CASE 1
History: A 40-year-old woman presents for a baseline screening mammogram.
1. What is a screening population? (Choose all that apply.)
B. Patients with a lump that has been assessed as benign by the primary care provider
C. Patients with a nipple discharge on only one side
2. What is a diagnostic population?
A. Patients with a strong family history of breast cancer
B. Patients with a lump or nipple discharge
C. Patients with chronic cyclic breast pain
D. Patients who are extremely anxious about breast cancer
3. What is prevalence screening, and what is the approximate cancer detection rate in this population?
A. Patients who have ovarian cancer; 15/1000
B. Patients with a family history of breast cancer; 12/1000
C. First round of screening, no prior mammogram; 6-10/1000
D. Patients who have had many years of screening
4. What is incidence screening, and what is the approximate cancer detection rate in this population?
A. Screening in women who have had no prior mammogram; 10/1000
B. Screening in women undergoing annual mammography; 2-4/1000
D. Screening in high-risk women
ANSWERS
CASE 1
Incidence and Prevalence
1. A and D
2. B
3. C
4. B
References
Bassett LW, Jackson VP, Jahan R, et al. Diagnosis of Diseases of the Breast. Philadelphia: Saunders; 1997.
Cross-Reference
Ikeda D. Breast Imaging. THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010. p 39
Comment
The incidence of breast cancer is an estimate of the number of new cases of breast cancer over a specific period. It can also be stated as the incidence rate, which is the number of people with a diagnosis of breast cancer per 100,000 people. In the United States in 2008, the incidence rate of breast cancer in all women undergoing screening was 3/1000 women. This number reflects new cancers not previously detected.
The prevalence of breast cancer refers to the number of women living with breast cancer at any given time. Prevalence screening is the first mammogram performed in previously unscreened women, and the rate of cancer detected in average-risk women in this first screening event is higher than the incidence rate, at approximately 6 to 10 women with cancer detected per 1000 screens.
Mammography exams are divided into two broad types: screening and diagnostic exams. The screening exam consists of four standard imaging views (mediolateral oblique [MLO] (see the figure) and craniocaudal [CC] view of each breast), and the population is women who have no signs or symptoms of breast cancer. This group includes women who might have an increased risk of breast cancer because of family history. It also includes women with breast pain, which is not considered to be a symptom of breast cancer, particularly if the pain waxes and wanes. Exams of asymptomatic women with implants are also typically considered to be screening. Women with implants have an additional four views performed, with a special maneuver to displace the implants. This is to better visualize the breast tissue anterior to the implant.
Screening mammograms are often read in batches after the patient has left the department. If the exam is considered incomplete, she needs to be recalled for additional evaluation at a later time.
The diagnostic exam is tailored to an abnormality. If a patient presents with a clinical sign or symptom of breast cancer, such as a lump, nipple discharge, or red, swollen breast, the technologist typically marks the area of concern with a radiopaque marker and then performs the standard imaging mammographic views, as well as additional views to better image the area of concern. These views may include spot compression, magnification, tangential, 90-degree lateral, or rolled craniocaudal views. Ultrasound may also be performed for more complete evaluation. The diagnostic exam is directed by the radiologist, and results are given to the patient before she leaves.
CASE 2
History: A 72-year-old woman presents for her first mammogram because of reduced mobility in her left arm and a draining wound in her left breast.
1. What should be included in the differential diagnosis? (Choose all that apply.)
B. Left breast infection, right breast cancer
D. Bilateral metastatic disease
2. What are the American Cancer Society and American College of Radiology guidelines for screening mammography in normal-risk women age 40 and older?
A. Baseline mammogram at age 35, then annual mammograms thereafter
B. Begin at age 40, then every other year until age 50, then annual
C. Begin at age 40, then every year until age 75
D. Begin annual screening at age 40
3. What is the reported reduction of breast cancer mortality associated with routine screening?
4. What is the incidence of breast cancer for women in the United States?
A. 1 in 15 women over a woman’s lifetime
B. 1 in 5 women over a woman’s lifetime
C. 1 in 8 women over a woman’s lifetime
D. 1 in 10 women over a woman’s lifetime
ANSWERS
CASE 2
Screening Guidelines
1. A and B
2. D
3. D
4. C
References
Cross-Reference
Ikeda D. Breast Imaging. THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010. p 1
Comment
The goal of screening mammography is to detect breast cancer as occult disease—before the patient and clinician know it is there. In this patient, her baseline mammogram, performed at age 72, was prompted by the presence of a large, ulcerating mass in her left breast, with bulky left axillary adenopathy. A small cancer is incidentally noted in the contralateral breast. This case illustrates the benefit of screening: The small right breast mass is detected on mammography before it is detected clinically; the locally advanced left breast cancer was detected late (see the figure). Had this patient started routine annual screening mammograms at an earlier age, it is likely that the left mass would have been seen earlier before it was found clinically. This patient had local spread of cancer to the skin and axillary nodes and widespread distant metastases at diagnosis.
Early detection is the attempt to find breast cancer before it has spread beyond the breast, improving morbidity and mortality from breast cancer. Mammography has been shown to decrease mortality from breast cancer by 30%, based on more recent data from the Swedish Two-County trial, including 130,000 women followed for 25 years.
Women in the United States have a slightly less than 1 in 8 lifetime risk for developing invasive breast cancer. The chance of dying from breast cancer is decreasing and is now approximately 1 in 35. The American Cancer Society estimated that there were 230,480 new cases of invasive breast cancer in 2011. This number is increasing and does not include carcinoma in situ. The American Cancer Society estimated that 57,650 new cases of in situ carcinoma were found in 2011. In 2011, 39,520 deaths from breast cancer were estimated to occur. This number is decreasing, likely owing to earlier detection and more effective treatments.
The American Cancer Society more recently updated their recommendations for screening for breast cancer: annual mammograms beginning at age 40 and continuing as long as the woman is in good health. They recommend clinical breast examination about every 3 years for women in their twenties and thirties and annually for women 40 and older. The American Cancer Society added that women should know how their breasts normally look and feel and that they should report any change to their health care provider; this might be termed breast awareness rather than breast self-examination. Guidelines have been also established for the screening of high-risk women.
CASE 3
History: A 66-year-old asymptomatic woman presents for routine screening.
1. What are the three most important risk factors for developing breast cancer?
C. Family and personal history of breast cancer
E. Known inherited gene mutation
2. How does estrogen play a role in breast cancer risk?
A. Estrogen stimulates the development of breast ducts and affects cell division.
B. Women who have late menarche and early menopause are at greater risk.
D. Taking exogenous estrogen does not increase the risk of breast cancer.
3. What percentage of breast cancers is due to known genetic mutations?
4. How do benign breast biopsies affect breast cancer risk?
A. There is no relation between benign breast biopsy and cancer.
B. Some lesions that are biopsied contain atypical cells that might be a precursor to cancer.
C. There is about a 10-fold increase in breast cancer risk with certain benign biopsy results.
ANSWERS
CASE 3
Risk Factors
1. A, B, and C
2. A
3. D
4. B
References
Bassett LW, Jackson VP, Jahan R, et al. Diagnosis of Diseases of the Breast. Philadelphia: Saunders; 1997. p 308
Evans DG, Howell A. Breast cancer risk-assessment models. Breast Cancer Res. 2007;9(5):213.
Cross-Reference
Ikeda D. Breast Imaging. In: THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010:24.
Comment
The most important risk factor for developing breast cancer is being female. Males have a low incidence and have approximately 1% of the total of breast cancers diagnosed. The second most important risk factor is increasing age. Risk steadily increases as the woman ages. Exposure to estrogen is an important risk factor, because estrogen influences cell division and breast duct development. The figure shows a suspicious mass in the right breast seen on a routine screening mammogram.
The longer the exposure to estrogen, the greater the chance of breast cancer, so women who begin menses early and who have a late menopause have higher risk. Women who have no pregnancies are at higher risk. The late timing of the first pregnancy also is thought to increase risk, because the developing breast of the adolescent and young adult has a longer exposure to estrogen. Estrogen supports the growth of estrogen-sensitive tumors.
Family history of breast cancer is an important risk factor, although the majority of women with breast cancer have no family members affected. Family history is present in approximately 25% of cancers diagnosed. The more important family members to assess in risk determination are the first-degree relatives: mother, sister, daughter, father, brother, and son. Second-degree relatives—grandmother, grandfather, aunt, and uncle—also play a role in risk, but to a lesser degree. The age of the relative is also important: The younger the age of the relative at diagnosis, the more significant the risk. Multiple premenopausal women with breast cancer in the family raises the concern for a possible gene mutation. Other factors include the presence of male breast cancer in the family and Ashkenazi Jewish heritage.
The two most common known genetic mutations are BRCA1 and BRCA2. Having one of these two mutations significantly increases the likelihood of developing breast cancer; breast cancer is 50% to 85% more likely to be diagnosed in a woman with either mutation in her lifetime. Recent data suggest that women who have a 20% or greater lifetime risk of breast cancer by a risk-assessment model should be screened with MRI as well as mammography annually. Risk-assessment models are available to practitioners and patients. The Gail, Claus, and Cuzick-Tyrer models are commonly used.
Breast cancer is thought to develop stepwise, through abnormalities in cell proliferation, so that normal cells develop into atypical hyperplasia, then into in situ cancer, then into infiltrative cancer. An abnormality that is detected in screening or by palpation and that is shown to be proliferative on histology confers an increased risk of developing cancer in that patient of 1.5 to 2 times, even though the lesion itself is benign. These lesions include sclerosing adenosis, papillomatosis, complex fibroadenoma, and hyperplasia without atypia. If the lesion is atypical hyperplasia, either lobular or ductal type, the risk increases to 4 to 5 times her normal risk.
CASE 4
History: An asymptomatic 42-year-old woman presents for a routine screening mammogram.
1. What is in the differential for diagnosis, tissue density, and Breast Imaging Reporting and Data System (BI-RADS) code of the mammogram views presented? (Choose all that apply.)
A. Normal fatty breast, BI-RADS 1
B. Indeterminate calcification in left breast, dense, BI-RADS 0
C. Dense breasts with punctate calcification in both breasts, BI-RADS 2
D. Normal dense breasts, BI-RADS 1
2. The descriptor of tissue density “scattered fibroglandular densities” corresponds to what percentage of gland tissue on the mammogram?
3. What is the MQSA?
A. Mammography Quality Standards Act
B. A state-by-state law, not federally mandated
C. A voluntary system for accreditation of mammography centers.
4. Why is the BI-RADS code important?
B. Although it is not mandated by law, it is good medical practice.
C. It helps speed the interpretation of the mammogram.
ANSWERS
CASE 4
The Mammogram Report
1. C and D
2. C
3. A
4. A
References
American College of Radiology: Breast Imaging Reporting and Data System. Reston, VA, American College of Radiology, 2003
Cross-Reference
Ikeda D. Breast Imaging. In: THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010:39.
Comment
The mammogram report should follow a standard format, which includes the following elements:
1. Reason for exam—screening (routine) versus diagnostic (problem solving)
2. Tissue density (breast composition)
A. Almost entirely fat (<25% glandular)
B. Scattered fibroglandular densities (25% to 50% glandular)
C. Heterogeneous dense, which could obscure detection of small masses (50% to 75% glandular)
3. Description of any significant findings
B. Calcifications (which may be scattered and punctate, as in the figure)
4. Comparison to previous exam, if available
5. Impression; include BI-RADS categories
B. BI-RADS 2—benign finding(s) (as in the mammogram in the figure)
C. BI-RADS 3—probably benign (<2% chance of malignancy)
D. BI-RADS 4—suspicious abnormality, biopsy should be considered
E. BI-RADS 5—highly suspicious, appropriate action should be taken (>95% chance of malignancy)
The inclusion of a recommendation at the end of the report is good medical practice. This should state if the patient is to have her next mammogram at the standard interval, needs a follow-up at a short interval, needs additional views, or needs a biopsy.
Screening mammography results should be limited to normal (BI-RADS 1 or 2) or incomplete (BI-RADS 0), needs more evaluation. BI-RADS 4 or 5 is not given at screening. Suspicious findings should be further evaluated with additional views before rendering a final impression. BI-RADS 3 is used after the full evaluation has been performed and the finding is a small chance of malignancy (<2%), and a short-interval follow-up is recommended.
CASE 5
History: Screening mammograms.
1. What is your differential diagnosis for the four different patients? (Choose all that apply.)
B. Normal mammograms with four different tissue densities
2. Why is it important to report the tissue density in the mammogram report?
A. The breast density reflects your confidence in excluding cancer.
B. The mammogram is not very sensitive in detecting cancer in the fatty-replaced breast.
C. It is required by the Mammography Quality Standards Act (MQSA).
D. It is a very precise way of describing the character of the breast tissue.
3. How does the breast density affect the sensitivity for detecting breast cancer on the mammogram?
A. Breast cancer sensitivity is highest in the fatty breast.
B. Sensitivity is highest in the dense breast.
C. Sensitivity is lower when the density is lower.
D. Breast density is not related to mammographic sensitivity.
4. Does breast density change over the woman’s life?
A. No, breast tissue density is inherent, and it is stable over time.
B. Yes, the breast becomes denser as the woman ages.
ANSWERS
CASE 5
Breast Tissue Density Examples
1. A and B
2. A
3. A
4. C
References
American College of Radiology. Breast Imaging Reporting and Data System (BI-RADS). Reston, VA: American College of Radiology; 2003.
Cross-Reference
Ikeda D. Breast Imaging. In: THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010:29.
Comment
Mammographic density is reported because it tells the referring physician the sensitivity of the mammogram in detecting breast cancer. In the fatty breast, the contrast between the background dark fat and the white tumor is the greatest; therefore, sensitivity for detecting cancer is the highest in this type of breast. In the dense breast, the background density is white, similar to the density of tumor, so a tumor can be missed.
The four-category system of breast density is as follows:
1. Almost entirely fat, <25% glandular
2. Scattered fibroglandular densities, 25% to 50% glandular
Dense breasts are seen commonly in young women, and the density can decrease with age. However, many young women do not have dense breasts, and postmenopausal women with no exogenous hormone use can have dense breasts. The density is also affected by lactation. During lactation the breast is commonly very dense. The patient’s weight can affect breast density. Typically, thin women have dense breasts, and obese women have fatty-replaced breasts. The sensitivity of the mammogram varies with the patient’s age and with breast density.
CASE 6
History: Routine mammogram in an 82-year-old asymptomatic woman with no history of breast surgery. She is not taking hormones.
1. What is your differential diagnosis for this patient, including BI-RADS diagnostic code? (Choose all that apply.)
A. Benign mammogram, BI-RADS 2
B. Focal asymmetric density in right upper posterior breast, BI-RADS 0
C. Heterogeneously dense breasts, BI-RADS 2
D. Dense breasts, advise screening MRI, BI-RADS 0
E. Suspicious calcifications in left breast, BI-RADS 0
2. Does this breast density confer a higher risk of malignancy?
A. No, risk is not related to breast density.
B. No, her only risk factor is her age.
C. Yes, there is an increased risk of malignancy in women with dense breasts.
D. No, fatty breasts have the highest risk of malignancy.
3. Is this tissue density seen more often in premenopausal or postmenopausal women?
A. Dense breasts are more common in postmenopausal women.
B. There is no relation of breast density to menopausal status.
C. Breast density is related only to the degree of fat in the breast, not to menopausal status.
D. Dense breasts are more common in premenopausal women.
4. In the postmenopausal woman, is this density related to hormone therapy?
B. Yes, hormones can increase breast density.
C. Yes, but hormones cause increased density only in the upper outer quadrant of the breasts.
D. Yes, but it also always causes pain.
ANSWERS
CASE 6
Dense Breast in an 82-Year-Old Woman
1. A and C
2. C
3. D
4. B
References
Harvey JA, Bovbjerg VE. Quantitative assessment of mammographic breast density: relationship with breast cancer risk. Radiology. 2004;230:29–41.
Cross-Reference
Ikeda D. Breast Imaging. In: THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010:29.
Comment
Denser breasts are commonly seen in mammography. This type of mammogram is more difficult to interpret because the radiographic density of the glandular tissue and a mass or cyst is similar, meaning that masses may be obscured in a dense breast. The dense tissue on the mammogram represents the ducts and lobules and also fibrous connective tissue. In a dense breast, there is relatively little fat interspersed between the glandular elements.
Increased density imparted an increased risk of breast cancer in several studies using a quantitative measurement of breast density, with an odds ratio of 4.0 or greater, meaning that women with dense breasts had a fourfold increase in risk of breast cancer compared to those with the least dense breasts. Due to the breast density and advanced age, older women with dense breasts have an even higher risk.
Breast tissue is responsive to hormone changes. Estrogen levels are higher in younger women, and after menopause, estrogen levels diminish and cause the breast lobules to regress. The mammogram then becomes less dense. About 65% of women in their twenties have at least 50% breast density. This decreases to 50% of women in their forties and to 30% of women in their seventies. Therefore, this relatively dense breast is uncommon in older women.
Hormone replacement therapy increases the glandular density of the breast in up to 73% of women, and the greatest increase in density occurs in the first year of use. This increase in density is due to stimulation of the cells of the ducts, lobules, and stroma to proliferate and increase mitotic activity.
The 82-year-old patient reported here is not on hormone replacement therapy, and the mammogram is unchanged compared to previous exams.
CASE 7
History: Left mediolateral oblique (MLO) mammograms of a 55-year-old woman taken 1 year apart. On the day of the later exam, she complains of bilateral breast tenderness and swelling.
1. What is your differential diagnosis for the change in the mammogram of this patient? (Choose all that apply.)
C. Hormone replacement therapy
D. Typical changes of menopause
2. What personal history question is typically asked of the patient who comes in for a mammogram?
B. History of clotting function
C. Family history of renal and liver disease
3. What would you do next to work up the patient’s symptoms and the change in the mammogram?
A. MRI is needed for more complete evaluation.
B. Take a clinical history regarding exogenous hormone use and any focal findings.
C. Nothing; this is normal for this age.
4. What is your recommendation for management of this patient?
A. Exogenous hormone therapy should be stopped because of the change on the mammogram.
C. Recommend routine mammography.
D. The patient should have needle biopsy of random sites in both breasts.
ANSWERS
CASE 7
Hormones
1. A, B, C, and E
2. A
3. B
4. C
References
Berkowitz JE, Gatewood OM, Goldblum LE, Gayler BW. Hormonal replacement therapy: mammographic manifestations. Radiology. 1990;174:199–201.
National Cancer Institute: Menopausal hormone replacement therapy use and cancer (factsheet)
Cross-Reference
Ikeda D. Breast Imaging. In: THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010:392.
Comment
The breasts bilaterally show an increase in density, although only one view is shown here (see the figures). The density is now “heterogeneously dense,” whereas before the density was “scattered fibroglandular densities.” The most common cause of bilaterally symmetric increasing density that involves the glandular tissue and not the skin (no edema or skin thickening) is exogenous hormone therapy (HRT), as in this case. The patient had begun taking a combined estrogen and progesterone supplement.
Normally, as a woman enters menopause, involutional changes occur in the breast parenchyma (see the figures). The volume of the mammographically dense areas tends to decrease as the glandular elements involute and are replaced by fat. HRT reverses the normal involution, and histologically the breast epithelium and stromal elements proliferate. This is due to the effects of the estrogen component of the HRT. The progesterone effects include an increase in epithelial mytotic activity and lobular hyperplasia.
These effects have been shown to increase the incidence of breast cancer in the postmenopausal population taking exogenous hormones, particularly combined therapy. In 2002, the Women’s Health Initiative (WHI), a study of exogenous hormone use, found an additional eight cases of breast cancer per 10,000 women in women on combined hormonal therapy for 1 year, compared to the placebo group. The choice to remain on hormone therapy is up to the patient and her clinician, and mammography is not typically performed at any different schedule because of this increased risk.
The imaging evaluation is based on the clinical findings. Ultrasound is not indicated when there is a diffuse bilateral increase in density when it can be explained by exogenous hormonal therapy. In our practice, we do not generally perform ultrasound on women who have bilateral diffuse breast pain. If there is a focal area of tenderness or an area of palpable concern, a directed ultrasound is performed. Occasionally, the mammographic and clinical findings are more unilateral and focal, in which case physical exam, directed ultrasound, and possibly MRI may be needed to exclude a developing malignancy.
CASE 8
History: A 40-year-old woman presents for routine screening mammogram. The first figure is the right mediolateral oblique (MLO) view 4 years earlier, when she had presented with a palpable lump. The second figure is the current exam.
1. What is your differential diagnosis for the difference in the appearance of the mammogram between the two exams? (Choose all that apply.)
A. The patient gained weight, causing more fat to develop in the breast.
B. The patient began taking birth control pills.
C. The patient was lactating on the earlier exam.
D. The patient had inflammatory breast cancer on the initial image, which was successfully treated.
2. Can you be sure this is the same patient? What can you do to try to verify the patient’s identity when reading mammograms?
A. Check the patient’s name on the image because this will always be correct.
B. Check for unique patterns of blood vessels and lymph nodes on the image.
C. Ask the patient if this is her previous mammogram.
D. When the appearance of the glandular tissue is very different, assume it is not the same patient.
3. Why was only one view performed when the patient presented with a palpable lump?
A. Mammography is limited during lactation, owing to breast density.
B. Mammography is dangerous to the infant being nursed, owing to radiation exposure.
C. Ultrasound alone can be used to evaluate the finding in all cases of palpable masses.
4. Why is mammography used at all for a lactating patient?
A. It should not be used in this situation.
B. Even though a woman is lactating, she should still have routine screening mammograms.
D. If the ultrasound exam demonstrates a simple cyst, mammography must also be used.
ANSWERS
CASE 8
Lactational Change
1. A, B, and C
2. B
3. A
4. C
Reference
Ahn BY, Kim HH, Moon WK, et al. Pregnancy- and lactation-associated breast cancer: mammographic and sonographic findings. J Ultrasound Med. 2003;22:491–497.
Cross-Reference
Ikeda D. Breast Imaging. In: THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010:378.
Comment
This 40-year-old woman presented for a routine mammogram. Her prior exam was made available for comparison, yet it is not at all similar to the current exam. It is important to verify the identity of the patient when interpreting studies, because human error can result in the wrong patient’s name on the exam. In this case, this is her prior exam, and the breast appearance is different because of lactation. This case illustrates the difficulty that can occur in interpreting the mammogram during lactation. During lactation, milk is produced by the lobules and carried in the ducts, which can increase the size and density of the breast, as in this case (see the figures). There is no danger to the nursing infant in performing mammography during lactation.
Ultrasound is often used as the initial exam for evaluating a palpable mass during lactation. If ultrasound demonstrates a simple cyst or a benign-appearing lactating adenoma or other benign mass that corresponds to the palpable finding, no mammogram is indicated. However, if the ultrasound is negative, mammography should be performed for more complete evaluation, essentially to check for a suspicious mass or microcalcifications (which are not present in this patient). If ultrasound demonstrates a suspicious mass, then mammography should be performed to check for extent of disease, such as microcalcifications or additional masses.
CASE 9
History: A 64-year-old woman with keloids from prior benign surgery presents for a routine screening mammogram. Right mediolateral oblique (MLO) and craniocaudal (CC) views are shown (see the first two figures). The patient returns for a right mammogram when she palpates a lump. Right MLO and CC views are shown from the second mammogram (see the second two figures).
1. What should be included in the differential diagnosis of the two sets of mammograms of the right breast? (Choose all that apply.)
A. Suspicious mass at 9 o’clock position, not present on first mammogram
B. Benign-appearing mass in the 4’clock position, new since previous mammogram
C. Suspicious mass at 1 o’clock position
D. Benign mass at 1 o’clock position
2. What is the posterior nipple line?
A. A line connecting the nipples on three views of the same breast
B. An imaginary line connecting the nipple to the posterior chest wall
C. A line drawn parallel to the chest wall, at the level of the nipple
D. A line drawn to measure the distance from the nipple to a lesion
3. If you think that screening mammographic views are not correctly positioned, what is the next step?
A. The patient should be recalled for proper positioning.
C. The radiologist should make a note in the report that positioning is suboptimal.
4. What is the next step in management of this patient?
ANSWERS
CASE 9
Poor Positioning, Missed Cancer
1. C and D
2. B
3. A
4. C
References
Eklund GW, Cardenosa G. The art of mammographic positioning. Radiol Clin North Am. 1992;30(1):21–53.
Cross-Reference
Ikeda D. Breast Imaging. In: THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010:6.
Comment
In this patient, a mass was seen only after she presented with a palpable lump. It was not recognized on the routine mammogram performed earlier because of inadequate positioning.
Proper positioning is an important part of breast imaging. It requires constant diligence on the part of the radiologic technologist and cooperation by the patient. Positioning must be evaluated by the radiologist on every examination. If positioning is inadequate, the patient needs to be recalled to have a well-performed mammogram, and the technologist needs to be informed that the positioning was not done to satisfaction.
The posterior nipple line is a way to assess the proper positioning of the mammogram. An imaginary line is drawn from the nipple to the chest wall or edge of the MLO image, perpendicular to the pectoral muscle (see the figures). This line is then drawn on the CC view, from the nipple to the edge of the then image. The length of the line on the CC view should be within 1 cm of the length of the line on the MLO view. In this case, it is not; the CC view is short. The mass present in the medial aspect of the breast was not included on the examination.
CASE 10
History: An asymptomatic woman presents for a routine screening mammogram.
1. A single right mediolateral oblique (MLO) view is shown in the first figure; repeat right MLO view is shown in the second figure. What is your one best reason for recalling this patient for an additional right MLO view?
A. The right breast MLO view is poorly positioned.
B. Microcalcifications in the breast need to be evaluated.
C. The first view has motion blur.
D. A possible mass in the central right breast needs to be evaluated.
2. Where is motion blur most likely to occur?
A. On the craniocaudal (CC) view
B. In the upper aspect of the breast
3. How can motion blur best be avoided?
A. Minimize the length of exposure.
D. Perform a “true lateral” view instead of an MLO view.
4. What is a technical recall?
B. A patient is recalled for magnifications or spot compression views.
C. The patient cannot tolerate compression.
D. The patient has never had a mammogram before.
ANSWERS
CASE 10
Motion Unsharpness
1. C
2. D
3. A
4. A
References
Bassett LW. Clinical image evaluation. Radiol Clin North Am. 1995;33(6):1027–1039.
Eklund GW, Cardenosa G. The art of mammographic positioning. Radiol Clin North Am. 1992;30(1):21–53.
Cross-Reference
Ikeda D. Breast Imaging. In: THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010:6.
Comment
Technical aspects of a good-quality image of the breast include positioning, compression, exposure, sharpness, noise, artifacts, and contrast. This case demonstrates motion unsharpness in the right MLO view (see the figures). The repeat image (see the figures) reveals sharper detail. Motion unsharpness can result when the patient moves during the exposure, and inadequate compression can contribute to it. This type of motion unsharpness often occurs in the inferior aspect of the breast on the MLO view, and it can be recognized by poor separation and blurriness of the edges of linear structures and tissue borders. This can be difficult to recognize, but it is important, because malignancy can be missed owing to unsharpness of the image. This is particularly true for microcalcifications and small masses. Compression thickness is greater on the MLO view than on the craniocaudal (CC) view, and it is more common to see motion unsharpness on the MLO view. Adequate compression immobilizes the breast and decreases the likelihood of motion unsharpness, reduces breast thickness, and reduces the dose needed for a proper exposure. If blur is seen, mammographic detail is compromised, and the image is not adequate for interpretation. The patient should be recalled for a repeat image (“technical recall”).
CASE 11
History: A 40-year-old woman presents for a baseline screening mammogram.
1. What should be included in the differential diagnosis, based on the four-view screening mammogram? (Choose all that apply.)
B. Malignant mass in the left medial breast
C. Benign mass in the left medial breast
D. Cyst in the left medial breast
2. What is the next step in the evaluation?
A. Recommend routine screening mammogram in 1 year.
B. Recall for additional spot compression views and ultrasound.
C. Perform MRI of the left breast.
D. Refer patient to a surgeon.
3. Why is the mass seen better on the craniocaudal (CC) view?
A. The finding is a superimposition of densities, not a true mass.
C. Typically, the medial breast is not included well on the MLO view.
D. The CC view is better positioned.
4. What are Tabar’s “danger zones”?
A. Areas of the world in which it is dangerous to practice breast imaging
B. Areas of the mammogram that are most likely to contain malignancy
C. Areas of the breast that are more likely to have malignant spread to the lymph nodes
D. Areas of the breast that are usually normal fat and to which special attention should be paid
ANSWERS
CASE 11
Medial Mass
1. B, C, and D
2. B
3. C
4. D
References
Eklund GW, Cardenosa G. The art of mammographic positioning. Radiol Clin North Am. 1992;30(1):21–53.
Cross-Reference
Ikeda D. Breast Imaging. In: THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010:38.
Comment
Masses or densities in the medial breast are in what is termed a “danger zone.” Typically, only fat and minimal gland tissue is seen in this area. The other “danger zones” include the retroglandular fat and the edge of the image. This case illustrates two of these “danger zone” findings: a mass in the medial breast (see the figures) and a mass that is just barely seen at the edge of the image on the MLO view (see the figures).
Most of the gland tissue of the breast is in the upper outer quadrant. For this reason, the MLO view was designated a standard view, rather than the orthogonal mediolateral view. The MLO view includes the upper outer quadrant more completely. However, the medial breast is not as well seen on the MLO view. For this reason, the medial breast must be included on the CC view as completely as possible. Medial masses seen on the CC view may not be seen on the MLO view because of the relative limitation of the MLO view in the medial breast. Focal densities seen only on one view, in the medial breast on the CC view, should be viewed with suspicion. Additional imaging should be performed.
This patient was recalled for spot compression views and ultrasound. The mass was seen on both spot compression views, and ultrasound showed a 17-mm solid mass in the 8 o’clock position of the lower inner left breast. The patient underwent a core needle biopsy, and histology showed a fibroadenoma.
CASE 12
History: Craniocaudal (CC) view from routine mammogram in two different women.
1. What is your differential diagnosis for the finding in the medial aspect of the CC view in these two different patients? (Choose all that apply.)
A. Abnormality in the pectoralis muscle
B. Sternalis muscle, a normal variant in some patients
2. What further work-up is performed next?
3. If there is a 5-cm mass in the medial breast on the CC view, does the differential diagnosis still include a sternalis muscle?
A. No, the sternalis muscle is typically less than 2 cm in cross section.
B. No, because the sternalis muscle is not located medially.
C. Yes, the finding could still represent the sternalis muscle.
4. Where is the sternalis muscle?
A. It is posterior to the pectoralis muscle and runs parallel to the pectoralis.
B. It is lateral to the sternum, running vertically, perpendicular to the pectoralis.
C. It is lateral to the pectoralis, running vertically in the mid-axillary line.
D. It runs parallel to the clavicle, adjacent to the sternum.
ANSWERS
CASE 12
Sternalis Muscle
Prior left CC view from patient 2.
1. B and D
2. A
3. A
4. B
References
Bradley FM, Hoover HC Jr. Hulka CA, et al: The sternalis muscle: an unusual normal finding seen on mammography. AJR Am J Roentgenol. 1996;166(1):33–36.
Cross-Reference
Ikeda D. Breast Imaging. In: THE REQUISITES. 2nd ed Philadelphia: Saunders; 2010:28.
Comment
The sternalis muscle is a variation of the chest wall musculature that is seen in approximately 8% of the population according to cadaveric studies. This muscle is long and narrow and runs vertically along the sternum at 90 degrees to the pectoralis muscle. It may be unilateral or bilateral; more often it is unilateral. It is seen in the far medial aspect of the breast on the CC view only, and it can be mistaken for a medial breast mass. It can have a rounded, triangular, or flame-shaped configuration, and it is usually surrounded by fat. It is typically less than 2 cm in diameter.
It is important to recognize this normal variant muscle (see the figures) and to avoid any additional work-up. Spot compression views and ultrasound are unrevealing, as is the physical exam. If the additional work-up is done and no mass is seen on ultrasound or felt on physical exam, and there is still diagnostic concern, cross-sectional imaging with CT or MR will demonstrate the sternalis muscle running perpendicular to the pectoralis, along the sternum. If prior mammograms are available, comparison can be helpful to observe the stability of the finding (see the figures).
The sternalis should be differentiated from the pectoralis muscle, which is present in nearly all patients, and the technologist should attempt to include the pectoralis on the CC as well as the mediolateral oblique (MLO) views, to demonstrate that the entire breast has been included in the image.
CASE 13
History: Craniocaudal (CC) views from screening mammograms in the same patient are presented.
1. What should be included in the differential diagnosis? (Choose all that apply.)
2. What is the next step in the work-up?
A. MRI to evaluate the chest wall
B. Breast-specific gamma imaging (BSGI) to evaluate for enhancing lesions
C. Spot compression views of the denser areas at the chest wall
D. Referring the patient to a surgeon for a physical examination
3. Is it desirable to position the breast so that the pectoralis muscle is included on the CC view?
A. No, there is no need to see the pectoralis muscle.
B. No, it is important only to see the glandular tissue and retroglandular fat.
C. No, the pectoralis muscle is seen only on the mediolateral oblique (MLO) view.
D. Yes, it is ideal to see the pectoralis muscle on the CC view.
4. How is the sternalis muscle different from the pectoralis muscle on the CC view?
A. It is ideal to include the sternalis muscle on every patient.
B. The sternalis and pectoralis muscles overlap and can be difficult to differentiate.
C. The sternalis muscle is seen in less than 10% of patients on a mammogram.
