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The breast is the tissue overlying the chest (pectoral) muscles. Women's breasts are made of specialized tissue that produces milk (glandular tissue) as well as fatty tissue. The amount of fat determines the size of the breast.
The milk-producing part of the breast is organized into 15 to 20 sections, called lobes. Within each lobe are smaller structures, called lobules, where milk is produced. The milk travels through a network of tiny tubes called ducts. The ducts connect and come together into larger ducts, which eventually exit the skin in the nipple. The dark area of skin surrounding the nipple is called the areola.
Connective tissue and ligaments provide support to the breast and give it its shape. Nerves provide sensation to the breast. The breast also contains blood vessels, lymph vessels, and lymph nodes.
- Breast cancer: Malignant (cancer) cells multiplying abnormally in the breast, eventually spreading to the rest of the body if untreated. Breast cancer occurs almost exclusively in women, although men can be affected. Signs of breast cancer include a lump, bloody nipple discharge, or skin changes.
- Ductal carcinoma in situ (DCIS): Breast cancer in the duct cells that has not invaded deeper or spread through the body. Women diagnosed with DCIS have a high likelihood of being cured.
- Lobular carcinoma in situ (LCIS): Although called a carcinoma LCIS, which occurs in the milk-producing lobule cells, does not invade or spread and is not a true cancer. However, women with LCIS have an increased likelihood of developing invasive breast cancer in the future.
- Invasive ductal carcinoma: Breast cancer that begins in the duct cells but then invades deeper into the breast, carrying the potential of spreading to the rest of the body (metastasizing). Invasive ductal carcinoma is the most common type of invasive breast cancer.
- Invasive lobular carcinoma: Breast cancer that begins in the milk-producing lobule cells, but then invades deeper into the breast, carrying the potential of spreading to the rest of the body (metastasizing). Invasive lobular carcinoma is an uncommon form of breast cancer.
- Simple breast cyst: A benign (noncancerous), fluid-filled sac that commonly develops in women in their 30s or 40s. Breast cysts may cause tenderness and may be drained.
- Breast fibroadenoma: A very common noncancerous solid tumor of the breast. A typical fibroadenoma creates a painless, mobile lump in the breast and most commonly occurs in women in their 20s or 30s.
- Fibrocystic breast disease: A common condition in which noncancerous breast lumps may become uncomfortable and change in size throughout the menstrual cycle.
- Usual hyperplasia of the breast: A breast biopsy may show normal-appearing, noncancerous ductal cells multiplying abnormally. The presence of usual hyperplasia may slightly increase a woman's lifetime risk of breast cancer.
- Atypical hyperplasia of the breast: Abnormal-appearing cells multiplying either in the breast ducts (atypical ductal hyperplasia) or lobules (atypical lobular hyperplasia), sometimes discovered by a breast biopsy. Although the condition is noncancerous, women with atypical hyperplasia are at four to five times higher risk of developing breast cancer compared to women with no breast abnormalities.
- Intraductal papilloma: A noncancerous, wart-like breast mass that grows inside the breast ducts. Intraductal papillomas may be felt as a lump or cause clear or bloody fluid to leak from the nipple.
- Adenosis of the breast: A noncancerous enlargement of the breast lobules. Adenosis can look like breast cancer on mammograms, so a biopsy may be needed to rule out breast cancer.
- Phyllodes tumor: A rare, usually large, rapidly growing breast tumor that looks like a fibroadenoma on ultrasound. Phyllodes tumors may be benign or malignant and most commonly develop in women in their 40s.
- Fat necrosis: In response to an injury in the fatty part of the breast, a lump of scar tissue may develop. This mass can seem like breast cancer on examination or in mammograms.
- Mastitis: Inflammation of the breast, causing redness, pain, warmth, and swelling. Nursing mothers are at higher risk for mastitis, which is usually the result of infection.
- Breast calcifications: Calcium deposits in the breast are a common finding on mammograms. The pattern of calcium might suggest cancer, leading to further tests or a biopsy.
- Gynecomastia: Overdevelopment of male breasts. Gynecomastia can affect newborns, boys, and men.
- Physical Exam: By examining the breast and nearby underarm tissue for lumps, skin changes, nipple discharge, or lymph nodes, a doctor can find any abnormalities in the breast. Characteristics of breast lumps, such as size, shape, texture, are usually noted.
- Mammogram: A mammography machine compresses each breast and takes low-dose X-rays. Mammograms are the most commonly used test for early detection, or screening, for breast cancer.
- Digital mammogram: A mammogram that stores the electronic images of each breast in a digital, computer-readable format. This is different than a standard film mammogram, where the images are created directly on film.
- Diagnostic mammogram: Additional mammogram views beyond those done in a routine mammogram may sometimes be necessary to evaluate an abnormal mammogram or a breast abnormality.
- Breast ultrasound: A device placed on the skin bounces high-frequency sound waves through breast tissue. The signals are converted into pictures on a video screen, allowing health care providers to see structures inside the body. Breast ultrasound can often determine whether a lump is made of fluid (cyst) or solid material.
- Breast magnetic resonance imaging (MRI scan): An MRI scanner uses a high-powered magnet and a computer to create detailed images of the breast and surrounding structures. Breast MRIs can add additional information to mammograms and are recommended only in specific cases.
- Breast biopsy: A small sample of tissue is taken from an abnormal-appearing area of the breast that is seen on physical exam, mammogram, or other imaging study and examined for cancer cells. A biopsy may be done with a needle or with minor surgery.
- Fine needle aspiration (FNA) breast biopsy: A doctor inserts a thin needle into an abnormal-appearing area of the breast and draws out (aspirates) fluid and breast tissue. This is the simplest type of biopsy and is mostly used for lumps that can be easily felt in the breast.
- Core needle breast biopsy: A larger, hollow needle is inserted into a breast mass, and a tube-shaped piece of breast tissue (core) is drawn out. A core biopsy provides more breast tissue for evaluation than an FNA biopsy.
- Stereotactic breast biopsy: A breast biopsy in which computerized pictures help the health care provider reach the exact location of the abnormal breast tissue to remove a sample.
- Surgical biopsy: Surgery may be recommended to take out part or all of a breast lump to check for cancer.
- Sentinel node biopsy: A type of biopsy in which the health care provider locates and removes the lymph node(s) that the primary tumor is most likely to spread. This type of biopsy helps determine the likelihood that a cancer has spread.
- Ductogram (galactogram): A thin plastic tube is inserted into a duct in the nipple, and contrast dye is injected into the breast to help the health care provider view the breast ducts. A ductogram can help identify the cause of bloody nipple discharge.
- Nipple smear (nipple discharge exam): A sample of bloody or abnormal fluid leaked from the nipple is examined under the microscope to see if any cancer cells are present.
- Ductal lavage: Sterile water is injected into the nipple ducts, then collected and examined for cancer cells. This experimental test is only used in women known to be at high risk for breast cancer.
- Lumpectomy: Surgery to remove a breast lump (which may be breast cancer) and some normal tissue surrounding it. Many early breast cancers are surgically removed by lumpectomy rather than mastectomy.
- Mastectomy: Surgery to remove the entire breast. In a radical mastectomy, some of the chest wall muscle and surrounding lymph nodes are also removed.
- Axillary lymph node dissection: Surgical removal of armpit lymph nodes, which may be affected by breast cancer. These lymph nodes are the gateway for cancer cells to spread to the rest of the body.
- Chemotherapy: Medicine taken as pills or given through the veins to kill cancer cells. Chemotherapy may be given to reduce the size of a cancer or to reduce its chance of spreading or returning.
- Radiation therapy: High-energy radiation waves directed by a machine at the breast, chest wall, and armpit can kill remaining cancer cells after surgery (external beam radiation). Radiation may also be delivered by placing radioactive material inside your body (brachytherapy).
- Breast reconstruction: When an entire breast or large amounts of breast tissue are removed, such as after a mastectomy, the breast can be reconstructed using either an implant or tissue from your own body.
- Antibiotics: In cases of mastitis caused by bacteria, antibiotics can usually cure the infection.
- Breast augmentation: Surgery to increase the size or improve the shape of the breasts, using artificial implants.
- Breast reduction: Surgery to reduce the size of breasts. In women, this is often done to relieve neck or back pain from exceptionally large breasts. Men may also seek breast reduction for gynecomastia.