn more.
Cancers of the breast
These diagnoses are types of breast cancer. Most are invasive, meaning the cancer cells have grown beyond the ducts or glands into the surrounding breast tissue. The articles explain how each type is diagnosed and what the details in your pathology report mean.
Invasive breast carcinoma is the general name for cancer that has grown into the breast tissue beyond the ducts or glands. This article gives an overview of the diagnosis, including the different types and what your pathology report describes.
You may find this helpful if your report mentions invasive breast carcinoma, or you want a general overview before reading about a specific type.
Invasive ductal carcinoma is the most common type of invasive breast cancer. It begins in a duct and grows into the surrounding tissue. This article explains how it is diagnosed and what your report describes.
You may find this helpful if your report says invasive ductal carcinoma, or invasive carcinoma of no special type.
Invasive lobular carcinoma is the second most common type of invasive breast cancer. It begins in the milk-producing glands and grows in a distinctive pattern. This article explains what this diagnosis means.
You may find this helpful if your report says invasive lobular carcinoma of the breast.
Invasive mammary carcinoma is a term used for invasive breast cancer that has features of both the ductal and lobular types. This article explains what this diagnosis means and what your report describes.
You may find this helpful if your report mentions invasive mammary carcinoma, or a cancer with mixed ductal and lobular features.
Invasive mucinous carcinoma is a type of invasive breast cancer in which the cancer cells are surrounded by mucus. It is usually slow-growing. This article explains what this diagnosis means.
You may find this helpful if your report mentions mucinous carcinoma of the breast.
Invasive apocrine carcinoma is a type of invasive breast cancer made of cells that resemble the cells of sweat glands. This article explains what this diagnosis means and what your report describes.
You may find this helpful if your report mentions invasive apocrine carcinoma of the breast.
Invasive ductal carcinoma with apocrine features
This is a type of invasive ductal carcinoma in which some cancer cells resemble sweat gland cells. This article explains what this diagnosis means and what your report describes.
You may find this helpful if your report mentions invasive ductal carcinoma with apocrine features.
Metaplastic carcinoma is an uncommon type of invasive breast cancer in which the cancer cells have changed into a different cell type. This article explains how it is diagnosed and what your report describes.
You may find this helpful if your report mentions metaplastic carcinoma of the breast.
Secretory carcinoma is a rare, usually slow-growing type of invasive breast cancer defined by a specific gene change. This article explains what this diagnosis means.
You may find this helpful if your report mentions secretory carcinoma of the breast.
Encapsulated papillary carcinoma
Encapsulated papillary carcinoma is a slow-growing breast cancer that grows within a clear border inside a cyst-like space. It has an excellent outlook. This article explains what this diagnosis means.
You may find this helpful if your report mentions encapsulated papillary carcinoma, sometimes shortened to EPC.
Paget disease of the breast is a type of breast cancer that involves the skin of the nipple. It is often linked to another breast cancer underneath. This article explains what this diagnosis means.
You may find this helpful if your report mentions Paget disease of the nipple, or you have a scaly, red change of the nipple.
Noninvasive and precancerous changes
These diagnoses describe changes in the breast that are not invasive cancer. Some are an early, non-invasive form of cancer that has not spread beyond the ducts. Others are precancerous, meaning they are not cancer but can increase the risk that cancer develops later. The articles explain what each diagnosis means.
Ductal carcinoma in situ is an early, non-invasive breast cancer. The cancer cells are still contained within the ducts and have not spread into the surrounding tissue. This article explains what this diagnosis means.
You may find this helpful if your report mentions ductal carcinoma in situ or DCIS.
Lobular carcinoma in situ is a change in the milk-producing glands of the breast. Despite its name, it is not cancer, but it is a sign of an increased risk of breast cancer. This article explains what this diagnosis means.
You may find this helpful if your report mentions lobular carcinoma in situ or LCIS.
Atypical ductal hyperplasia is a precancerous change in which abnormal cells build up inside a breast duct. It is not cancer, but it increases the risk of breast cancer. This article explains what this diagnosis means.
You may find this helpful if your report mentions atypical ductal hyperplasia or ADH.
Atypical lobular hyperplasia is a precancerous change in the milk-producing glands of the breast. It is not cancer, but it increases the risk of breast cancer. This article explains what this diagnosis means.
You may find this helpful if your report mentions atypical lobular hyperplasia or ALH.
Flat epithelial atypia is an early change in which the cells lining a breast duct look mildly abnormal. It is not cancer, but it is sometimes found alongside other changes that need follow-up. This article explains what this diagnosis means.
You may find this helpful if your report mentions flat epithelial atypia or FEA.
Noncancerous changes and growths
These diagnoses are not cancer. They include common benign changes in the breast tissue as well as noncancerous growths. Many are found by chance during testing for another reason. The articles explain what each diagnosis means.
A fibroadenoma is a common, noncancerous breast tumor. It is the most common breast lump in young women. This article explains what this diagnosis means and how it is treated.
You may find this helpful if your report mentions a fibroadenoma, or you have a smooth, movable breast lump.
An intraductal papilloma is a small, noncancerous growth that develops inside a breast duct. It can sometimes cause nipple discharge. This article explains what this diagnosis means.
You may find this helpful if your report mentions an intraductal papilloma, or you have had clear or bloody nipple discharge.
Fibrocystic change is a very common, noncancerous condition that can make the breast feel lumpy or tender. This article explains what this diagnosis means and what a pathologist looks for.
You may find this helpful if your report mentions fibrocystic change, or you have lumpy or tender breasts.
Sclerosing adenosis is a noncancerous condition in which the milk-producing glands become enlarged and scarred. This article explains what this diagnosis means.
You may find this helpful if your report mentions sclerosing adenosis of the breast.
A radial scar is a noncancerous change with a star-like shape that can look like cancer on a mammogram. This article explains what this diagnosis means and why it is sometimes removed.
You may find this helpful if your report mentions a radial scar or a radial sclerosing lesion.
A complex sclerosing lesion is a larger form of radial scar. It is a noncancerous change that can look like cancer on imaging. This article explains what this diagnosis means.
You may find this helpful if your report mentions a complex sclerosing lesion.
Columnar cell change is a common, noncancerous change in the cells lining the milk-producing glands of the breast. This article explains what this diagnosis means.
You may find this helpful if your report mentions columnar cell change or CCC.
Columnar cell hyperplasia is a noncancerous change in which there is an increased number of cells lining the milk-producing glands. This article explains what this diagnosis means.
You may find this helpful if your report mentions columnar cell hyperplasia or CCH.
Usual ductal hyperplasia is a common, noncancerous change in which extra cells build up inside a breast duct. It does not meaningfully increase the risk of breast cancer. This article explains what this diagnosis means.
You may find this helpful if your report mentions usual ductal hyperplasia.
Pseudoangiomatous stromal hyperplasia
Pseudoangiomatous stromal hyperplasia is a noncancerous overgrowth of the supporting tissue of the breast. This article explains what this diagnosis means.
You may find this helpful if your report mentions pseudoangiomatous stromal hyperplasia or PASH.
Phyllodes tumors
Phyllodes tumors are a family of breast tumors that grow from the supporting tissue of the breast. They range from noncancerous to cancerous. The articles explain how each type is diagnosed and what your pathology report describes.
Phyllodes tumor is the general name for a group of breast tumors that range from noncancerous to cancerous. This article gives an overview of the diagnosis, including the different types and what your report describes.
You may find this helpful if your report mentions a phyllodes tumor, or you want a general overview before reading about a specific type.
A benign phyllodes tumor is the noncancerous type of phyllodes tumor. It can grow quickly but does not spread to other parts of the body. This article explains what this diagnosis means.
You may find this helpful if your report mentions a benign phyllodes tumor.
A borderline phyllodes tumor falls between the benign and malignant types. It is more likely than a benign phyllodes tumor to come back after treatment. This article explains what this diagnosis means.
You may find this helpful if your report mentions a borderline phyllodes tumor.
A malignant phyllodes tumor is the cancerous type of phyllodes tumor. It can grow quickly and, less often, spread to other parts of the body. This article explains what this diagnosis means.
You may find this helpful if your report mentions a malignant phyllodes tumor.
Diagnoses that need further testing
These are general terms a pathologist uses when a breast lesion has been found on a small biopsy sample but its exact type cannot yet be determined. Removing the whole lesion is usually needed to make a final diagnosis. The articles explain what these terms mean.
Papillary lesion is a general term for a group of breast growths that form finger-like shapes. They range from noncancerous to cancerous, so further testing is often needed. This article explains what this term means.
You may find this helpful if your report or biopsy result mentions a papillary lesion of the breast.
Fibroepithelial lesion is a general term used when a breast tumor is made of both gland and supporting tissue, but it is not yet clear whether it is a fibroadenoma or a phyllodes tumor. This article explains what this term means.
You may find this helpful if your report or biopsy result mentions a fibroepithelial lesion.
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