RADIOLOGY OF THE BREAST: INTRODUCTION

Imaging of the breast is undertaken as part of a comprehensive evaluation of this organ, integrating the patient's history, clinical signs, and symptoms. Radiographyof the breast is known as mammography or radiomammography. When used periodically in asymptomatic patients, this is called screening mammography. When imaging is targeted to patients with signs or symptoms of breast cancer, it is referred to as diagnostic breast imaging and usually is a tailored evaluation consisting of some combination of mammography and other techniques described in this chapter. Using the integrated approach, it is often possible to make an accurate diagnosis nonoperatively, and treatment may be individualized according to each patient's needs. The primary purpose of breast imaging is to detect breast carcinoma. A secondary purpose is to evaluate benign disease, such as cyst formation, infection, implant complication, and trauma.

Before the 1980s, when breast imaging was much less widely used, the proportion of surgery for benign breast disease was higher, and treatment for breast carcinoma was initiated at later stages of the disease than at present. Breast imaging has increased the detection of tumors smaller than those found on clinical breast examination and has enabled patients to avoid unnecessary surgery.

The outcome of earlier diagnosis and treatment, however, is yet to be proven. Mortality from breast cancer has remained fairly stable for several decades in spite of the introduction and popularization of screening mammography. Debate continues as to the efficacy of routine breast screening in certain age groups. It is almost universally acknowledged that women older than 50 years of age benefit from periodic screening mammography. Several large population studies have shown a decrease in mortality of around 30% in this group. The greatest current controversy concerns the value of screening mammography for women under the age of 50 years. Because breast cancer has a lower prevalence in this age group, the impediment to mass screening is largely economic; that is, the number of lives saved relative to dollars spent must be justified. Another difference is that in younger women the breast parenchyma is more often dense and nodular. This condition decreases the sensitivity for detection of carcinoma and leads to more false-negative and false-positive results.

Besides a decrease in mortality, a second benefit of earlier diagnosis is that patients with breast carcinoma are afforded more treatment options; lumpectomy with radiation therapy is an option to mastectomy in selected patients.

Mammography has been in common use since about 1980, and breast ultrasonography has been the most often used adjunctive technique during this time. The major contribution of ultrasonography has been its effectiveness in distinguishing cystic lesions from solid masses. Sonography has, therefore, helped to avoid unnecessary surgery, because asymptomatic simple cysts do not require intervention. Some practitioners also use ultrasonography, together with mammography, to help characterize solid lesions as benign, indeterminate, or suspicious.

Magnetic resonance (MR) imaging of the breast can be used in selected patients. Image-guided needle biopsy of the breast has become the first-line procedure for diagnosis of indeterminate lesions of the breast, with surgical biopsy being reserved for special cases. Nuclear medicine and contrast injection studies (ductography) are occasionally used under special circumstances with specific indications.

TECHNIQUE AND NORMAL ANATOMY

Film-Screen and Digital Radiography (Radiomammography)

The film-screen mammogram is created with x-rays, radiographic film, and intensifying screens adjacent to the film within the cassette, hence the term film-screen mammography. The digital mammogram is created using a similar system, but replacing the film and screen with a digital detector.

The routine examination consists of two views of each breast, the craniocaudal (C-C) view and the mediolateral oblique (MLO) view, with a total of four films. The C-C view can be considered the "top down" view, and the MLO an angled view from the side (Figs. 5–1 and 5–2). The patient undresses from the waist up and stands for the examination, leaning slightly against the mammography unit. The technologist must mobilize, elevate, and pull the breast to place as much breast tissue as possible on the surface of the film cassette holder. A flat, plastic compression paddle is then gently but firmly lowered onto the breast surface to compress the breast into as thin a layer as possible. This compression achieves both immobilization during exposure and dispersion of breast tissue shadows over a larger area, thereby permitting better visual separation of imaged structures. Compression may be uncomfortable, and may even be painful in a small proportion of patients. However, most patients accept this level of discomfort for the few seconds required for each exposure, particularly if they understand the need for compression and know what to expect during the examination. Mammography has proved to be more cost effective, while maintaining resolution high enough to demonstrate early malignant lesions, than any other breast imaging technique. In its present state of evolution, the sensitivity of radiomammography ranges from 85% to 95%.

LIMITATIONS

Sensitivity is limited by three factors: (1) the nature of breast parenchyma, (2) the difficulty in positioning the organ for imaging, and (3) the nature of breast carcinoma.

The Nature of Breast Parenchyma.

Very dense breast tissue may obscure masses lying within adjacent tissue. Masses are more easily detected in a fatty breast.

Positioning.

A technologist performing mammography must include as much breast tissue as possible in the field of view for each image. The x-ray beam must pass through the breast tangentially to the thorax, and no other part of the body should intrude into the field of view, so as to not obscure any part of the breast. This requires both a cooperative patient and a skilled technologist. If a breast mass is located in a portion of the breast that is difficult to include in the image, mammography may fail to demonstrate the lesion. Also, because of these practical considerations, routine mammography is not performed in markedly debilitated patients.

The Nature of Breast Carcinoma.

Some breast carcinomas are seen as well-defined, rounded masses or as tiny, but bright, calcifications, and are easily detected. Others, however, may be poorly defined and irregular, mimicking normal breast tissue. Rarely, still others may have no radiographic signs at all.

For these reasons, it must be remembered that mammography has significant limitations in detection of carcinoma. It cannot be overemphasized that any suspicious finding on breast physical examination should be evaluated further, even if the mammogram shows no abnormality. Occasionally, additional imaging may reveal an abnormality, but if not, short-term close clinical follow-up or biopsy is warranted.

NORMAL STRUCTURES

Normal breast is composed mainly of parenchyma (lobules and ducts), connective tissue, and fat. Lobules are drained by ducts, which arborize within lobes. There are about 15 to 20 lobes in the breast. The lobar ducts converge on the nipple.

Parenchyma.

The lobules are glandular units and are seen as ill-defined, splotchy opacities of medium density. Their size varies from 1 to several millimeters, and larger opacities result from conglomerates of lobules with little interspersed fat. The breast lobes are intertwined and are therefore not discretely identifiable. This parenchymal tissue is contained between the premammary and retromammary fascia.

The amount and distribution of glandular tissue are highly variable. Younger women tend to have more glandular tissue than do older women. Glandular atrophy begins inferomedially, and residual glandular density persists longer in the upper outer breast quadrants. However, any pattern can be seen at any adult age (Fig. 5–3).

Along with glandular elements, the parenchyma consists of ductal tissue. Only major ducts are visualized mammographically, and these are seen in the subareolar region as thickened linear structures of medium density converging on the nipple.

Connective Tissue.

Trabecular structures, which are condensations of connective tissue, appear as thin (<1-mm) linear opacities of medium to high density. Cooper's ligaments are the supporting trabeculae over the breast that give the organ its characteristic shape, and are thus seen as curved lines around fat lobules along the skin– parenchyma interface within any one breast (Fig. 5–4).

Fat.

The breast is composed of a large amount of fat, which is lucent, or almost black, on mammograms. Fat is distributed in the subcutaneous layer, in among the parenchymal elements centrally, and in the retromammary layer anterior to the pectoral muscle (Fig. 5–4).

Lymph Nodes.

Lymph nodes are seen in the axillae and occasionally in the breast itself (Fig. 5–4).

Veins.

Veins are seen traversing the breast as uniform, linear opacities, about 1 to 5 mm in diameter (Fig. 5–4).

Arteries.

Arteries appear as slightly thinner, uniform, linear densities and are best seen when calcified, as in patients with atherosclerosis, diabetes, or renal disease.

Skin.

Skin lines are normally thin and are not easily seen without the aid of a bright light for film-screen mammograms. Various processing algorithms with digital mammography may allow better visualization of the skin.

SCREENING MAMMOGRAPHY

The standard mammogram (along with appropriate history-taking) makes up the entire screening mammogram. The indication for this examination is the search for occult carcinoma in an asymptomatic patient. Physical examination by the patient's physician, known as the clinical breast examination (CBE), and breast self-examination (BSE) are the other two indispensable elements in complete breast screening. Table 5–1 includes guidelines for frequency.

DIAGNOSTIC MAMMOGRAPHY

The diagnostic mammogram begins with the two-view standard mammogram. Additional maneuvers are then used as appropriate in each case, dictated by history, physical examination, and findings on initial mammography. Indications for diagnostic mammography are (1) a palpable mass or other symptom or sign (e.g., skin dimpling, nipple retraction, or nipple discharge that is clear or bloody) and (2) a radiographic abnormality on a screening mammogram. Additionally, patients with a personal history of breast cancer may be considered in the diagnostic category.

Other projections, magnification, and spot compression may be used to further evaluate abnormalities. These techniques provide better detail and disperse overlapping breast tissue so that lesions are less obscured.

Implant Views.

Patients with breast implants require specialized views to best image residual breast tissue because the implants obscure large areas of the breast tissue with routine mammography. These specialized views, Eklund or "push-back" views, displace the implants posteriorly while the breast tissue is pulled anteriorly as much as possible.

Ultrasonography

The indications for ultrasonography are (1) a mammographically detected mass, the nature of which is indeterminate; (2) a palpable mass that is not seen on mammography; (3) a palpable mass in a patient below the age recommended for routine mammography; and (4) guidance for intervention. Ultrasonography is a highly reliable technique for differentiating cystic from solid masses. If criteria for a simple cyst are met, the diagnosis is more than 99% accurate. Although certain features have been described as indicative of benign or malignant solid masses, this determination is more difficult to make and less accurate than the determination of the cystic nature of a mass.

A limitation of ultrasonography is that it is very operator dependent. Also, it images only a small part of the breast at any one moment. Therefore, an overall inclusive survey is not possible in one image, and lesions may easily be missed.

NORMAL STRUCTURES

The skin, premammary and retromammary fasciae, trabeculae, walls of ducts and vessels, and pectoral fasciae are well seen as linear structures. The glandular and fat lobules are oval, of varying sizes, and hypoechoic relative to the surrounding connective tissue (Fig. 5–5).

Simple cysts are anechoic (echo-free) and have thin, smooth walls. Increased echogenicity is seen deep to cysts (enhanced through-transmission). Most solid masses are hypoechoic relative to surrounding breast tissue.

Magnetic Resonance Imaging

Magnetic resonance (MR) imaging is used to evaluate the integrity of breast implants when the specialized mammographic views (Eklund views) are insufficient.

Other current applications include staging of tumor in the breast, search for a primary tumor in patients with cancerous axillary lymph nodes, evaluation of tumor response to neoadjuvant chemotherapy, and differentiation of dense breast tissue or fibrosis from tumor. Because of its present cost, inaccessibility, and lack of standardized interpretation guidelines, however, MR imaging of the breast is not yet widely used routinely.

Selection of pulse sequences and intravenous contrast administration is based on the indication.

The patient lies prone on the scanner table, and a specialized coil surrounds the breast. The patient must remain motionless in the scanner for several minutes at a time. The entire procedure time varies from 20 minutes to 1 hour. Intravenous contrast material is administered if carcinoma is to be ruled out.

NORMAL STRUCTURES

Tissues are differentiated by their pattern of change on different pulse sequences. The skin, nipple and areola, mammary fat, breast parenchyma, and connective tissue are normally seen, in addition to the anterior chest wall, including musculature, ribs, and their cartilaginous portions, and portions of internal organs. Small calcifications are not visible, and small solid nodules may not be detected. Cystic structures are well seen. Normal implants appear as cystic structures with well-defined walls. Their location is deep to the breast parenchyma or subpectoral, depending on the surgical technique that was used to place the implants. The internal signal varies and depends on implant contents, either silicone or saline.

Ductography

Ductography, or galactography, uses mammographic imaging with contrast injection into the breast ducts. The indication for use is a profuse, spontaneous, nonmilky nipple discharge from a single duct orifice. If these conditions are not present, the ductogram is likely to be of little help. The purpose is to reveal the location of the ductal system involved. The cause of the discharge is frequently not identified. Occasionally an intraluminal abnormality is seen, but findings have low specificity.

The patient lies in supine position while the discharging duct is cannulated with a blunt-tipped needle or catheter under visual inspection and with the aid of a magnifying glass. A small amount of contrast material (usually not more than 1 cm³) is injected gently by hand into the duct. Several mammographic images are then made. The procedure requires about 30 minutes and is not normally painful.

NORMAL STRUCTURES

Just deep to the opening of the duct on the nipple, the duct expands into the lactiferous sinus. After a few millimeters, the duct narrows again and then branches as it enters the lobe containing the glands drained by this ductal system. The normal caliber of the duct and its branches is highly variable, but normal duct walls should be smooth, without truncation or abrupt narrowing. With high-pressure injection, the lobules, as well as cystically dilated portions of ducts and lobules, may opacify.

Image-Guided Needle Aspiration and Biopsy

The indications for needle aspiration and biopsy of breast lesions are varied and are variably interpreted by radiologists and referring physicians. Two categories are discussed here.

The first indication is aspiration of cystic lesions to confirm diagnosis, to relieve pain, or both. Nonpalpable cysts require guidance with either ultrasound or mammography. A fine needle (20–25 gauge) usually suffices. The cystic fluid is not routinely sent for cytology unless it is bloody.

The second indication concerns solid lesions. Needle biopsy is used in this case to (1) confirm benignity of a lesion carrying a low suspicion of malignancy mammographically, (2) to confirm malignancy in a highly suspicious lesion prior to initiating further surgical planning and treatment, and (3) to evaluate any other relevant mammographic lesion for which either follow-up imaging or surgical excision is a less desirable option for further evaluation. Guidance for needle biopsy can be accomplished with stereotactic mammography, ultrasound, and MR. The imaging modality for needle guidance is selected on the basis of lesion characteristics, availability of technology, and personal preference of the radiologist. Ultrasound and mammography are most commonly used.

Large core needle biopsy (typically 14 or 11 gauge) has been shown to be more accurate for nonpalpable lesions than fine-needle aspiration (20 gauge or smaller), and is often combined with vacuum assistance to further increase tissue yield.

Mammographic guidance is most easily and accurately performed with a stereotactic table unit. Lesions of only a few millimeters can be successfully biopsied. With stereotactic tables, the patient lies prone with the breast protruding through an opening in the table surface. A needle is mechanically guided to the proper location in the breast with computer assistance (Fig. 5–6). The entire procedure requires 30 minutes to 1 hour.

Image-Guided Needle Localization

When a nonpalpable breast lesion must be excised, imaging is used to guide placement of a needle into the breast, with the needle tip traversing or flanking the lesion. Either ultrasonographic or mammographic guidance can be used, and the choice again depends on lesion characteristics and personal preference. Once the needle is in the appropriate position, a hook wire is inserted through the needle to anchor the device in place. This prevents migration during patient transport and surgery. After needle placement, the patient is taken to the operating area for excision of the lesion by the surgeon.

Biopsy Specimen Radiography

When a lesion is excised from the breast, a surgical specimen can be radiographed to document that the mammographic abnormality was removed. This practice is routinely followed with needle-localized lesions, but palpable lesions excised may also be radiographed to confirm that the specimen contains an abnormality that may have been present on the mammogram.

TECHNIQUE SELECTION

As with other organ systems, the task of the referring physician, with regard to breast imaging, is to determine which patients may benefit from these studies and which are the appropriate studies to order. To do this, the physician first categorizes the patient as asymptomatic or symptomatic:

1.Asymptomatic patients. As a group, these patients will benefit from routine screening mammography performed according to published national guidelines. A particular patient may require an individualized program for specific reasons. For example, a 30-year-old asymptomatic woman whose mother died of breast cancer at age 35 may justifiably begin yearly screening mammography.

2.Symptomatic patients. These are women who have any of the following signs or symptoms: a new or enlarging breast lump, skin changes (primarily dimpling), nipple retraction, eczematoid nipple changes, bloody or serous nipple discharge, and focal pain or tenderness. Diagnostic mammography is indicated in these patients. If the patient is under 35 years of age, the examinations may be differently tailored than for older patients. A telephone call to the radiologist may be helpful in determining a suitable evaluation plan in any patient for whom the usual guidelines are not helpful.

If a diagnostic study is needed, a standard two-view mammogram is obtained first. The need for further studies will be determined by the results of the mammogram. Whether ultrasonography or another modality is needed is best decided by the person interpreting the films, provided that he or she has the necessary clinical information available. For example, it is imperative that the location and description of a suspected mass be made known to the radiologist so that a specific search can be made for a lesion.

Also, knowledge of prior surgery, inflammation, or trauma to the breast is a requirement for accurate image interpretation. The different disease processes may have overlapping appearances on breast images, and refining the differential diagnosis, therefore, depends on accurate breast physical examination and the patient's history.

When it has been determined that an abnormality is present, then the decision as to whether close follow-up, needle biopsy, or excision is warranted is best made by integrating the image-based diagnosis and clinical considerations. Good communication between the radiologist and referring physician is needed to optimize management of breast lesions.

Patient Preparation

For the mammogram, two-piece clothing is most convenient because the patient will need to undress from the waist up. Patients should not apply antiperspirant to the breast or axilla, since it may cause artifacts.

Mammography is generally limited to ambulatory, cooperative patients because of the difficulties in proper positioning and because mammography units are not portable. If a debilitated patient has a palpable mass, then ultrasound would be a reasonable first step, followed by bedside needle aspiration or biopsy if the mass is solid. Screening mammography in markedly debilitated patients rarely has clinical utility.

Patients for whom stereotactic biopsy is being considered should be able to lie in the prone position without moving for about 1 hour.

Conflict with Other Procedures

Coordinating with other techniques is an infrequent problem with breast imaging. One situation that does occasionally cause difficulty occurs in the patient with a palpable mass that is aspirated with a needle prior to imaging. Aspiration of a simple cyst may cause bleeding into the lesion. Subsequent ultrasonography then shows a complex lesion with debris or some apparently solid elements, rather than a simple cyst. A complex lesion requires more aggressive management than does a simple cyst. Therefore, imaging is best performed prior to aspiration.

THE SYMPTOMATIC PATIENT: EXERCISE 5-1: THE PALPABLE MASS

(Please answer questions for this exercise before looking at the images that are presented with the discussion.)

Clinical Histories:

Case 5-1. A 34-year-old woman who noticed a new lump in her breast

Case 5-2. A 60-year-old woman who, on the insistence of her children, went for her first routine physical examination in many years. Her doctor found a mass in her breast.

Case 5-3. A 53-year-old woman who thinks she feels a hard nodule deep in her breast. Her breasts are of dense nodular texture. She had a normal screening mammogram 4 months ago.

Case 5-4. A 78-year-old woman with a soft, rounded mass discovered during physical examination

Questions:

Approach to the Palpable Lump

When a breast lump is found, several questions must be answered before proceeding with breast imaging. First, given that lumpy breasts are a normal variant, when is a lump significant? Experts in CBE advise palpation with the flat surface of two to three fingers, and not with the fingertips. With this technique, nonsignificant lumps will disperse into background breast density, but a significant lump will stand out as a dominant mass.

Second, is the lump new or enlarged? A new lump is more suspicious than a lump that has not changed over a few years.

Third, how big is the lump? Tiny pea-sized or smaller lumps, particularly in young women, are often observed closely with repeated CBE, because small breast nodules are extremely common, frequently resolve spontaneously, and are usually benign. Repeating CBE in 6 weeks allows for interval menses, which frequently causes waning or resolution of the lump. If the lump persists, diagnostic mammography is indicated.

Fourth, how old is the patient? If the patient is less than about 35 years of age, then radiation is avoided unless specifically indicated, because the younger breast is more sensitive to radiation. For patients older than 35 years, breast imaging begins with a diagnostic mammogram at the time a lump is deemed to be significant. The mammogram provides a view of the lump, as well as of the remainder of the involved breast and the opposite breast, where associated findings may aid in diagnosis and treatment planning.

If the patient is younger than 35 years of age, a significant lump is usually first examined with ultrasonography to determine whether a simple cyst is present. If there is no cyst, and the patient is younger than 30 years of age, a mammogram may then be obtained. The density of the breast in such a young patient may limit the usefulness of radiomammography, so the mammogram may be limited to one breast or to a single view.

For women between the ages of 30 and 40 years, judgment is needed as to whether other imaging is indicated. Several factors should be weighed, including age, family history of breast carcinoma, reproductive history, and findings at CBE. If the primary care physician is uncertain of the significance of the findings of a CBE, evaluation by a breast specialist may be helpful prior to requesting radiologic tests.

Discussion:

The 34-year-old woman in Case 5-1 indeed has a dominant mass, 2 cm in diameter on CBE. She says it was definitely not present until recently. She has no risk factors for breast cancer. The mass most likely is a fibroadenoma or a cyst, but carcinoma cannot be excluded. The patient now needs breast ultrasonography. (C is the correct answer to Question 5-1.)

Ultrasonography is best ordered before attempted needle aspiration because aspiration can alter the appearance of simple cysts, giving a misleading suspicious appearance. Therefore, answer E, needle aspiration, is incorrect.

Figure 5–7 shows an image from the ultrasound study, that represents the area precisely in the location of the palpable mass. This area is echo free, with sharply delineated walls and posterior acoustic enhancement (increased echogenicity deep to the anechoic area) consistent with a simple cyst. If these three features are seen, the probability of a simple cyst is greater than 99% and no further treatment is indicated unless the patient has pain and needs cyst drainage for symptomatic relief. Therefore, option B, excisional biopsy, is inappropriate because biopsy can be avoided by showing a simple cyst. No further imaging is needed. The patient is under the age of 40 years, not yet of screening age, and radiation should be avoided in young patients. Therefore, answers A and D, screening and diagnostic mammography, are not viable options until ultrasound is performed. Figure 5–8 illustrates the mammographic features of a cyst. The shape is round or oval, and the margins are smooth and sharply delineated.

Simple cysts are very common in the premenopausal patient and in patients who are being treated with replacement hormone therapy. A complex cyst is one that has internal debris—blood, pus, or tumor. A complex cyst requires further evaluation and a short-term follow-up (6–8 weeks) ultrasound may be sufficient. If the debris is due to attempted aspiration, it may clear on follow-up ultrasonography. Otherwise, excision or needle biopsy is indicated.

The 60-year-old woman in Case 5-2 has a 1.5-cm dominant mass on CBE. It is irregular and not freely mobile. The patient has never had a mammogram. Because she has a palpable mass, however, a screening mammogram is inappropriate, so option A is incorrect. Although the mass feels suspicious, she still needs a diagnostic mammogram prior to biopsy (option B, excisional biopsy, is incorrect) to exclude other lesions such as multifocal carcinoma. (D is the correct answer to Question 5-2.) The need for ultrasonography in a patient of this age is dictated by the mammographic appearance; therefore, option C, ultrasonography, is incorrect.

Her mammogram (Fig. 5–9) shows a very fatty breast, making any abnormal findings readily apparent. There is a mass measuring 1 cm in the upper outer quadrant that corresponds to the area of the palpated mass. The mass is of high density, being white on the mammogram. There is abundant spiculation and stranding around the mass, which is represented by the radiating linear densities around the periphery of the mass. There is also retraction of the linear patterns of the normal breast tissue; this retraction is known as architectural distortion. These findings represent the classical features of a malignant lesion on mammography, and this mass must be biopsied. A spiculated mass such as this is the most common appearance of invasive breast carcinoma. Less common signs are a circumscribed mass, asymmetric density, and architectural distortion alone. Intraductal (noninvasive) carcinoma more commonly appears as calcifications.

Spiculation around an invasive carcinoma corresponds to fingers of tumor, as well as to a desmoplastic reaction of adjacent normal breast tissue responding to the presence of tumor. This patient has an invasive ductal carcinoma. About 90% of primary breast carcinomas are ductal carcinomas, and the other 10% are lobular carcinomas.

Besides carcinoma, the primary differential diagnosis for a spiculated mass includes postsurgical change, other trauma with hematoma, fat necrosis, infection, and radial scar (a complex, spontaneous benign lesion involving ductal proliferation, elastosis, and fibrosis).

There are no other lesions in this patient's breast, and the other breast appears normal. By mammographic criteria, then, the patient is a good candidate for treatment with lumpectomy and radiation therapy rather than mastectomy. Her tumor is solitary localized to one quadrant and her breast tissue is otherwise easy to evaluate mammographically. Recurrent tumor or additional lesions should, therefore, be readily seen on post-treatment follow-up mammograms.

For a mass that feels malignant and appears suspicious on a mammogram, fine-needle aspiration (FNA) at the bedside may provide a rapid cytological diagnosis of carcinoma. Because FNA best follows mammography, option E, needle aspiration, is incorrect. FNA may then be followed by definitive surgical treatment at a later date, after the patient has had time to consider the treatment options available. If FNA fails to disclose carcinoma, then excisional biopsy is required because of the suspicious findings on mammography and CBE. The occasional false-negative FNA occurs with tumors that do not shed cellular material readily.

Cytology of this palpable mass revealed ductal carcinoma and this patient chose to have a lumpectomy.

The 53-year-old patient in Case 5-3 has an ill-defined 1.5-cm hardened nodular area in her breast. Results of screening mammography less than 1 year ago were normal. Her breast tissue is not fatty, as in Case 5-2, but she has quite dense, nodular, fibroglandular tissue, which may obscure small masses. The average doubling time of breast carcinoma makes it unlikely that she has a palpable carcinoma that is entirely new since her last mammogram. It is quite possible, however, that she has had a smaller cancer for a few years and that it has now grown large enough to be palpated. Breast tumors are typically not palpable unless they are at least 1 cm in diameter. Before this stage, in the preclinical phase, the tumor may be visible up to 2 to 3 years earlier on the mammogram if the breast is fatty. In dense breasts, as discussed previously, tumors may not be seen on the mammogram until later stages. For this reason, regular BSE and CBE are important. Mammography will miss some cancers, regardless of the situation, at a rate variably reported to be between 5% and 15%.

With a new area of abnormality on physical examination, being in a high-risk age group (more than 50 years old), and having a dense parenchymal pattern, the patient needs another mammogram, this time a diagnostic mammogram of the involved breast only. (D is the correct answer to Question 5-3.) Option A, screening mammogram, is incorrect, because it is too soon to repeat screening mammography at this time and the patient does have a palpable finding—as contraindication for a screening study.

Figure 5–10A shows a vague, rounded opacity within dense fibroglandular tissue. This is in the area of the palpable mass, as indicated by a small metallic marker (much like a BB pellet) taped on the skin over the abnormality. Detail is not adequate to make a judgment as to the possibility of malignancy here, or even to confirm that a real lesion is present. The appearance may merely be due to superimposed normal breast shadows. Compression spot films are needed to confirm the presence of a mass and to better define its borders.

Figure 5–10B shows spot compression of the questioned opacity seen on initial images. This localized compression with a smaller paddle placed directly over the abnormality achieves two things. First, it separates the opacity from adjacent breast tissue, demonstrating this to be a discrete mass with high density and not merely a superimposition of normal shadows. Second, it elicits clear spiculation and architectural distortion around the mass. These features are classic for breast carcinoma, and biopsy is therefore required. Biopsy of this lesion showed invasive ductal carcinoma.

The 78-year-old patient in Case 5-4 has a soft mass in her breast and clearly needs a diagnostic mammogram because of her age and the palpable findings. Soft, rounded masses on physical examination are often benign fibroadenomata or cysts, but carcinoma may also present this way. (Statement B is false.)

Other benign causes of these physical findings include hematoma, abscess, and lipoma. (Statement E is true and the correct answer to Question 5-4.) Therefore, a mammogram may be beneficial for two reasons: (1) If a benign finding is revealed, biopsy may be avoided; and (2) if findings suggest malignancy, optimal treatment can be planned on the basis of the extent of the lesion and the presence or absence of additional lesions. (Statement A is false.)

Her mammogram (Fig. 5–11) shows two findings. There is a rounded mass with multiple lobulations and circumscribed borders. The fact that the borders are not sharply outlined on all sides raises the suspicion level for this finding. Masses that are sharply delineated may be followed with serial mammograms at 6-month intervals if they are known not to be new, are nonpalpable, and show no other features of malignancy. This is not the case with the patient in Case 5-4. Note the fading margin along portions of the mass. This mass corresponds to the palpable finding. Ultrasonography would be useful to exclude a multiloculated cyst and show the lesion to be solid. Biopsy is indicated, but needle aspiration without imaging would have been inappropriate. (Statement C is false.)

A circumscribed mass representing carcinoma is seen less often than a spiculated mass. About 10% of invasive ductal carcinomas represent the better differentiated subtypes, including medullary carcinoma, mucinous (colloid) carcinoma, and papillary carcinoma, all of which are frequently seen as circumscribed masses. They tend to have a better prognosis than the less well-differentiated garden-variety ductal carcinomas.

The differential diagnosis for the circumscribed mass on mammography includes carcinoma (primary as well as metastatic), fibroadenoma, and cysts; hematoma, abscess, and miscellaneous benign lesions are seen much less often. Correlation with clinical history and physical examination can help to narrow the differential diagnosis. When carcinoma cannot be excluded, either needle aspiration or excisional biopsy is required.

This patient had a needle biopsy. Because palpation alone could not reliably localize this lesion for needle biopsy because of its soft nature and the difficulty in fixing its position, stereotactic mammographic guidance was used in localizing the lesion for this procedure. The diagnosis of mucinous carcinoma was made by microscopic inspection of the specimen.

Now, were you astute enough to perceive the second lesion? Above and to the left of large mass is a smaller, dense spiculated mass. This was also biopsied and proved to be a carcinoma of the very well-differentiated tubular type. Even though the patient has two lesions now, both carry an excellent prognosis and she will be unlikely to die from breast carcinoma. (Statement D is false.) In fact, although mastectomy is certainly a reasonable treatment for her, local excision would also be an option with these nonaggressive lesions.

THE SYMPTOMATIC PATIENT: EXERCISE 5-2: LUMPINESS, NIPPLE DISCHARGE, AND PAIN

Clinical Histories:

Case 5-5. An 82-year-old woman who complains of newly lumpy, painful breasts. Figure 5–12 is the same breast; part A was taken 1 year before B.

Case 5-6. A 45-year-old woman with a serous nipple discharge. Ductography was performed (Fig. 5–13).

Case 5-7. A 37-year-old woman who comes to the emergency department with a reddened, swollen, painful left breast. The right (A) and left (B) breast are shown in Fig. 5–14.

Case 5-8. A 52-year-old woman with soreness in the right breast, the mammogram of which is seen in Fig. 5–15.

Questions:

Radiologic Findings:

5-5. The mammograms of Fig. 5–12 show a diffuse marked increase in mammographic density with a nodular character.

5-6. In the ductogram of Fig. 5–13, contrast has been injected into a portion of a single ductal system with opacification of the lactiferous sinus and larger branching ducts. Most of the walls are smooth, as they should be. However, there is a filling defect in one of the major branches, as exhibited by the lucency outlined by contrast on all sides and indicated by the arrow. (Statement C is false.)

5-7. Mammograms of the right and left breast (Fig. 5–14) show that the entire left breast (B) is abnormally dense.

5-8. Mammogram (Fig. 5–15) shows a large band of high density with markedly spiculated margins in the upper part of the breast.

Discussion:

Lumpy breasts are a variant of normal and, as such, require careful physical examination and mammography to detect any carcinoma and to avoid unnecessary surgery. Diffuse lumpiness is not a contraindication to screening mammography, but when a particular lump becomes dominant, a diagnostic study is indicated.

The two mammograms of the patient in Fig. 5–12 were obtained 1 year apart. Between these two exams, the patient began to exhibit menopause symptoms and was started on hormonal replacement therapy. (A is the correct answer to Question 5-5.) The breasts, which were previously largely fatty (A), have become moderately dense and very lumpy on palpation 1 year later (B). This change can also be seen, although not usually as dramatically, in the perimenopausal time of estrogen flare.

Such changes can be seen asymmetrically or unilaterally, and it is useful to remember the estrogen effect when evaluating mammograms with interval changes. Correlation with clinical history is then needed.

Answer B, infectious mastitis, and answer C, carcinoma, are incorrect because both of these entities are usually unilateral and focal. Option D, congestive heart failure (CHF), is incorrect because CHF causes bilateral changes that have a more linear pattern of trabecular thickening on mammography, rather than the patchy, ill-defined nodular pattern characteristic of glandular and cystic densities seen here. Answer E, cystic disease, is incorrect. Cysts are seen as a component of hormone-related breast changes, but spontaneous cystic disease alone is rare at this age.

In the patient in Case 5-6, a single intraluminal filling defect is seen on ductography (Fig. 5–13). However, we cannot determine from these findings alone whether the defect is due to a benign or a malignant nodule (statement D is false), although approximately 90% of nipple discharges are due to benign causes (statement B is false). The filling defect in this woman was a benign papilloma, the most common cause of bloody or serous discharge. Mammograms usually do not show these small, intraductal nodules.

Whether or not a filling defect is seen on a ductogram, biopsy is needed to rule out carcinoma, and the ductogram may be helpful in showing the surgeon which area of the breast harbors the cause of discharge. (Statement E is true.) However, many surgeons are able to identify the lobe(s) involved by the pathology by inspecting the nipple, noting the location of the discharging duct, and by palpation, observing which portion of the breast produces discharge when compressed. In normal patients, ductography is not easily performed and is of limited usefulness when discharge is not spontaneous, profuse, and confined to a single duct. Therefore, statement A is false; ductograms should not be performed on all patients with nipple discharge. Furthermore, only bloody or serous discharges are of concern. A large portion of patients with discharge have secretions typical of fibrocystic change (i.e., a dark brownish or greenish fluid rather than a truly bloody or serous discharge). Milky discharge is normal.

In Case 5-7 (Fig. 5–14), the patient's entire left breast is abnormally dense. (Statement A is true.) There is skin thickening as well. This is a nonspecific appearance (statement D is true); infection and inflammatory carcinoma are both high on the differential diagnosis list. (Statement B is true; C is false and therefore the correct answer.) Breast carcinoma may incite an inflammatory response in the breast, mimicking a benign infectious process both clinically and radiographically. The patient turns out to have an elevated white blood cell count and fever with marked pain. This information now makes infection more likely than tumor, and a course of antibiotics with follow-up imaging to monitor resolution is appropriate. (Statement E is true.)

Figure 5–16 shows the follow-up mammogram after significant clinical resolution. The mammographic findings have resolved, and the left breast now appears very similar to the right one.

Infectious mastitis occurs more frequently in lactating women but is not uncommon in nonlactating women, particularly in diabetic patients. Imaging (mammography or ultrasound) is useful to exclude a drainable abscess collection and to provide a baseline for monitoring resolution to exclude carcinoma.

Case 5-8 illustrates the importance of correlation with history and physical examination. This patient has pain, as in the last case, but her mammographic abnormality (Fig. 5–15) is much more localized and appears more like a malignant mass, being a high-density opacity with excessive spiculation. However, this, too, is a benign process. The patient was in a motor vehicle accident 2 months earlier and sustained a severe injury to the right side of her chest. Physical examination shows a resolving laceration and contusion that extends in a linear fashion over the right breast. (No wonder she is sore!) A CT scan performed at the time of trauma showed the acute injury precisely in the area shown on the mammogram. These mammographic features are consistent with resolving (or acute) trauma. Therefore, no further action is warranted at this time, other than follow-up. (Statement C is true and is the correct answer to Question 5-8.) Although pain is not a prominent feature of carcinoma, patients with cancer may be symptomatic. Therefore, pain does not always mean benignancy. (Statement A is false.)

The mammographic appearance would certainly be highly suspicious for invasive carcinoma in the absence of clinical information, but with careful correlation we are able to avoid biopsy in this case. (Statement B is false.)

Anticoagulation therapy with resultant bleeding could also have this appearance. (Statement D is false.)

Fibrocystic change, although very common, is an unlikely diagnosis. Fibrocystic change appears as increased cloudy densities, nodular densities, and occasionally some thickened linear densities, but rarely as a spiculated mass. (Statement E is false.)

THE ASYMPTOMATIC PATIENT: EXERCISE 5-3: THE FIRST MAMMOGRAM

Clinical Histories:

Case 5-9. A 40-year-old woman whose mother died of breast carcinoma (Fig. 5–17)

Case 5-10. A 42-year-old woman with no risk factors for breast carcinoma. She has no symptoms (Fig. 5–18)

Case 5-11. A 45-year-old woman, asymptomatic, with no risk factors (Fig. 5–19)

Questions:

Radiologic Findings:

5-9. Detail of mammogram (Fig. 5–17) of the patient in this case shows a smoothly marginated small mass with a lucent center (arrow).

5-10. The mammogram in this case (Fig. 5–18) shows a circumscribed mass (arrows) with internal lucency as well as opacity.

5-11. The mammogram of the patient in Case 5-11 (Fig. 5–19) shows a nodular density (arrow), with indistinct margins.

Discussion:

In Case 5-9 (Fig. 5–17), the 40-year-old woman has a strong family history of breast cancer, which puts her at high risk for developing the disease. As stated in the introduction to this chapter, great controversy exists concerning when mammographic screening should be initiated and the appropriate frequency of examinations in different groups. Most experts agree, however, that patients with a strong family history will benefit from screening beginning at age 40. The American Cancer Society (ACS) recommends annual screening above age 40 in all female patients; therefore, B is not the correct answer.

Although the upper age limit for mammographic screening has not been defined, we certainly cannot recommend cessation over age 65, since the prevalence of breast cancer is greatest in women in their fifties and sixties. (C is the correct answer to Question 5-9.) Current ACS guidelines recommend yearly mammograms for all women older than 40 years. Appropriate age for termination of screening is best judged by the patient's physician, weighing life expectancy against potential benefits from screening.

ACS also recommends yearly physical examination by the physician and monthly BSE by the patient to detect tumors missed by mammography, as well as those that become detectable between routine mammograms (interval cancers). Therefore, A and D are not correct answers to Question 5-9.

The mammogram for the patient in Case 5-9 (Fig. 5–17) is normal and demonstrates a typical normal lymph node. The node is smoothly marginated and has a fatty hilum, indicated by the darker center.

In Case 5-10, there is a circumscribed mass in the axillary tail of this breast (Fig. 5–18). The key to diagnosis is the mixture of densities within the lesion. Medium-density opacities are interspersed with lucencies within a smoothly marginated mass. This appearance is pathognomonic for a fibroadenolipoma, sometimes called by the misnomerhamartoma. (B is the correct answer to Question 5-10.) Being composed of elements of normal breast (fatty, glandular, and fibrous tissues) organized within a thin capsule, a fibroadenolipoma forms a "breast within a breast." As such, it is benign and needs no further evaluation. It may be palpable as a soft mass.

The point to remember here is that fat-containing masses are always benign. Answer D, ductal carcinoma, is incorrect. The differential diagnosis of a fatty mass, besides fibroadenolipoma, includes lymph node, as in Case 5-9, galactocele, lipoma, and oil cyst. Galactoceles are usually smaller and are seen in lactating women. (Answer C is incorrect.)

Oil cysts result from fat necrosis and are usually smaller. Typically, they are entirely lucent, because they are filled with oil, except for a thin wall. (Answer E is incorrect.)

Option A, complex cyst, is incorrect because this entity would not contain fat. A cyst, whether it contains serous fluid, blood, or pus, is always opaque and of low to high density, not lucent.

In Case 5-11, an asymptomatic 45-year-old woman's first mammogram (Fig. 5–19) shows a 1-cm nodule centrally located in this breast. The differential diagnosis remains broad without further studies to help characterize this nodule. All choices except option C, intraductal comedocarcinoma, may have this appearance. Intraductal carcinoma, when not mammographically occult, usually appears as microcalcifications. Because the margins are indistinct, however, the patient must be recalled for additional imaging to rule out carcinoma.

The sonographic image shows a solid lesion, ruling out a simple cyst. Spot compression is then used to evaluate the borders. If all margins were to appear smooth, one acceptable course of action would be serial 6-month follow-up mammograms for a period of 2 years to demonstrate stability. If any change occurs during this time, biopsy is indicated.

Spot compression (Fig. 5–20A ) reveals that portions of the border are not smooth, raising the level of suspicion for malignancy. To exclude carcinoma, biopsy is needed.

Biopsy may be accomplished with excision or with needle biopsy. Excision would require needle localization of the nodule for the surgeon, since this is a nonpalpable lesion. Core needle biopsy, either stereotactic or ultrasound guided, is preferable because it is minimally invasive, causes less morbidity to the patient, leaves no distortion in the breast or on the skin, and is often less expensive than surgical excision. Accurate needle biopsy devices, however, are expensive and are not universally available.

This nodule was diagnosed as a fibroadenoma with stereotactic core needle biopsy (Fig. 5–20B ). Fibroadenomas are very common and are frequently the cause of benign breast biopsy. They occur in very young women (teenagers and women under 30 years of age) and persist undiscovered, through the age at which the first mammogram is obtained, then on discovery, become a concern of both physician and patient. They may also become palpable or mammographically visible in older women after previously normal mammograms. They continue to be a management problem, because fibroadenoma and carcinoma have overlapping mammographic features and both are common lesions in middle-aged women. With age, fibroadenomas become involuted and heavily calcified, thereby revealing their true identity (Fig. 5–21). Without this appearance, however, biopsy is often necessary.

A high index of suspicion and careful evaluation, together with either close follow-up or liberal use of needle biopsy, are needed to minimize both false-negative impressions and excessive breast surgery.

THE ASYMPTOMATIC PATIENT: EXERCISE 5-4: ARCHITECTURAL DISTORTION AND ASYMMETRIC DENSITY

Clinical Histories:

Case 5-12. A 51-year-old woman evaluated with screening mammography (Fig. 5–22)

Case 5-13. A 61-year-old woman evaluated with screening mammography (Fig. 5–23)

Questions:

Radiologic Findings:

5-12. Bilateral craniocaudal views (Fig. 5–22A ) show architecture distortion in the right breast without a discrete dominant mass.

5-13. Bilateral mediolateral oblique views of the patient in this case (Fig. 5–23) show areas of asymmetric density in the left upper and right lower breast. The densities are interspersed with fat. Margins are generally concave and there is no architectural distortion.

Discussion:

Although normal breast tissue is remarkably symmetric, it is never exactly the same on both sides. The challenge in mammography is to recognize normal variation and to be able to distinguish nonpathologic asymmetry from disease. This is not always possible, particularly in the asymptomatic group. A high index of suspicion is needed when evaluating the screening mammogram, just as in the baseline CBE. Once asymmetry is noted mammographically, a careful, focused breast examination is needed. If no suspicious areas are detected and if the radiographic features suggest fibroglandular tissue, then follow-up alone is adequate. Radiographically, we look for a homogeneous, nondistorted pattern of fat interspersed with lobular densities. Any dominant mass or architectural distortion should cause concern.

In Case 5-12 (Fig. 5–22A ), one area shows a different architectural pattern. The lines of tension appear to pull to a central focus. This is a classic appearance of invasive lobular carcinoma. Remember that 90% of the breast cancers are ductal in origin, and the other 10% are lobular, as in this case. This type of carcinoma shows a subtle infiltrating pattern much more often than does ductal carcinoma. (Statement D is true.)

One of the problems with this disease is that it is difficult to describe the extent of tumor mammographically. There is a large area of asymmetric architecture in this patient, but where tumor ends is unclear. This patient had a carcinoma that measured 4 cm.

A correlated clinical examination often reveals abnormalities not detected without the guidance of mammographic findings. (Statement C is false and is the correct answer to Question 5-12.) Biopsy of any suspicious-feeling area is strongly recommended. Studies have shown that a high percentage of carcinomas "missed" at mammography appear as architecture distortion or asymmetric density. This patient did have a large area of thickening in the upper aspect of this breast, confirming the suspicious nature of the mammographic findings.

Previous mammograms are definitely useful in evaluating architecture distortion and asymmetric density. If the finding is unchanged over time, no further action may be needed. If the finding is new or is increasing, it is more easy to recognize. (Statement B is true.) Hormonal therapy may indeed have an asymmetric effect (statement E is true), but it does not take the form of architecture distortion.

Surgical biopsy may result in such distortion of the architecture, but precise correlation with location and timing of the surgery is needed. (Statement A is true.)

Unlike the previous patient, the woman in Case 5-13 has multiple areas of breast asymmetric density (Fig. 5–23). There is a large area in the upper part of the left breast and a smaller area in the lower part of the right breast. Both areas show fat interspersed with fibroglandular densities. There is no architectural distortion. Margins of the larger opacities are generally concave—a sign of benignity. There are no dominant or circumscribed masses, and cystic disease therefore would not be part of the differential diagnosis, because cysts are rounded masses. (D is the correct answer to Question 5-13.) Having learned from the previous case that missed carcinoma often presents as asymmetric density, tumor must remain in the differential diagnosis, and answer E is incorrect.

Both trauma and postoperative change can lead to ill-defined asymmetric density. With trauma there may be bleeding, contusion, or actual deformity, if severe. With surgery, asymmetry results both from removal of normal tissues, leaving less density on the operated side, and from surgical trauma (hematoma and distortion) that causes increased localized densities. Therefore, options B and C are both incorrect. The most likely cause of this woman's mammographic appearance is normal breast tissue, and answer A is incorrect. The multiplicity and bilaterality of areas of asymmetry, the lack of signs or symptoms of breast cancer, and the fibroglandular characteristics of the densities all support this diagnosis.

THE ASYMPTOMATIC PATIENT: EXERCISE 5-5: THE FOLLOW-UP MAMMOGRAM

Clinical Histories:

Case 5-14. A 70-year-old woman who had two screening mammograms 1 year apart Figure 5–24A is the first mammogram and Part B is the one obtained a year later.

Case 5-15. A 66-year-old woman with this screening mammogram after a previously normal mammogram (Fig. 5–25)

Case 5-16. A 55-year-old woman who had a normal mammogram the previous year (Fig. 5–26)

Questions:

Radiologic Findings:

5-14. Figure 5–24 shows back-to-back craniocaudal views of the right breast obtained 1 year apart. In the interval a small spiculated mass has enlarged so as to become more apparent (arrow).

5-15. The mammogram of the patient in this case (Fig. 5–25) shows a cluster of microcalcifications posteriorly in the central aspect of the breast. Previous mammograms have been normal.

5-16. Magnification view of a portion of the breast of the patient in this case (Fig. 5–26) shows coarse calcifications, some of which are rounded or ring-like.

Discussion:

Case 5-14 (Fig. 5–24) illustrates the concept of developing density. A developing density is any opacity that increases in size or density over time. All such opacities should be evaluated critically, because they can be signs of carcinoma. This concept is based on the natural behavior of breast cancer, which generally grows slowly. With periodic screening, the early tumor will be imaged but unrecognized on early images and may not be detected until 1, 2, 3, or more years later. Tumors 5 mm or smaller are very difficult to differentiate from normal breast tissue, but masses larger than 1 cm are more easily detected. The typical breast cancer has been present for several years by the time it is 1 cm in size. Therefore, breast cancers are routinely visible in retrospect on previous mammograms if the patient has had frequent screening. This does not mean, however, that malpractice has occurred. If the cancer is still small, no harm has been done and more harm could potentially be done by biopsying all such tiny densities, because most of them would be normal breast. (Statement C is true.) Being suspicious but judicious with any developing density, therefore, is necessary to detect breast cancer early without unnecessary biopsy.

This patient has a small (about 1-cm) spiculated mass in the central part of the breast. (Statement A is true.) It has increased slightly in size over 1 year, with a growth rate typical for breast carcinoma. (Statement B is false and is the correct answer to Question 5-14.) Being so small in a medium-sized breast, it is unlikely to be palpable (statement Dis true) and, therefore, would require imaging guidance for any biopsy. The spiculated margins, the rate of growth, and the patient's age group all make this a very suspicious lesion, and biopsy is warranted. (Statement E is true.) This lesion was an infiltrating ductal carcinoma.

Case 5-15 illustrates a new finding after a previous normal screening. Figure 5–25 shows a cluster of microcalcifications in the central area. Note that the calcifications are small and irregular, but we do not see their configuration exquisitely; nor can we be confident of the extent of disease, since there may be other smaller calcifications that we do not see. The patient, therefore, requires recall for magnification mammography (Fig. 5–27). (Statement E is true.) On magnification, we can appreciate that the calcifications are of many different sizes and shapes (i.e., pleomorphic). (Statement A is true.) Malignant microcalcifications are usually less than 0.5 mm in size, and the very coarse calcifications are classically benign. However, there is significant overlap, and configuration is generally a more helpful sign. Malignant calcifications are usually either granular or linear and branching.

These granular, linear, and branching calcifications are typical of intraductal carcinoma. The aggressive type of intraductal carcinoma, comedo or high-nuclear-grade carcinoma, causes necrosis in the cancerous mammary duct walls. Calcifications form in areas of necrosis forming a "cast" of the duct. This process results in the linear and branching forms of calcification. (Statements C and D are true.) Pathologic analysis of this tissue showed intraductal carcinoma of the comedo type.

Lesser degrees of necrosis result in smaller, more granular calcifications, whereas extensive necrosis yields rather large rod-shaped or branched calcifications. Statement B is false because, although large calcifications alone are usually benign, the mixture of tiny irregular calcifications with the coarse casting calcifications remains very suspicious for malignancy. (Statement B is false and is the correct answer to Question 5-15.)

In Case 5-16 the mammogram detail (Fig. 5–26) shows typical benign calcifications. Benign calcifications take many forms, but if we see rings with lucent centers, as in this case, we can rest assured that they are benign. These rings are calcifying microcystic areas of fat necrosis. This is a very common benign finding. Punctate, or dot-like, calcifications are also usually benign if uniform and smooth. Granular calcifications are more angular, like broken needle tips, and would be more suspicious. (Statement A is false.)

Benign calcifying processes such as fibroadenoma, sclerosing adenosis, and fat necrosis can all be unifocal, or regional, as well as multifocal or diffuse; therefore, distribution alone does not make calcifications suspicious. (Statement B is false.)

Benign processes of many types do present in adulthood and, therefore, may appear de novo after a previously normal screening examination. Again, the configuration of calcifications is more helpful. (Statement D is false.)

For obviously benign calcifications such as these, routine follow-up alone is adequate. (Statement C is false.) Some calcifications are obviously malignant as in Case 5-15. A third group of calcifications is classified as indeterminate, and these require further evaluation, either close mammographic follow-up or some type of biopsy. Taken as a group, biopsied microcalcifications historically have had a rate of malignancy of only 20%. Therefore, statement E is true, since these ringlike calcifications have a better-than-average chance of being benign. (Statement E is true and is the correct answer to Question 5-16.)

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