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Special Populations in Breast Imaging
The Breast Imaging Reporting and Data System (BI-RADS) Atlas comprises a thorough and evidence-based guide for accurate image interpretation and management of most common clinical scenarios encountered in women 40 years and older. However, radiologists must also address the less common signs, symptoms, and concerns of unique populations, such as those who are younger, pregnant, lactating, male, or transgender. This chapter will outline a framework for navigating and meeting the needs of these special populations. The framework is derived from nearly all of the rules of image interpretation presented in the BI-RADS Atlas. Case examples are provided along with pearls and pitfalls to ensure imaging and management success. Supplemental evidence from the literature, along with special consideration of disease incidence relative to age, gender, and pregnancy, is incorporated to clarify best management practices.
The first consideration when approaching a concerned patient, particularly if they are younger, male, or a transgender woman, is the lower likelihood of breast cancer compared with female patients 40 years and older. Simply stated, a benign cause is more likely than breast cancer in these patients. The consequences, however, of missing a breast cancer in a young or male patient can be devastating. Uncommon clinical encounters combined with infrequent but serious diagnoses can elevate stress levels for everyone. The first rule for the radiologist is this: Do not panic. The second rule for the radiologist is this: Do not panic. The third rule for the radiologist is to listen to the patient. The fourth rule for the radiologist is to use the BI-RADS Atlas to correctly classify all imaging findings, and the fifth rule for the radiologist is to apply the appropriate differential diagnosis for the unique patient.
Young
How young is young? For the purposes of this chapter, we will consider any woman under 30 years to be young. The vast majority present with clinically or self-detected signs or symptoms; however, there is also a subset of the young population who are asymptomatic and present with screen-detected abnormalities. These are women with a greater than average lifetime risk of developing breast cancer who have initiated screening with mammography, ultrasound, and/or magnetic resonance imaging (MRI) before the age of 40. Please see Chapter 11 for details about screening high-risk women.
Young: Differential Considerations
The top differential diagnoses for young patients presenting with a focal symptom, such as a palpable abnormality or pain, include normal tissue, simple and complicated cysts, and fibroadenomas ( Box 19.1 ). Phyllodes tumors, papillomas, abscess or mastitis, tumoral pseudoangiomatous stromal hyperplasia (PASH), and breast cancer are also possible but less likely. In patients under 19, fibroadenomas account for 91% of the masses that are visible on ultrasound ( Fig. 19.1 ), and breast cancer is exceedingly rare.
Box 19.1
Young Women (<30 Years Old): Differential Considerations for Palpable Breast Lumps
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Normal breast tissue
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Cyst and fibrocystic changes
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Fibroadenoma
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Phyllodes tumor
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Pseudoangiomatous stromal hyperplasia
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Papilloma
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Breast cancer
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Other: hematoma, abscess, fat necrosis
Young: Imaging Management
For women under 30 with a focal breast sign or symptom, the first step in evaluation is a breast ultrasound targeted to the site of clinical concern. This choice of initial imaging test is guided by the incidence of cancer by decade, as the risk changes significantly over time ( Table 19.1 and Box 19.2 ). Whereas only 1 out of 1681 women in their 20 s will develop cancer before turning 30, 1 out of 232 women in their 30 s will develop breast cancer before turning 40, and 1 out of 69 women in their 40 s will develop breast cancer before turning 50.
Table 19.1
The Risk of Breast Cancer in Women Increases With Age
Ultrasound is the first imaging test recommended for women in their 20 s, because the likelihood of cancer is low and the sensitivity of mammography is lower in younger patients with relatively denser breast tissue.
| American College of Radiology (ACR) Appropriateness for Initial Evaluation of Palpable Lumps | |||
|---|---|---|---|
| Age | Risk of Malignancy in the Next Decade | Mammogram First | Ultrasound First |
| 20 | 1:1681 | 3 | 9 |
| 30 | 1:232 | 8 | 8 |
| 40 | 1:69 | 9 | 4 |
ACR Appropriateness Rating scale: 1–3 (usually not appropriate); 4– 6 (may be appropriate); 7– 9 (usually appropriate)
Box 19.2
Imaging Evaluation of Suspicious Symptoms in Young Women (<30 Years Old)
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Incidence of breast cancer is very low among young women at average risk.
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Sensitivity of mammography is limited by relatively denser tissue in younger women.
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Ultrasound is recommended as the initial imaging modality.
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Mammography is not contraindicated and may be considered when a suspicious ultrasound finding is identified.
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If performing mammography, get mediolateral oblique (MLO) and craniocaudal (CC) views of the contralateral asymptomatic breast to assess for asymmetries.
The dramatic increase in risk explains the recommendation to start screening at age 40, as well as the recommendation to use ultrasound as the first test in symptomatic women under 30 years. Mammography is not routinely performed in women under 30 due to the very low likelihood of breast cancer and the lower yield of mammography in younger patients with relatively denser breasts. There is also a desire to avoid unnecessary radiation, albeit a very low dose, in younger and more radiosensitive patients. However, while mammography is rarely used in women under 30, it is not contraindicated. If the sonographic findings are suspicious or do not explain the patient’s symptoms, mammography may be appropriate in some cases ( Box 19.3 ).
Box 19.3
Mammography in Women Younger Than 30 Years
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Not routinely performed, but not contraindicated.
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If ultrasound finding might represent fat necrosis or other benign calcification, mammography can help establish benignity.
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If ultrasound finding is highly concerning for malignancy, mammography can further characterize and assess extent of disease.
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If ultrasound is negative but clinical examination is highly suspicious, mammography should be considered for further evaluation.
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Bilateral mammogram should be performed in any women with proven cancer.
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Mammography can provide guidance for preoperative localization.
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Mammography can be used to assess response to therapy.
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Have a lower threshold to perform mammography in high-risk patients.
Young: Management of Breast Masses
The same imaging features, assessment structure, and classification system used to guide the management of breast masses in patients 40 years and older are used to guide the management of breast masses in younger patients. The lower incidence of breast cancer in this population means that the majority of breast masses will fall into the benign (BI-RADS 2) or probably benign (BI-RADS 3) categories.
Young: Probably Benign
Masses with imaging features meeting criteria for BI-RADS category 3 can be safely monitored with ultrasound and physical examination ( Fig. 19.2 and Box 19.4 ). Masses that remain stable for 2 to 3 years can be deemed benign and require no additional follow-up ( Box 19.5 ). Image-guided biopsy of a BI-RADS 3 mass may also be performed at any time if the patient prefers not to wait for the short-interval follow-up for example, if the patient is too anxious or if there is concern of not returning for follow-up.
Box 19.4
Differential Diagnosis of Probably Benign Masses (BI-RADS 3)
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Fibroadenoma (most common)
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Phyllodes tumor
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Tumoral pseudoangiomatous stromal hyperplasia (PASH)
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Complicated cyst
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Papilloma
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Rarely cancer: Beware this potential pitfall!
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Probably benign masses MUST be parallel, oval, and circumscribed.
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Any mass that is round (unless meeting criteria of a complicated cyst or simple cyst) is suspicious and may represent a rapidly growing high-grade invasive carcinoma.
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Box 19.5
Management of Probably Benign Breast Masses
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Safety of monitoring palpable lumps with BI-RADS 3 features with ultrasound and physical examination:
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If it is stable for 2–3 years, it can be assessed as benign and no additional follow-up required.
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If it changes/grows on physical examination, return for follow-up imaging immediately.
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When should percutaneous sampling be performed?
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The patient is too anxious to wait 6 months, requires a more urgent answer (e.g., planning to get pregnant, organ transplant candidate), or could be lost to follow-up.
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Volume or largest dimension of the mass increases by >20% in 6 months.
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Develops suspicious features at follow-up, no longer meeting probably benign criteria.
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Excisional biopsy should be performed if
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Percutaneous sampling demonstrates phyllodes tumor (or fibroepithelial lesion with features concerning for phyllodes tumor).
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Percutaneous sampling demonstrates fibroadenoma, but it grows by >20% at follow-up.
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Percutaneous sampling demonstrates fibroadenoma, but the patient desires excision, because the mass is large and symptomatic.
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If the physical examination of a BI-RADS 3 mass changes (e.g., grows) on palpation, the patient should return immediately for imaging reassessment. Although most of these masses are fibroadenomas, it is nearly impossible to distinguish them from phyllodes tumors using ultrasound alone. Tissue sampling should be recommended if the mass volume or largest dimension increases more than 20% in 6 months, as this increases the likelihood of phyllodes tumor (see Fig. 19.2 , Box 19.6 , and Table 19.2 ). If pathology demonstrates phyllodes tumor, complete excision with clear margins should be performed. Phyllodes tumors and fibroepithelial lesions are covered in Chapter 9 .
Box 19.6
Fibroadenoma Versus Phyllodes
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Both are fibroepithelial lesions and have similar imaging characteristics.
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Phyllodes tumor mean age at diagnosis: 40–49.
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Fibroadenoma mean age at diagnosis: 30–39.
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Phyllodes tumors are faster growing with potential for local recurrence.
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Approximately 25% of phyllodes tumors are malignant.
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Wide surgical excision is recommended for all phyllodes tumors.
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Fibroadenomas are benign and generally do not require excision.
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Most phyllodes tumors are very large at presentation.
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Larger size and rapid growth increase likelihood of phyllodes.
Table 19.2
Mass Size Measurements Corresponding to Fig. 19.2
The largest measurement and the volume of the mass increased by more than 20% in 6 months, upgrading the mass from a BI-RADS 3 (probably benign) to a BI-RADS 4 (suspicious) with a recommendation for biopsy.
| December | June | Difference | |
|---|---|---|---|
| Length | 1.7 cm | 2.4 cm | 41% |
| Width | 2.3 cm | 2.5 cm | 9% |
| Height | 1.4 cm | 1.5 cm | 7% |
| Volume | 2.7 cm 3 | 4.5 cm 3 | 67% |
Biopsy should be performed for masses with one or more suspicious imaging features ( Fig. 19.3 and Box 19.5 ). Extra vigilance is needed when evaluating solid masses that are circumscribed and homogeneously hypoechoic but are antiparallel, round, or have increased in size. Solid masses that are round can represent high-grade, fast-growing, invasive breast cancer. If any suspicious features are identified, ultrasound-guided biopsy should be recommended. Diagnostic mammography is not contraindicated and may be considered in a patient with a suspicious sonographic finding ( Table 19.3 ). The mammogram may show additional features that change the management (e.g., classic benign fat necrosis) of the patient or biopsy plan (e.g., segmental fine pleomorphic calcifications extending beyond the palpable mass) ( Fig. 19.4 ).
Table 19.3
Ultrasound characterisitcs of benign, probably benign, and suspicious masses
If the ultrasound finding has any feature that cannot be classified as BI-RADS 2 or 3, ultrasound-guided tissue sampling is warranted. It may be appropriate to either proceed directly to the biopsy or first perform a mammogram for further characterization of the suspicious sonographic finding.
| BI-RADS 2 | BI-RADS 3 | BI-RADS 4 | |
|---|---|---|---|
| Margin | Circumscribed | Circumscribed | Angular, indistinct, microlobulated, or spiculated |
| Shape | Oval | Oval | Round or irregular |
| Orientation | Parallel | Parallel | Not parallel |
| Echogenicity | Anechoic | Hypoechoic or isoechoic | Heterogeneous, hypoechoic, or complex cystic and solid |
| Posterior features | Enhancement | Enhancement or none | Shadowing |
| What is it? | Simple cyst | Probably fibroadenoma | Suspicious |
Young: Management of the Pathologic Nipple
Systemic hormonal influences explain the majority of bilateral milky spontaneous or expressed discharge in young women. Bilateral discharge does not require diagnostic imaging evaluation. However, when a young patient under 30 presents with suspicious nipple symptoms, including pathologic nipple discharge (i.e., unilateral, clear or bloody, and spontaneous), targeted ultrasound should be the initial modality used. Ultrasound should be directed to the subareolar region of the affected breast. Mammography may be complementary, especially for the detection of subtle calcifications. If initial imaging does not demonstrate a correlation with the patient’s symptoms, breast MRI or, less commonly, ductography could be considered. Symptom evaluation of the nipple is covered in depth in Chapter 14 .
Papilloma is uncommon in patients younger than 30, but can be considered when presenting with unilateral suspicious nipple discharge and one or more intraductal masses on ultrasound ( Fig. 19.5 ). Solitary and multiple papillomas are covered in greater detail in Chapter 9 . In contrast to papillomas, juvenile papillomatosis (also known as “Swiss cheese disease”) is a benign mass seen in patients younger than 30, which typically presents as a mobile palpable lump without discharge ( Box 19.7 ). Ultrasound most commonly shows a complex mass with multiple small cystic components.
Box 19.7
Juvenile Papillomatosis (also Known as “Swiss Cheese Disease”)
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Mean age of diagnosis is 23 years.
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Clinical presentation
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Palpable, mobile, discrete mass.
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Imaging appearance
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Mammogram rarely performed
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Ultrasound: variable cysts/masses.
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Pathology appearance
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Multiple small cysts within dense stroma (“Swiss cheese” appearance).
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Management
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Complete excision is usually performed.
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Cancer risk
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Juvenile papillomatosis is benign but may be a risk marker for familial breast cancer.
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Slightly increased lifetime risk of cancer suggested but not confirmed.
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Young: Special Considerations for Patients Under 18
Providing care to minors requires additional special consideration. In some cases, it may be appropriate to have a parent present for the examination and discussion. Physical and emotional maturity are highly variable in adolescence, and care should be taken to respect the individual preferences of the patient. Some young women may be embarrassed or reluctant to let a physician see her breast or to discuss their symptoms. Be mindful of the patient’s signals. In addition, a legal guardian’s consent is generally required for any biopsies performed.
Fortunately, breast cancer is extremely rare in the pediatric and adolescent population, comprising less than 0.1% of all breast cancers with an incidence of less than 1 per 100,000 among females under 19. Imaging and clinical follow-up is reasonable for the vast majority of children and adolescents presenting with breast masses, as nearly all in this population are benign, with fibroadenoma being the most common. While some patients or their parents may insist on biopsy or surgical excision in response to fear, a noninvasive approach is generally preferred, as it is less traumatic and reduces the risk of damage to the undeveloped or underdeveloped breast tissue. Damage to a normal developing breast bud can result in permanent partial or total failure of breast development.
Although exceedingly rare, there are case reports of pediatric breast carcinomas in the literature, most commonly secretory carcinoma, a slow-growing tumor with favorable prognosis. There are also rare benign lesions in children/adolescents that may require surgical consultation due to large size and progressive growth (e.g., phyllodes tumor, giant pseudoangiomatous stromal hyperplasia, and giant juvenile fibroadenoma). Lastly, there are developmental variants, such as a breast bud or asymmetric developing breast tissue in a child/adolescent or breast tissue in a neonate related to maternal hormones, that can present with a palpable finding. In these cases, imaging can sometimes be useful to establish benignity ( Box 19.8 ).
Box 19.8
Special Considerations for Patients Under 18
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It may be appropriate to have a parent or guardian in the room during the examination and/or to discuss results.
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Always ask the patient’s preference.
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Be sensitive to the embarrassment or self-consciousness of adolescence.
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Cancer is extremely rare.
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A noninvasive approach is appropriate in the vast majority of cases.
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Avoid damage to the undeveloped/underdeveloped breast.
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Do not biopsy or excise the breast bud, as this can result in permanent disruption of normal breast development.
Young: Summary
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Cancer is an unlikely diagnosis in this population.
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For diagnostic imaging evaluation of focal symptoms in patients under 30 years, start with ultrasound.
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If there are imaging features that deviate from benign or probably benign, biopsy should be recommended.
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Mammography is not contraindicated for women in their 20 s and may be appropriate after ultrasound in some scenarios.
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