Breast imaging

Mammography

 

Indications

Mammography remains the gold standard among the imaging modalities of the breast due to its overall accuracy, relative simplicity and low cost. Every woman from the age of 30 with a significant breast problem should have a mammogram. Mammography should be performed even in the presence of a physical finding that appears benign. A tumor which feels smooth and mobile may represent a carcinoma. Furthermore, a non-specific thickening may be the only physical finding in a patient with carcinoma. Women between 25 and 30 should have a mammogram only if there is a clear clinical suspicion of malignancy. In our opinion, women below the age of 25 should only exceptionally be referred for mammography due to the extremely low risk of carcinoma and the, albeit somewhat hypothetical, risk of radiogenic carcinoma. FNAB is often sufficient in the young woman.

Mammography should be undertaken even in the presence of a clear clinical diagnosis of breast carcinoma. A mammogram will help to clarify the exact position of the tumor, the extension of tumor outside the palpable mass and the presence of multiple foci of carcinoma (Fig. 9) as well as the status of the contralateral breast. This information is critical for proper planning of the treatment.

Figure 10. 74-year old woman with a pacemaker. The breast tissue is well visualized.

There are no absolute contraindications to mammography. Patients with a pacemaker can be examined, provided due caution is observed when compression is applied to the breast (Fig. 10). Also patients with silicone and other types of prostheses can be examined without problems (see below).

Pregnant women can undergo mammography. The scattered radiation of mammography is of low energy and will be absorbed in the skin. Thus, the fetus will not be exposed to any radiation. For psychological reasons it is wise to put a lead apron on the patient, also it is very important to give proper information to the patient before the examination, so that the patient can make the final decision herself. During the last two months of pregnancy and even more so during lactation, the breasts are usually very dense, resulting in a relatively low sensitivity for carcinoma.

Examination technique

Proper examination technique in mammography is of critical importance. Positioning and compression are vital components of the

a

Figure11. a) Patient positioned for the oblique view.The tube should be angled between 45 and 60 degrees depending on the habitus of the patient. b) Oblique view of the left breast. The pectoral muscle should be visible down to the midplane of the breast. Ideal/y, the muscle should have a convex border, indicating that the patient has relaxed the muscle which is important for proper positioning. The inframammary fold and abdominal skin should be included.

b

technique (Fig. Il). Not only the technologist but also the radiologist should have a thorough knowledge of the principles of the examination technique. Continuous critical evaluation of the mammograms regarding adequacy of positioning and compression is necessary to maintain a high quality. Faulty positioning may result in a missed diagnosis of carcinoma.

For the positioning it is important to be aware of the anatomy of the breast and especially the different mobility of various parts of the breast. Basically, the lateral and lower portions of the breast are mobile, while the superior and medial portions are relatively more fixed. Also, the cassette holder of the mammography unit is fixed while the compression plate is mobile. These circumstances should be taken advantage of when performing the mammography. Thus, the mobile part of the breast should be moved by the technologist's hands towards the cassette holder in order to minimize the amount of tissue that is exc1uded, when the compression is applied.

Even with good technique it is not possible to inc1ude all breast tissue on any single view (Fig. 12). On the oblique view the medial juxtathoracic

a

Figure 12. Asymptomatic 57-year old woman undergoing screening examination. a) Craniocaudal b) oblique view. On both views two calcifications are seen (arrow). The distance from the calcifications to the posterior edge of the film is 2 cm in the craniocaudal view, while in the oblique view the corresponding distance is 7 cm, illustrating that the superior, juxtathoracic portion of the breast is not imaged in the craniocaudal view.

b

Portion of the breast tends not to be included. Similarly, on the straight lateral view the most lateral juxtathoracic portion tends to be missed. On the craniocaudal view the most superior portion of the breast tends not to be imaged. Also, on the craniocaudal view either a lateral or a medial juxtathoracic portion is omitted depending on how the patient is rotated.

For examination of the symptomatic patient, either two (craniocaudal and oblique) or three (craniocaudal, oblique and lateral) views should be obtained (Fig. 13). For screening purposes either one (the oblique) or two (craniocaudal and oblique) views should be obtained. Most centres

Figure 13. The standard projections of mammography. The most common extension of the glandular tissue is indicated. The arrows show the beam direction: 1. oblique, 2. craniocaudal, 3. lateral projection.

today use two views, at least as a base line examination. After a base line two-view study we obtain two views on dense breasts in subsequent examinations, while in predominantly fatty breasts only one view, the oblique, is obtained.

Patients with silicone prosthesis should have the regular views and in addition so called Eklund views. This means that the tissue anterior to the prosthesis is compressed separately while displacing the prosthesis towards the chest wall.

It cannot be emphasized enough that the examination of the symptomatic patient has to be tailored to the individual patient. Additional views, such as coned down views with localized compression to spread the structures apart, and magnification views should be obtained as necessary, often in combination. Slightly angled views (plus and minus 5 to 10 degrees) are often useful in the investigation of a small unclear dens it y seen in one projection only. If caused by superimposition, the slightly angled views will usually "resolve" the density. Once the presence of a lesion has been confirmed, further characterization can often be accomplished by using either magnification or coned down views or a combination of both. Good viewing conditions for mammography include proper light boxes, access to a bright light, a magnifying lens or a special viewer.

Correlation with clinical findings is often useful and indeed necessary, if there is any discrepancy between the radiologic findings and the physical findings cited by the referring physician. A small lead marker on the skin overlying the physical finding is often useful. Even with good mammographic technique, 5 to 10 per cent of carcinomas with positive

Figure 14. Asymptomatic 33-year old woman with a family history of breast cancer. Very dense breast parenchyma. Compare the predominantly fatty breast in figure 11 b. The radiographic demonstration of a tumor is more difficult in a dense than in a fatty breast.

physical findings (albeit not always characteristic for carcinoma) cannot be demonstrated on mammography. This may be due to dense breast parenchyma, the growth pattern of the tumor or a combination of these factors. Thus, a suspicious physical finding with a negative mammogram needs further investigation.

Anatomic considerations

The radiographic appearance of the female breast shows greater variations than that of any other organ of the body. This is due to a considerable variation in the proportion of fibroglandular, dense tissue in relation to fat tissue, which is relatively radiolucent (Fig. 14). This variation is related to several factors, age being one of the most important. Generally speaking, premenopausal women have more fibroglandular tissue than postmenopausal women. During pregnancy and lactation there is a substantial increase in the density of the breast due to proliferation of the glandular tissue. Hormone replacement therapy in the menopause may also increase the density of the breast (Fig. 15). The change is usually generalized, but may be focal.

a	b
Figure 15. 58-year old, asymptomatic woman. a) Oblique view of the right breast. b) Same view two years later. The dense tissue component has increased substantially in b). The findings were identical in the left breast. The patient was put on hormone replacement therapy six months prior to the examination in b).

Other factors related to the density of the breast are age at first pregnancy and a history of breast cancer. Women with an early first pregnancy tend to have more fatty breasts than women with a late first pregnancy or no pregnancy at all. Women with a history of breast cancer tend to have denser breasts than women without a cancer history. The density of the breast may also be related to other risk factors for breast cancer. It is also the single most important factor in determining the sensitivity of mammography. Thus, on average, mammography is somewhat less sensitive in younger than in older women, and also in high-risk women compared to low-risk women. It is important to realize that these are statistical relationships only. In practice, there are many exceptions. Thus, many younger women have predominantly fatty breasts, and older

Figure 16. 48-year old woman with tender, nodular breasts. On the mammogram multiple tumors of varying size are seen. The tumors seem to be well circumscribed although the margin cannot be followed all around in most of the lesions, presumably due to superimposition. The patient had had repeated aspirations of benign cysts. Radiographic diagnosis: Fibrocystic changes.

women may have dense breasts. The radiologist's report should include a statement of the density of the breast parenchyma to give the referring physician an idea of the sensitivity of the procedure.

Another important reason for the extensive normal variation of the anatomy of the breast is the common occurrence of fibrocystic changes. This is a not well-defined proliferative process in the breast parenchyma with a diffuse borderline between the normal and pathological. From a radiographic point of view the result is increased density of the breast parenchyma, often with the appearance of well-defined nodules representing cysts. It is important to realize that not only microscopically but also radiographically the borderline between normal and pathological is not well-defined. The radiologist should hesistate before diagnosing fibrocystic disease. We do not make this diagnosis unless there is a nodular breast parenchyma on physical examination combined with a dense breast parenchyma and cyst-like lesions on the mammogram (Fig. 16). Due to its frequency it may also be wise to use the term fibrocystic changes rather than disease.

On a properly positioned oblique view one can usually identify one or several lymph nodes in the lower axillary region. Lymph nodes may be seen anywhere in the breast, although by far most frequently in the upper outer quadrant, along the lateral thoracic artery and veins. Normal

 

a	Figure 17. 58-year old woman who underwent conservative surgery of the right breast for invasive breast carcinoma. a) Oblique view of the normal left breast including several normal lymph nodes in the lower axilla, one of which is indicated by an arrow. b) The routine examination of the left breast two years later showing the same lymph node (arrow) which has increased in size and density. Furthermore, the area of fat infiltration in the hilum seen in a) has disappeared. Surgical biopsy confirmed the presence of metastasis from the contralateral breast carcinoma. c) 60-year old, asymptomatic woman with multiple pathologic lymph nodes seen on the oblique view of the left breast. Similar lymph nodes were seen on the right side. The patient had a history of rheumatoid arthritis and no evidence of breast carcinoma or other malignant disease.
b
c

lymph nodes are kidney-shaped, with fat in the hilum. Pathologic lymph nodes are usually rounded without fat in the hilum and often of relatively higher density (Fig. 17). Size per se is no indicator of abnormality. Normal lymph nodes may be several centimetres in size, when they contain much fatty tissue. Normal lymph nodes, smaller than 1 cm in 

Figure 18. 67-year old woman with a palpable mass in the right lower axilla. The oblique view of the right breast shows a tumor with an irregular, spiculated border. Microscopy of the surgical 5pecimen showed a primary breast carcinoma. No lymph node metastasis.

diameter, may be rounded without fat in the hilum. The radiographic appearance of pathologic lymph nodes is the same whether the process represents metastasis, lymphoma, or inflammation. A common cause of pathologic lymph nodes in the axilla is rheumatoid arthritis.
On a correctly positioned oblique view the pectoral muscle should be seen posteriorly at least down to the midplane of the breast. The muscle may be more or less striated due to fat infiltration. The breast parenchyma has a variable superior margin of extension and may reach high up towards the axilla and lateral to the pectoral muscle. Breast parenchyma may occur isolated in the axillary region and even simulate a malignant tumor on the mammogram. In the presence of a non-specific density in the axillary region, it is important to perform a physical examination and to evaluate the results with the mammogram. In the presence of ancillary normal breast tissue the patient often gives a history of premenstrual swelling and tension in the axillary portion of the breast. On rare occasions even an extra nipple can be seen in this area. An important consequence of this anatomic variation is that primary breast cancer can occur in the lower part of the axilla (Fig. 18).

a

Figure 19. a) A 72-year old woman with a palpable mass in the lateral portion of the left breast. Mammography shows a 3 cm lobulated tumor, mainly well circumscribed but with areas of indistinct border and a couple of thin extensions into the surrounding fatty tissue. The density of the tumor is relatively high. Microscopic diagnosis: Mucinous carcinoma. b) 62-year old woman who hadfelt a mass in her left breast. The mammogram shows a spiculated tumor with a diameter of approximately 2cm. Microscopy of the surgical specimen showed invasive ductal carcinoma.

b

Principles of mammographic differential diagnosis

It is useful to analyze breast lesions in terms of a few general categories, which often occur in different combinations:
1. Tumor, including so-called asymmetrical density
2. Architectural distortion
3. Calcification
4. Oedema

Tumor
There are two main categories of mass lesions according to their marginal characteristics: Circumscribed and not circumscribed (Fig. 19). A
well-circumscribed lesion carries a high probability of representing a benign tumor, while a mass with an irregular margin is usually malignant. Actually, the likelihood that a spiculated tumor represents a carcinoma

Figure 20. 39-year old patient who was referred because of a tumor in her right lung which turned out to be a hamartoma. She was asymptomatic from the breasts. The left mammogram shows an 8.0 cm lesion of variable density, surrounded by a capsule-like structure (arrows). On palpation, a soft, lens-like structure was felt. Radiographic diagnosis: Fibroadenolipoma (hamartoma).

is over 90 % provided postoperative changes can be excluded.

Most well circumscribed tumors represent a benign lesion like a simple cyst, fibroadenoma, lymph node, sebaceous cyst, papilloma, or hematoma. There are, however, exceptions in that carcinoma may present as a circumscribed mass. Also rare tumors like sarcoma and lymphoma usually present in this way.

Often the radiographic differentiation between benign and malignant circumscribed masses is difficult or impossible. Ultrasound is then useful in the differentiation between a solid and a cystic mass. However, once a mass has been shown to be solid, further differentiation is usually impossible by ultrasound.

In addition to the marginal characteristics of a tumor other radiographic features are sometimes helpful. The density is of some interest in that relatively low density of the tumor in relation to normal parenchyma is in favour of a benign lesion, while a relatively high density increases the probability of malignancy. It is important to stress that there are many exceptions: some carcinomas may be of relatively low density, and some cysts may be of high density. Mixed lesions with areas of fat density are practically always benign. Three types of lesions may contain a varying amount of fat: hamartoma (fibroadenolipoma) (Fig. 20), fatnecrosis, and

Figure 21. Asymptomatic 56-year old woman. The oblique view of the right breast shows several small rounded nodules along the lateral thoracic artery and vein. This is a typical location for lymph nodes.

galactocele. Hamartomas may also be homogeneously dense.

The presence of a halo strongly favours a benign lesion. A halo is a thin, radiolucent band around the tumor. Usually the halo cannot be seen all around the tumor. It should be noted that a halo may be seen around circumscribed malignant tumors on rare occasions. It has been debated whether a halo represents a so-called Mach band. However, from a practical standpoint the sign is useful.

The location of a circumscribed tumor may speak in favour of a benign lesion. This applies to a well-circumscribed nodule in the upper outer quadrant, especially if located dose to the vessels which, as mentioned before, is a typical location for lymph nodes. The region of the inframammary fold is the typical location of a sebaceous cyst. If this is suspected, tangential views should be obtained to demonstrate its dose relationship to the skin.

Another important parameter is multiplicity. If multiple well-circumscribed nodules or tumors are seen in the breast, they probably represent benign structures like cysts or possibly fibroadenomas (Fig. 16), or, if located in the upper outer quadrant, possibly lymph nodes (Fig. 21). One exception is metastatic disease which may present as multiple circumscribed

a	Figure 22. 52-year old woman with a palpable mass in her left breast. a) On the lateral view (horizontal beam) a corresponding lobulated well marginated tumor is seen. In two places sedimentation of calcium is seen. b) After almost complete aspiration of the cyst fluid and injection of air, intracystic tumor can be ruled out on the pneumocystogram.
b

nodules in the breast. A solitary circumscribed mass, especially in an older woman, carries a higher probability of malignancy.

In the presence of a solid, well-circumscribed mass in which malignancy cannot be ruled out radiographically, further investigation has to be performed. In this situation we use fine-needle aspiration biopsy. If the lesion is cystic the fluid may be aspirated and a pneumocystogram performed by replacing the fluid with air (Fig. 22) to exclude intracystic tumor. If there is no suspicion of intra-cystic tumor and if the cyst fluid is not bloody, cytologic examination of the fluid is unnecessary. Most cysts do not recur after pneumocystography.

A tumor with an irregular border, especially if spiculated, carries a much higher probability of malignancy as mentioned above. There are, however, a few differential diagnostic possibilities. By far the most important is postoperative changes. Usually, a surgical scar presents as an area of architectural distortion, but sometimes a scar may present as a tumor with surrounding spicules. This is especially true if there has been a complication like hematoma, seroma or abscess, perhaps further complicated by fat necrosis. Information on previous surgery should always be available to the radiologist. Blunt trauma to the breast may result in similar changes (Fig. 23). A word of caution: Occasionally, a patient with breast cancer will associate the tumor with a recent trauma. It is important

a

Figure 23. 60-year old woman with a palpable mass in the subareolar region of the left breast after blunt trauma to the breast. a) Six months after the trauma there is a 3 cm ill-defined, spiculated density. Cytology showed giant cells and other evidence of a post-traumatic lesion. b) Two years later the lesion has shrunk with the development of calcifications. Radiographic diagnosis: Post-traumatic lesion, probably with fat necrosis.

b

Figure 24. Asymptomatic 58-year old woman. The mammogram shows a small, ill-defined density with retraction of surrounding structures (centre of image). On cytology there was no suspicion of malignancy. Microscopy of the surgical specimen revealed a 3 mm radial sear.

for the referring physician and the radiologist not to be mislead by such a history.

Mastitis or abscess may present radiographically as a mass with an irregular border. It should be noted that mastitis is not always associated with obvious inflammatory signs clinically due to low-grade inflammation. Ultrasound and fine-needle aspiration biopsy usually provide valuable differential diagnostic information. The diagnosis of inflammation or abscess may also be obtained ex juvantibus, i.e. by treating the patient with antibiotics and repeating the mammogram after 3 to 4 weeks. A

Figure 25. 84-year old woman with a palpable mass in the left breast. The oblique view shows a spiculated tumor with retraction of the pectoral muscle as well as of the skin which is thickened (arrow). On histopathological examination of the mastectomy specimen a 2,6 cm invasive carcinoma was found. There was no tumor invasion in the skin or the pectoral muscle.

mastitis will usually regress substantially in this period of time.

In rare cases certain forms of fibrocystic disease may present as a spiculated lesion, as may also the so-called radial scar (Fig. 24) which will be described later.

In summary, lesions with an irregular and spiculated margin imply a high probability of carcinoma. A recommendation of surgical biopsy is, therefore, practically always appropriate.

There is some correlation between the mammographic appearance of carcinoma and the microscopic type. The irregular, spiculated border of many carcinomas is caused by reactive fibrosis. This type of carcinoma is hard on palpation and on the cut surface grey-yellow streaks representing elastin are often seen. The fibrotic reaction may extend far beyond the tumor itself, with thickening of connective tissue in the so-called Cooper's ligaments which are anchored to the skin (Fig. 25). Similarly, the periductal tissue in the subareolar region may be involved by reactive fibrosis. The fibrotic tissue characteristically undergoes shortening (retraction) with dimpling of the overlying skin and retraction of the nipple. This is the basis for important radiographic as well as clinical symptoms. Cancer with reactive fibrosis usually feels larger than its actual size. It should be note d that periductal fibrosis and nipple retraction can be seen with benign disease such as duct ectasia. In such cases the nipple retraction is most often bilateral and has almost always been noted by the patient for many years.

In contrast, the circumscribed type of carcinoma usually has much less reactive fibrosis, none or little elastin, no tubules and usually larger cells. The circumscribed type of ductal carcinoma is sometimes called ductal carcinoma of comedo-type. There is evidence that this type of breast cancer has a graver prognosis than ductal carcinoma productive of fibrosis. Altogether, the ductal carcinoma with productive fibrosis and ductal carcinoma of comedo-type comprise 70-80 % of all breast carcinomas. The less frequent special types of carcinoma like medullary with lymphoid stromal infiltration and mucinous carcinoma usually present as well-circumscribed tumors, while lobular invasive carcinoma usually has a spiculated appearance.

Asymmetrical density
This is a common problem in mammography. The vast majority of asymmetrical densities simply represent areas of asymmetrical normal glandular tissue or fibrocystic changes. If in doubt, the radiologist should obtain special views including magnification and coned down views to better demonstrate morphologic detail. Physical examination and correlation of physical findings and history with the mammogram are often useful. Hormone replacement therapy may sometimes explain a new asymmetrical density. A history of recent trauma may similarly explain a new asymmetrical density which thus may represent contusion of breast tissue. In the presence of a bloody discharge the asymmetrical density may represent an intraductal carcinoma.

There is reason to be cautious, if an area of asymmetrical density is new or has any characteristics which may imply malignancy, like calcifications, spiculation or architectural distortion, furthermore, if the patient has a bloody discharge or finally, if there is a suspicious finding on physical examination in the area of the asymmetrical density. It should be re-emphasized that an area of asymmetrical density in the absence of any tumor characteristics rarely represents carcinoma.

Architectural distortion
Architectural distortion may be defined as a disruption of the normal architecture of the breast without a dominating mass. This may be seen in malignant as well as benign disease. The most common explanation of architectural distortion is postoperative scarring. As was pointed out above, information on previous surgery should always be available to

a

Figure 26. 75-year old woman who sought advice because of a palpable mass in the left breast. a) The oblique view of the left breast shows an area of architectural distorsion (arrows) and an area of non-specific density. b) The normal right breast for comparison. On histopathological examination of the left breast a 2,1 by 0,8 cm tumor was found corresponding to the area of architectural distorsion seen in a). The microscopic diagnosis was invasive and non-invasive lobular carcinoma.

b

the radiologist. In addition to postoperative scarring there are two main differential diagnostic possibilities: carcinoma, and radial scar.
One particular microscopic type of carcinoma, invasive lobular carcinoma, sometimes presents as an area of architectural distortion without an evident tumor mass (Fig. 26). This may be explained by its propensity to grow multifocally and in single rows diffusely infiltrating the normal breast tissue. There may also be a varying degree of reactive fibrosis. US is often useful in these cases, demonstrating a hypoechogenic lesion, sometimes with multiple foci of shadowing.

A radial scar (infiltrating epitheliosis) is a benign lesion which is usually small and virtually always non-palpable. A radial scar has a stellate configuration with a fibrotic centre containing elastin deposits and tubular structures and surrounded by a corona of retracted ducts and lobules,

a

Figure 27. a) 76-year old asymptomatic patient. On the mammogram a coarse calcification is demonstrated in the subareolar region, relatively characteristic for a fibroadenoma. There is no soft tissue mass, which may be due to hyaline degeneration of the fibroadenoma, a common finding in elderly women. b) 69-year old asymptomatic woman. On the mammogram, a mixture of needle-like, globular and tubular calcifications are seen, characteristic for duet ectasia (plasma cell mastitis).

b

often containing epithelial proliferations and sometimes even intraductal carcinoma. Sometimes the centre of the lesion is relatively radiolucent, but basically, the les ion is not characteristic enough to allow a benign diagnosis (Fig. 24). Further, according to some pathologists, radial scars are potential precursors of carcinoma.

In summary, a surgical biopsy should always be recommended in the presence of architectural distortion, provided postoperative changes can be excluded.

Calcifications
This is a very common finding at mammography. The vast majority of calcifications are benign, and many of the benign calcifications can easily be classified as such. On the other hand, calcifications are sometimes the only radiographic sign of malignancy. This is especially true for early, non-invasive carcinoma, which is usually non-palpable. Calcifications are the main radiologic finding in 20 to 30 per cent of

a	Figure 28. 44-year old woman with premenstrual tenderness in the breasts. a) On the craniocaudal view smudges of calcification are seen. b) On the lateral view (horizontal beam) linear and curvilinear calcifications are seen, representing sedimentation of calcium in small cysts ("tea cups "). Radiographic diagnosis: Microcystic disease.
b

 

Figure 29. 60-year old asymptomatic woman. Incidental finding of a 2.4 cm well-marginated lesion with fat attenuation. The "capsule" is partly calcified. This appearance is characteristic for an oil cyst which occurs after fat necrosis. The lesion was palpable. The patient had a history of trauma to the breast from a safety belt five years prior to the current examination.

carcinomas detected on screening.

Characteristic, benign calcifications are often seen in fibroadenoma (popcorn like), ductectasia (needle like) (Fig. 27), microcystic disease (teacups) (Fig. 28), and sometimes in sclerosing adenosis. Various globular calcifications are also easily identified as benign (Fig. 29). Sometimes, however, calcifications in these benign diseases may be difficult to categorize correctly. This is especially true for the early stages of calcifications in fibroadenoma, fat necrosis, and fibrocystic disease and, sometimes in arteriosclerosis.

Figure 30. 73-year old woman with eczema on the right nipple. Physical examination of the breast was otherwise unremarkable. The magnification view (x 1,8) of the lateral portion of the right breast shows a 4 cm area of dense parenchyma containing numerous calcifications which vary in size, form and density. In some places there is a suggestion of ductal arrangement. X-ray guided FNAB showed malignant cells. Microscopy of the mastectomy specimen showed intraductal noninvasive carcinoma of comedo type with Paget's disease of the nipple. The axilla was free from metastases.

Calcifications should be analyzed as regards morphology (size, form and density), distribution (scattered or clustered), and arrangement (linear, lobular).

Benign calcifications tend to be scattered and rounded with a relatively uniform size and density. Malignant calcifications tend to vary in size, shape and density (Fig. 30). Lobular ca1cifications are usually arranged in rounded groups, while calcifications of ductal origin tend to be arranged in groups with an irregular outline. Linear or branching configuration of the calcifications is an important indicator of a ductal origin.

The most characteristic type of malignant calcifications are those associated with intraductal carcinoma (ductal carcinoma in situ - DCIS), which is usually subdivided into the comedo- and non-comedo types. The most typical calcifications are seen with the comedo-type in which dystrophic calcifications are formed in necrotic material in the centre of dilated ducts. Other growth patterns of DCIS such as cribriform or micropapillary, are usually associated with less characteristic calcifications or no calcifications at all.

Basically, invasive disease cannot be ruled out on the basis of a mammogram. The greater the extent of the calcifications, the higher the probability of microinvasion, even in the absence of a soft tissue mass. In the presence of a soft tissue mass or retraction, invasive disease must be suspected (Figs. 31, 32). Also, the extent of the disease is often greater than

Figure 31. 64-year old, asymptomatic woman undergoing screening mammography. Physical examination was unremarkable. The magnification view (x 1,8) shows irregular calcifications in an area with architectural distorsion (retraction). Evident ductal arrangement of same of the calcifications. On the basis of the mammogram invasive carcinoma combined with DCIS was suspected. FNAB revealed atypical cells, suspicious for carcinoma. Microscopy of the surgical specimen showed a 1.0 cm invasive carcinoma with extensive intraductal component of mixed comedo and cribriform type Three metastatic nodes in the axilla.

Figure 32. 63-year old woman with a palpable mass in the left breast. The magnification view (x 1.8) shows a 2.2 cm mainly well marginated mass with extensive calcifications in as well as outside the tumor. Evident ductal arrangement in several areas. FNAB showed cancer cells. Microscopic examination of the surgical specimen revealed an invasive carcinoma with extensive intraductal component involving ducts adjacent to the tumor and into the nipple. No metastases in the axilla.

the extent of the calcifications. This is especially true for the non-comedo types of DCIS.

It should be mentioned that lobular carcinoma in situ (LCIS) is not a radiographic diagnosis. LCIS occasionally found in biopsies performed for clustered calcifications is usually an incidental finding, the calcifications representing fibrocystic or other benign disease.

With experience it is possible to make rough estimates of the probability of carcinoma for broad categories of calcifications. Table 1 shows an example of a classification of calcifications into four risk groups, based on 213 biopsies of clustered calcifications.

As a rough rule, we consider clusters of five or more irregular calcifications as suspicious for carcinoma. It should be understood that five is

Table 1.Radiographic appearance of clustered calcifications and risk of malignancy

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Risk group	Radiographic characteristics of calcifications	Proportion of biopsies with breast carcinoma *
		N%
1.	a) rounded b) "cloudy" c) "tea cups"	0/54	0
2.	as in risk group 1, but with some irregular calcifications	13/75 17	17
3.	a) irregular, few b) possible ductal arrangement	22/58	38
4.	a) irregular, abundant b) definitive ductal arrangement	25/26	96

---

Modified after Sigfússon, Andersson et al. 1983

*) 10 cases of LCIS which were incidental findings in areas adjacent to benign calcifications were excluded, 3 in risk group 1,5 in group 2, and 2 in group 3.

not a magic number. More important is the morphology and arrangement of calcifications. A ductal or branching configuration of the calcifications substantially increases the probability of carcinoma. Magnification views should virtually always be obtained to allow the study of morphologic detail. It should also be understood that the size of the cluster is of no diagnostic significance. A cluster of malignant calcifications may be a few millimetres in diameter or the calcifications may involve more than one quadrant. In our institutions, FNAB is included in the further work-up of patients with clustered calcifications. Borderline clusters with negative cytology are usually followed at intervals of six and twelve months. For more suspicious calcifications with a higher degree of suspicion a surgical biopsy is recommended irrespective of the result of cytology. In the presence of a definitive cytologic diagnosis of carcinoma a segmental resection is usually performed, if the calcifications are limited to one quadrant.

Oedema
Radiographically, oedema of the breast is characterized by an increased trabecular pattern in the subcutaneous tissue, skin thickening and

Figure 33. 88-year old woman with a clinical diagnosis of mastitis or abscess in the lateral portion of the right breast. The craniocaudal projection shows increased density, skin thickening and a trabecular pattern in the subcutaneous tissue in the lateral portion of the breast (left portion of the image). FNAB was negative for malignancy. Complete resolution after treatment with antibiotics. Final diagnosis: Mastitis with oedema of the breast.

generally increased density in the breast (Fig, 33). The pathophysiologic basis for these changes is veno-lymphatic obstruction which may be caused by angiolymphatic growth of cancer in the breast, inflammation of the breast (mastitis), obstruction of the lymphatic drainage in the axilla from metastatic disease, postirradiation reaction, or obstruction of the draining veins including the superior vena cava. This means that oedema of the breast can be se en with a variety of benign and malignant diseases.

In practice the most common cause of oedema of the breast is previous breast irradiation. Postirradiation oedema is usually most pronounced after 6-12 months, and it tends to regress gradually thereafter.

Sometimes oedema is the only radiographic sign of carcinoma of the breast, but often the malignant tumor or calcifications are also evident. Usually there are enlarged lymph nodes in the axilla. Some, but not all of these patients present as so-called inflammatory carcinoma, which, however, is a clinical diagnosis and should usually not be made on the basis of radiograms. On the other hand, mammography is more sensitive than clinical examination in detecting oedema.

Any disease causing generalized oedema of the body such as cardiac failure or hypoalbuminemia due to liver failure can cause oedema of the breast. Although such oedema is usually bilateral, it may be unilateral,

a

b

Figure 34. 67-year old woman who underwent screening examination. a) A somewhat spiculated 0.5 by 0.6 cm tumor was detected in the upper outer quadrant of the left breast (arrow), highly suspicious for malignancy. The patient refused further investigation and treatment. She returned almost three years later with a palpable mass in the upper outer quadrant of the left breast. Repeat mammogram (b) shows that the tumor has grown substantially, now measuring 2.5 x 2.0 cm. Microscopic examination of the mastectomy specimen showed invasive carcinoma of the comedo-type and 14 metastatic nodes in the axilla, all with periglandular growth.

if the patient is bedridden and lying on one side.

Rarely, amalignant process in the mediastinum may cause venous obstruction with oedema of one or both breasts as a result.

In the presence of oedema of the breast without obvious reason, it is wise to perform a physical examination and obtain a clinical history which will often give a clue to the correct diagnosis.

 

 

Ingvar Andersson and Baldur F. Sigfússon