Breast Diseases

To understand breast conditions, it is necessary to appreciate the distinct tissues that make up the breast. The breast is composed primarily of glandular tissues and supporting, or stromal, tissues. The glandular part of the breast includes the lobules, which produce milk, and the ducts, which carry the milk from the lobules to the nipple. The stromal tissue includes fatty, or adipose, tissue and fibrous connective tissue, which is made up of ligaments that support the breast. Breast diseases are a wide spectrum of diseases ranging from benign fibromas to cancerous tumors associated with varying prognoses. Although certain diseases such as melanoma [Page 305]and lymphomas may ultimately spread to the breast and other organs, the term breast diseases refers to disorders of the breast that first arise in the breast.

Benign breast diseases include a range of disorders that can cause breast pain, lumps, or nipple discharge in a patient of any age. The most common cause of benign nodularity, or lumpiness, and pain in the breast is fibrocystic change, followed by benign breast tumors and breast inflammation. Fibrocystic change is a hormonally related process that occurs in about 60 percent of premenopausal women and usually does not involve nipple discharge. Fibrocystic changes can be grouped into either epithelial hyperplasia, or overgrowth of cells lining the duct or lobule, or adenosis, which is enlargement of the lobules. The most common cause of a benign breast mass with possible discharge is a fibroadenoma. Other benign causes of breast pain, nodularity, and nipple discharge include breast abscesses and mastitis, infections of the breast tissue that often occur during breastfeeding, and naturally large pendulous breasts. Far less common causes include duct ectasia, sclerosing adenosis, phyllodes tumors, intraductal papillomas, fat necrosis, breast masses, and hidradenitis suppurativa.

Keys to distinguishing among the possible causes of benign breast disease include careful history and examination of the lesion. Infectious causes are usually revealed by localized inflammation, warmth, and discharge. However, fibroadenomas can sometimes present more like cancerous breast masses and often require ultrasound imaging and biopsy to rule out cancer. Although benign breast conditions are by definition not cancerous, they can cause troubling symptoms and over time can increase a patient's risk of developing breast cancer.

The two main tests used to image questionable masses in the breast include mammograms and ultrasound. Mammograms are X-rays of the breast tissue that allow visualization of masses or calcifications. Macrocalcifications are usually due to deposits of cal-cium-rich plaques in the arteries due to aging and are considered benign. Microcalcifications are finer calcifications that can be suspicious for a cancerous or precancerous process depending on the distribution of the calcifications. Ultrasounds are useful in helping to determine if a mass is cystic, or fluid-filled, or solid. In most cases, it is not necessary to biopsy cysts, but masses usually require tissue biopsy to rule out cancer. Other diagnostic tests that may be performed are pathological analysis of breast nipple discharge and fine needle aspiration or core biopsies.

Cancerous breast diseases include a spectrum of diseases and can present in many different ways. They differ from benign breast diseases because they have grown enough to invade surrounding tissues. The most common types of breast tumors are invasive adenocarcinomas, which are cancers of glandular tissue and can be divided into ductal or lobular adenocarcinomas. Precursor forms of these lesions that have not yet begun to invade beyond the duct or breast are referred to as ductal carcinoma in situ (DCIS) and lobular carcinoma in situ (LCIS). About 20 percent of new breast cancer cases are DCIS, while 80 percent are invasive ductal adenocarcinomas, and 10 percent are invasive lobular. Breast tumors can be further classified according to how the cells appear under the microscope to a trained pathologist, with medullary, tubular, and mucinous representing more benign types of tumors.

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