The female breast is formed of 15–20 lobules of glandular tissue embedded in a variable amount of fat. The lobules are separated by fascial septa (ligaments of Cooper) that blend deeply with the investing layer of superficial fascia and, superficially, are attached to the overlying skin. The ducts from each lobule join to form a lactiferous duct that opens onto the nipple. The skin of the nipple and the surrounding areola is thin and pigmented, and contains a number of modified sebaceous glands (glands of Montgomery) and smooth muscle.
The base of the breast extends vertically from the second to the sixth ribs, and horizontally from the sternal edge to the midaxillary line (figure 1). It rests mainly on the pectoralis major muscle, but also laterally on the external oblique and serratus anterior muscles. An extension of breast tissue from the upper outer quadrant extends into the axilla (axillary tail).
The breast has subcutaneous and submammary lymphatic plexuses that drain mainly to the axillary lymph nodes. It may also drain directly to the infraclavicular nodes, nodes around the internal thoracic artery, lymphatics over the abdominal wall and to the opposite breast.
The female breast undergoes extensive changes during life, particularly at the menarche and during parturition, and undergoes cyclical variation with menstruation; nodularity and cystic changes are therefore frequently encountered. Most lumps are benign and nodularity, discomfort and tenderness are common symptoms, and often bilateral. However, cancer of the breast may present with similar signs, and it is essential to ensure early diagnosis and treatment of this common female malignancy. A rise in public awareness of the need to treat early breast malignancy has prompted self-examination and attendance at screening programmes. Patients with breast cancer usually present with a lump (figure 2), but pain and nipple discharge are important symptoms to fully investigate.
Take a full menstrual history, noting pregnancies, breast feeding, use of the pill and hormone replacement. Ask about previous lumps, their management and any family history of breast malignancy. The most important genetic link is premenstrual malignancy in a first degree relative. A persistent or progressive lump requires further investigation, possibly with mammography or needle aspiration. Mammography can be diagnostic of benign or malignant disease, while aspiration may remove both the cyst and the accompanying anxiety (figure 3). A fine needle aspirate from solid lessons is examined histologically. A subsequent diagnosis of malignancy allows patient involvement in the planned intervention.
Progression of local malignancy gives rise to skin and deep tethering, nipple inversion and, when more extensive, skin ulceration. There may also be spread to local lymph nodes and metastases, particularly to bone, liver and lungs, these areas are a routine part of the physical examination of breast disease.
The commonest nipple discharge is milk and this may persist after pregnancy or present at other times (galactorrhea), such as with endocrine abnormalities. Green or yellow discharge is often associated with cystic disease of the breast, blood staining may accompany benign or malignant lesions and the cause must always be identified.
Other abnormalities include breast infection, and supernumerary breasts and nipples along the milk line (from the axilla to the symphysis pubis). Although the male breast is rudimentary, it is subject to the same range of diseases as the female.