CHAPTER 10: The Breasts and Axillae


Anatomy and Physiology

The Female Breast

The female breast lies against the anterior thoracic wall, extending from the clavicle and 2nd rib down to the 6th rib, and from the sternum across to the midaxillary line. Its surface area is generally rectangular rather than round (Fig. 10-1).

FIGURE 10-1 The female breast.

The female breast.

The breast overlies the pectoralis major and, at its inferior margin, the serratus anterior.

To describe clinical findings, the breast is often divided into four quadrants based on horizontal and vertical lines crossing at the nipple (Fig. 10-2). A fifth area, an axillary tail of breast tissue, sometimes termed the “tail of Spence,” extends laterally across the anterior axillary fold. Alternatively, findings can be localized as the time on the face of a clock (e.g., 3 o’clock) and the distance in centimeters from the nipple.

FIGURE 10-2 Breast quadrants.

Breast quadrants.

The breast is a hormonally sensitive tissue, responsive to the changes of monthly cycling and aging. Glandular tissue, consisting of milk-secreting tubuloalveolar glands and ductules, forms 15 to 20 septated lobes radiating around the nipple (Fig. 10-3). Within each lobe are many smaller lobules. The glandular tissue within each lobule drains into larger collecting ducts and lactiferous sinuses leading to 5 to 10 porous openings on the surface of the areola and the nipple.

Fibrous connective tissue provides structural support in the form of fibrous bands or suspensory ligaments, also known as Cooper ligaments, connected to both the skin and the underlying fascia. Adipose tissue, or fat, surrounds the breast, predominantly in the superficial and peripheral areas. The proportions of these components vary with age, nutritional status, pregnancy, exogenous hormone use, and other factors. After menopause, there is atrophy of glandular tissue, and a notable decrease in the number of lobules.

FIGURE 10-3 Breast anatomy.

Breast anatomy.

The surface of the areola has small, rounded elevations formed by sebaceous glands, sweat glands, and accessory areolar glands (Fig. 10-4). A few hairs are often seen on the areola. During pregnancy, the sebaceous glands produce an oily secretion that serves as a protective lubricant for the areola and nipple during lactation.

FIGURE 10-4 Nipple and areola.

Nipple and areola.

Both the nipple and the areola are supplied with smooth muscle that contracts to express milk from the ductal system during breast-feeding. Rich sensory innervation, especially in the nipple, triggers “milk letdown” following neurohormonal stimulation from infant sucking. Tactile stimulation of the area, including the breast examination, makes the nipple smaller, firmer, and more erect, whereas the areola puckers and wrinkles. These smooth muscle reflexes are normal and should not be mistaken for signs of breast disease.

The adult breast may be soft, but it often feels granular, nodular, or lumpy. This uneven texture is normal physiologic nodularity. It is often bilateral and may occur throughout the breast or only in some areas. The nodularity may increase before menses, a time when breasts often enlarge and become tender or even painful. For breast changes during adolescence and pregnancy, see pp. 896–897 and p. 928.

Occasionally, one or more extra or supernumerary nipples are located along the “milk line,” illustrated in Figure 10-5. Usually, only a small nipple and areola are present, often mistaken for a common mole. Those containing glandular tissue occasionally show increased pigmentation, swelling, tenderness, or even lactation during puberty, menstruation, or pregnancy. Possible associations with renal, urogenital, and cardiovascular disorders are under current investigation, but treatment is only needed if there is diagnostic ambiguity, cosmetic concerns, or possible pathology.[1]

FIGURE 10-5 Milk lines.

Milk lines.

The Male Breast

The male breast consists chiefly of a small nipple and areola overlying a thin disc of undeveloped breast tissue consisting primarily of ducts. Lacking estrogen and progesterone stimulation, ductal branching and development of lobules are minimal,[2],[3] making it difficult to distinguish male breast tissue from the surrounding muscles of the chest wall. There is a firm button of breast tissue 2 cm or more in diameter in roughly one of three adult men.

Some men develop benign breast enlargement from gynecomastia, a proliferation of palpable glandular tissue, or pseudogynecomastia, the accumulation of subareolar fat. Causes of gynecomastia include increased estrogen, decreased testosterone, and medication side effects.4


Most lymphatic vessels of the breast drain into the axillary lymph nodes (Fig. 10-6). Of these, the central nodes are the most likely to be palpable. They lie along the chest wall, usually high in the axilla and midway between the anterior and posterior axillary folds. Three other groups of lymph nodes drain into the central nodes and are seldom palpable:

FIGURE 10-6 Direction of lymph flow.

Direction of lymph flow.

? Pectoral nodes—anterior, located along the lower border of the pectoralis major inside the anterior axillary fold. These nodes drain the anterior chest wall and much of the breast.
? Subscapular nodes—posterior, located along the lateral border of the scapula; palpated deep in the posterior axillary fold. They drain the posterior chest wall and a portion of the arm.
? Lateral nodes—located along the upper humerus. They drain most of the arm.

Lymph drains from the central axillary nodes to the infraclavicular and supraclavicular nodes.

Not all the lymphatics of the breast drain into the axilla. Malignant cells from a breast cancer may spread directly to the infraclavicular nodes or into the internal mammary chain of lymph nodes within the chest.

The Health History

Common or Concerning Symptoms

  • Breast lump or mass
  • Breast discomfort or pain
  • Nipple discharge

You can elicit concerns about the breasts during the history or later during the physical examination. Ask if the patient has had any lumps, discomfort, or pain in her breasts. About 50% of women have palpable lumps or nodularity, and premenstrual enlargement and tenderness are common.[5],[6] If your patient reports a lump or mass, identify the precise location, how long it has been present, and any change in size or variation within the menstrual cycle. Ask if there has been any change in breast contour, dimpling, swelling, or puckering of the skin over the breasts.

Lumps may be physiologic or pathologic, ranging from cysts and fibroadenomas to breast cancer. See Table 10-1, Common Breast Masses, p. 444, and Table 10-2, Visible Signs of Breast Cancer, p. 445.

TABLE 10-1 Common Breast Masses

The three most common breast masses are fibroadenoma (a benign tumor), cysts, and breast cancer. The clinical characteristics of these masses are listed below. However,
any breast mass should be carefully evaluated and usually warrants further investigation by ultrasound, aspiration, mammography, or biopsy.
The masses depicted below are large for purposes of illustration. Fibrocystic changes, not illustrated, are also commonly palpable as nodular, rope-like densities in women aged 25 to 50 years. They may be tender or painful. They are considered benign and not a risk factor for breast cancer.
Fibroadenoma Cysts Cancer
Image not available Image not available Image not available
Usual Age (in Years) 15–25 years, usually puberty and young adulthood, but up to age 55 years 30–50 years, regress after menopause except with estrogen therapy 30–90 years, most common over age 50 years
Number Usually single, may be multiple Single or multiple Usually single, although may coexist with other nodules
Shape Round, disclike, or lobular; typically small (1–2 cm) Round Irregular or stellate
Consistency May be soft, usually firm Soft to firm, usually elastic Firm or hard
Delimitation Well delineated Well delineated Not clearly delineated from surrounding tissues
Mobility Very mobile Mobile May be fixed to skin or underlying tissues
Tenderness Usually nontender Often tender Usually nontender
Retraction Signs Absent Absent May be present

TABLE 10-2 Visible Signs of Breast Cancer

Image not available

Retraction Signs

As breast cancer advances, it causes fibrosis (scar tissue). Shortening of this tissue produces dimpling, changes in contour, and retraction or deviation of the nipple. Other causes of retraction include fat necrosis and mammary duct ectasia.

Image not available

Abnormal Contours

Look for any variation in the normal convexity of each breast, and compare one side with the other. Special positioning may again be useful. Shown here is marked flattening of the lower outer quadrant of the left breast.

Image not available

Skin Dimpling

Look for this sign with the patient’s arm at rest, during special positioning, and on moving or compressing the breast, as illustrated here.

Image not available

Nipple Retraction and Deviation

A retracted nipple is flattened or pulled inward, as illustrated here. It may also be broadened, and feels thickened. When involvement is radially asymmetric, the nipple may deviate or point in a different direction from its normal counterpart, typically toward the underlying cancer.

Image not available

Edema of the Skin

Edema of the skin is produced by lymphatic blockade. It appears as thickened skin with enlarged pores—the so-called peau d’orange (orange peel) sign. It is often seen first in the lower portion of the breast or areola.

Image not available

Paget Disease of the Nipple

This uncommon form of breast cancer usually starts as a scaly, eczema-like lesion on the nipple that may weep, crust, or erode. A breast mass may be present. Suspect Paget disease in any persisting dermatitis of the nipple and areola. Often (;60%) presents with an underlying in situ or invasive ductal or lobular carcinoma.

Breast pain, or mastalgia, is the most common breast symptom prompting office visits. Breast pain alone (without mass) is not considered a breast cancer risk factor. Determine if the pain is diffuse or focal, cyclic or noncyclic, and related to medications.

Clinical breast examination (CBE) is warranted. Focal breast pain is more likely to merit diagnostic imaging. Medications associated with breast pain include hormonal therapy; psychotropic drugs such as selective serotonin reuptake inhibitors and haloperiodol; spironolactone, and digoxin.6

Ask about any discharge from the nipples and when it occurs. Does the discharge appear only after compression of the nipple, or is it spontaneous? Physiologic hypersecretion is seen in pregnancy, lactation, chest wall stimulation, sleep, and stress. If spontaneous, what is the color, consistency, and quantity? Is the color milky, brown or greenish, or bloody? Ask if the discharge is unilateral or bilateral. Physiologic discharge is usually bilateral, multiductal, prompted by stimulation, and ranges in color from white to yellowish or green.

Galactorrhea, or the discharge of milk-containing fluid unrelated to pregnancy or lactation, is more likely to be pathologic when it is bloody or serous, unilateral, spontaneous, associated with a mass, and occurring in women aged ?40 years.6

Health Promotion and Counseling: Evidence and Recommendations

Important Topics for Health Promotion and Counseling

  • Palpable masses of the breast
  • Assessing risk of breast cancer
  • Breast cancer screening

Women may experience a wide range of changes in breast tissue and sensation, from cyclic swelling and nodularity to a distinct lump or mass. The examination of the breast is an important opportunity for exploring key concerns for women’s health—what to do if a lump or mass is detected, risk factors for breast cancer, and screening measures such as breast self-examination (BSE), the CBE by a skilled clinician, and mammography.

Palpable Masses of the Breast and Breast Symptoms

Breast cancer occurs in up to 4% of women with breast complaints, in approximately 5% of women reporting a nipple discharge, and in up to 11% of women specifically complaining of a breast lump or mass.[3],[5] Breast masses show marked variation in etiology, from fibroadenomas and cysts seen in younger women, to abscess or mastitis, to primary breast cancer. On initial assessment, the woman’s age and the physical characteristics of the mass provide clues about etiology, as shown below, but definitive diagnosis should be pursued and often requires further evaluation with ultrasound, mammography, or even biopsy.

Palpable Masses of the Breast

Age (in Years) Common Lesion Characteristics
15–25 Fibroadenoma Usually smooth, rubbery, round, mobile, nontender
25–50 Cysts Usually soft to firm, round, mobile; often tender
Fibrocystic changes Nodular, ropelike
Cancer Irregular, firm, may be mobile or fixed to surrounding tissue
Over 50 Cancer until proven otherwise As above
Pregnancy/lactation Lactating adenomas, cysts, mastitis, and cancer As above

Adapted from Schultz MZ, Ward BA, Reiss M. Breast diseases. In: Noble J, Greene HL, Levinson W (eds). Primary Care Medicine, 2nd ed. St. Louis: MO; 1996; Venet L, Strax P, Venet W Adequacies and inadequacies of breast examinations by physicians in mass screenings. Cancer. 1971;28:1546.

Assessing Risk of Breast Cancer

Women are increasingly interested in learning about breast cancer. Be familiar with the literature about breast cancer risk factors that support recommendations for screening. Key facts and figures are presented here, but further reading will enhance your counseling of female patients.

Breast Cancer Facts and Figures

Breast cancer is the most common cause of cancer in women worldwide, accounting for more than 10% of cancers in women. In the United States, a woman born now has a 12%, or 1 in 8, lifetime risk of developing breast cancer.[7] Eighty percent of new breast cancer cases occur after age 50 years, with a median age at diagnosis of age 61 years. The probability of diagnosis increases with each decade.

Age-Specific Probabilities of Developing Invasive Female Breast Cancera

If Current Age is: The Probability of Developing Breast Cancer in the Next 10 Years is: Or 1 in:
20 0.1% 1,674
30 0.4% 225
40 1.4% 69
50 2.3% 44
60 3.5% 29
70 3.9% 26
Lifetime Risk 12.3% 8

Source: American Cancer Society. Breast Cancer Facts and Figures 2013–2014, p 17. Available at Accessed May 1, 2015. Updated to 2015–2016, © 2015.

Breast cancer is the second leading cause of cancer death in women following lung cancer.[7] Five-year survival rates are 99% for local disease, 84% for regional disease, and 24% for metastatic disease. In its annual report, Breast Cancer Facts and Figures 2013–2014, the American Cancer Society highlights important trends in breast cancer statistics.

? Relatively stable incidence rates since 2004. Incidence dropped 7% in 2002–2003, attributed to declining use of hormone replacement therapy (HRT). Subsequent incidence rates have been relatively stable, with a small increase between 2006 and 2010 in both white (0.1%) and African American (0.2%) women.

? Declining death rates overall, but more advanced disease and higher mortality in African American women. Compared to white women, African American women have a higher incidence of breast cancer before age 40 years, are more likely to have larger and estrogen receptor (ER)–negative tumors at the time of diagnosis, and are more likely to die of breast cancer at every age. Although overall breast cancer death rates decreased by 34%, or 1.6% per year, between 1990 and 2010, in 2010 African American women still had a 41% higher mortality rate than white women. This major health disparity is attributed to differences in use of mammography, more aggressive tumor characteristics, access to and response to new treatments, and the presence of coexisting illnesses.