Ebook Breast cancer - Diagnostic imaging and therapeutic guidance (1st Edition): Part 2

Imaging of Breast Lesions

8 Imaging of Breast Lesions
U. Fischer and S. Luftner-Nagel

8.1 Benign Findings

8.1.2 Inflamed Cysts

8.1.1 Cysts

The inflamed cyst is a simple cyst with inflamed—and thus
hyperemic—cyst walls.

The simple cyst is a fluid-filled cavity with a lining consisting of
an inner epithelial layer and an outer myoepithelial layer.
▶ Characteristics
● Incidence: very common.
● Peak age: all age groups; incidence decreases after menopause.
● Multifocality: frequent.
● Bilateral occurrence: frequent.
● Complications: none.
● Risk of malignancy: less than 1%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.
▶ Implications for work-up/treatment. None if symptom-free.
If there is pain, ultrasound-guided cyst aspiration, preferably by
fine needle, may be performed.

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▶ Shape. Round, oval.

▶ Characteristics
● Incidence: rare.
● Peak age: all age groups; incidence decreases after menopause.
● Multifocality: rare.
● Bilateral occurrence: rare.
● Complications: occasional pain.
● Risk of malignancy: less than 1%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.
▶ Implications for work-up/treatment. None if symptom-free.
If there is pain, ultrasound-guided cyst aspiration, preferably by
fine needle, may be performed.
▶ Shape. Round, oval.
▶ Margins. Predominantly circumscribed, occasionally slightly
indistinct.

▶ Margins. Circumscribed.
▶ Internal composition. Homogeneous fluid.
▶ Internal composition. Homogeneous fluid.
▶ Clinical findings. Small cysts normally have no correlative
clinical findings. In the case of larger cysts, a circumscribed,
firm-elastic mass may be palpable. Occasionally there is
tenderness.

▶ Clinical findings. Small cysts normally have no correlative
clinical findings. In the case of larger cysts, a circumscribed, firmelastic, occasionally tender mass may be palpable.
▶ Imaging
Sonography (▶ Fig. 8.2a): anechoic mass, cyst wall mildly thickened, possibly indistinct; posterior acoustic enhancement.

● Mammography (▶ Fig. 8.2b): mass with parenchyma-equivalent, homogeneous density; difficult or impossible to detect
within dense breast tissue structures; good visibility within the
lipomatous breast; occasional cyst wall calcifications.
● Breast MRI (▶ Fig. 8.2c): mass:
○ T1W precontrast image: hypointense.
○ T2W image: hyperintense.
○ After administration of contrast medium: cyst wall
enhancement.
●

▶ Imaging
● Sonography (▶ Fig. 8.1a): Anechoic mass; posterior acoustic enhancement; unambiguous sonographic finding.
● Mammography (▶ Fig. 8.1b): mass with parenchyma-equivalent, homogeneous density; difficult or impossible to detect
within dense breast tissue structures; good visibility within the
lipomatous breast; occasional cyst wall calcifications.
● Breast MRI (▶ Fig. 8.1c): mass:
○ T1W precontrast image: hypointense.
○ T2W image: hyperintense.
○ After administration of contrast medium: no enhancement.

Note
Note
Mammography cannot reliably distinguish between a cyst (fluidfilled) and a proliferative process (solid tissue).

▶ Differential diagnosis. Inflamed cyst, complex cyst, cyst with
intracystic proliferation, triple-negative carcinoma.

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When interpreting breast MRI, one should use the term “cyst wall

enhancement” rather than “rim enhancement,” because the term
“rim enhancement” is closely associated with malignancy.

▶ Differential diagnosis. Complex cyst, cyst with intracystic
proliferation, triple-negative carcinoma.


8.1 Benign Findings

a

b

8

c

Fig. 8.1 Simple cyst. (a) Ultrasound image. (b) Mammogram. (c) T2W breast MR image.

8.1.3 Complex Cysts
When bleeding occurs into a simple cyst, it is referred to as a
complex cyst (synonyms: hemorrhagic cyst, chocolate cyst). A
cyst filled with highly proteinaceous fluid also justifies use of the
term “complex cyst.”
▶ Characteristics
● Incidence: rare.
● Peak age: all age groups; incidence decreases after menopause.
● Multifocality: rare.
● Bilateral occurrence: rare.
● Complications: none.

● Risk of malignancy: less than 1%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.

▶ Implications for work-up/treatment. None if symptom-free.
If there is pain, ultrasound-guided cyst aspiration using a larger
gauge needle (10G) may be indicated.
▶ Shape. Round, oval.
▶ Margins. Circumscribed.
▶ Internal composition. Homogeneous to inhomogeneous due
to fresh blood (with sedimentation effect), old blood, protein.
▶ Clinical findings. Small lesions normally have no correlative
clinical findings. In the case of larger cysts, a circumscribed, firmelastic mass may be palpable. The lesions are rarely tender to
palpation.

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Imaging of Breast Lesions

a

b

8

c

Fig. 8.2 Inflamed cyst. (a) Ultrasound image. (b) Mammogram. (c) Contrast-enhanced breast MRI subtraction image.

▶ Imaging
● Sonography (▶ Fig. 8.3a): hypoechoic mass; minor posterior
acoustic enhancement (protein), moderate acoustic enhancement to acoustic extinction (old blood).
● Mammography (▶ Fig. 8.3b): mass with parenchyma-equivalent, homogeneous density; difficult or impossible to detect
within dense breast tissue structures; good visibility within the
lipomatous breast.
● Breast MRI (▶ Fig. 8.3c): mass:
○ T1W precontrast image: isointense (protein) to hypointense
(old blood); sedimentation may be visible.
○ T2W image: isointense (protein) to hypointense (old blood);
sedimentation may be visible.
○ After administration of contrast medium: no to slight cyst
wall enhancement.

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Note
When there is uncertainty in the differential diagnosis of a complex breast cyst, percutaneous biopsy should be undertaken.

▶ Differential diagnosis. Inflamed cyst, cyst with intracystic
proliferation, triple-negative carcinoma, carcinoma with central
degeneration.

8.1.4 Myxoid Fibroadenoma
Fibroadenomas are benign, mixed fibroepithelial tumors. In
younger women, they usually present with a high epithelial content (myxoid fibroadenoma).


8.1 Benign Findings

a

b

8

c

Fig. 8.3 Hemorrhagic cyst. (a) Ultrasound image. (b) Mammogram. (c) T2W breast MR image.

▶ Characteristics
● Incidence: frequent.
● Peak age: 18 to 50 years.
● Multifocality: frequent.
● Bilateral occurrence: frequent.
● Complications: usually none. The juvenile giant fibroadenoma is
an exception due to its massive size (diameter up to 12–15 cm).
● Risk of malignancy: 0%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.

should be histologically confirmed via percutaneous, preferably
ultrasound-guided, core needle biopsy. Giant fibroadenomas
should be surgically excised.

▶ Implications for work-up/treatment. For smaller lesions in
younger women (up to 30 years of age), no treatment is required.
For smaller lesions in women aged 30 years and above, diagnosis

▶ Clinical findings. Small cysts normally have no correlative

clinical findings. In the case of larger myxoid fibroadenomas, circumscribed lumps may be palpable.

▶ Shape. Lobular, oval.
▶ Margins. Circumscribed.
▶ Internal composition. Homogeneous, proliferative tissue.

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Imaging of Breast Lesions
▶ Imaging
● Sonography (▶ Fig. 8.4a): homogeneous, isoechoic mass; longitudinal axis parallel to the skin; mild elasticity; mild posterior
acoustic enhancement.
● Mammography (▶ Fig. 8.4b): mass with parenchyma-equivalent, homogeneous density; difficult or impossible to detect
within dense breast tissue structures; good visibility within the
lipomatous breast; rarely displays endotumoral
microcalcifications.
● Breast MRI (▶ Fig. 8.4c): focus, mass:
○ T1W precontrast image: hypointense.
○ T2W image: hyperintense; may display endotumoral hypointense septations with increasing fibrosis.
○ After administration of contrast medium: strong homogeneous enhancement; may display nonenhancing endotumoral
septations with increasing fibrosis (dark septations).

Note
Myxoid fibroadenomas are the most common tumors in young
women.

▶ Differential diagnosis. Adenoma, papilloma, phyllodes tumor,
invasive carcinoma, intramammary metastasis.

8.1.5 Fibrotic Fibroadenoma
Fibroadenomas are benign, mixed fibroepithelial tumors. With
increasing age, the fibrous component increasingly predominates
(fibrotic fibroadenoma; synonyms: hyaline fibroadenoma, regressive fibroadenoma).

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a

b

c

Fig. 8.4 Myxoid fibroadenoma. Fibroadenoma with high water content. (a) Ultrasound image. (b) Mammogram. (c) Contrast-enhanced breast MRI
subtraction image.

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8.1 Benign Findings
▶ Characteristics
● Incidence: frequent.
● Peak age: 40 to 80 years.
● Multifocality: frequent.
● Bilateral occurrence: frequent.
● Complications: none.
● Risk of malignancy: 0%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.
▶ Implications for work-up/treatment. When there is uncertainty in the differential diagnosis, percutaneous, preferably

ultrasound-guided, core needle biopsy should be undertaken.
▶ Shape. Lobular, oval.

▶ Margins. Circumscribed.
▶ Internal composition. Inhomogeneous to homogeneous proliferative tissue.
▶ Clinical findings. Small lesions normally have no correlative
clinical findings. In the case of a larger fibrotic fibroadenoma, a
circumscribed, rather firm mass may be palpable.
▶ Imaging
● Sonography (▶ Fig. 8.5a): inhomogeneous or homogeneous,
hypoechoic to isoechoic mass; longitudinal axis parallel to the
skin; no elasticity; intermediate posterior echo pattern to
acoustic extinction (acoustic extinction is particularly seen in
the case of endotumoral macrocalcifications).

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a

b

c

Fig. 8.5 Fibrous fibroadenoma. Fibroadenoma with regressive changes. (a) Ultrasound image. (b) Mammogram. (c) T1W precontrast breast MR
image.

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Imaging of Breast Lesions

●

●

Mammography (▶ Fig. 8.5b): mass with parenchyma-equivalent, homogeneous density; difficult or impossible to detect
within dense breast tissue structures; good visibility within the
lipomatous breast; frequently displays endotumoral macrocalcifications (popcornlike).
Breast MRI (▶ Fig. 8.5c): focus, mass:
○ T1W precontrast image: isointense; endotumoral signal loss
in the case of macrocalcifications.
○ T2W image: isointense; endotumoral signal loss in the case of
macrocalcifications.
○ After administration of contrast medium: minor or no
enhancement.

●

●

Note
Adenoma of the nipple represents a variant form of adenoma. It
grows in the terminal portion of the nipple and is preferably
treated with surgical excision (differential diagnosis: eczema,
Paget’s disease).

Note
Popcornlike endotumoral macrocalcifications on mammography
are pathognomonic for a fibrotic fibroadenoma.

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Mammography (▶ Fig. 8.6b): mass with parenchyma-equivalent, homogeneous density; difficult or impossible to detect
within dense breast tissue structures; good visibility within the
lipomatous breast; may rarely display endotumoral
microcalcifications.
Breast MRI (▶ Fig. 8.6c): focus, mass:
○ T1W precontrast image: hypointense.
○ T2W image: hyperintense.
○ After administration of contrast medium: moderate to strong
homogeneous enhancement.

▶ Differential diagnosis. Adenoma, papilloma, phyllodes tumor,
invasive carcinoma, intramammary metastasis.

▶ Differential diagnosis. Fibroadenoma, papilloma, phyllodes
tumor, invasive carcinoma.

8.1.6 Adenoma

8.1.7 Hamartoma

The adenoma, as opposed to the fibroadenoma, exhibits only a
very minor stromal component. It is a circumscribed tumor with
tubular structures and a surrounding pseudocapsule.

The hamartoma (synonym: fibroadenolipoma, lipofibroadenoma,
“breast within the breast”) is a circumscribed mixed tumor with
organoid composition and pseudocapsular margins.

▶ Characteristics

● Incidence: rare.
● Peak age: usually in younger women up to 50 years of age.
● Multifocality: rare.
● Bilateral occurrence: rare.
● Complications: none.
● Risk of malignancy: 0%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.
▶ Implications for work-up/treatment. For smaller lesions in
younger women (up to 30 years of age), no treatment is required.
For smaller lesions in women aged 30 years and above, confirmation of the diagnosis via percutaneous, preferably ultrasoundguided, core needle biopsy should be undertaken.

▶ Characteristics
Incidence: rare.
● Peak age: all age groups.
● Multifocality: rare.
● Bilateral occurrence: rare.
● Complications: none.
● Risk of malignancy: 0%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.
●

▶ Implications for work-up/treatment: None. When there is
uncertainty in the differential diagnosis, percutaneous, preferably
ultrasound-guided, core needle biopsy, should be undertaken
and should include portions of the pseudocapsule.
▶ Shape. Round, oval, lobular.

▶ Shape. Round, oval, lobular.

▶ Margins. Circumscribed; the lesion displays a pseudocapsule.
▶ Margins. Circumscribed.
▶ Internal composition. Usually homogeneous proliferative tissue; may rarely display lipomatous inclusions.
▶ Clinical findings. Small lesions normally have no correlative
clinical findings. In the case of a larger adenoma, a circumscribed,
rather soft mass may be palpable.
▶ Imaging
Sonography (▶ Fig. 8.6a): homogeneous, isoechoic mass; longitudinal axis parallel to the skin; good elasticity; mild posterior
acoustic enhancement.

●

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▶ Internal composition. Inhomogeneous parenchyma-equivalent tissue (fat, parenchyma, vessels).
▶ Clinical findings. Small lesions normally have no correlative
clinical findings. In the case of a larger hamartoma, a circumscribed mass may be palpable. The consistency is dependent
upon the composition.
▶ Imaging
Sonography (▶ Fig. 8.7a): inhomogeneous mass with echogenicity depending upon the composition (fat and parenchymal
components).

●


8.1 Benign Findings

a

b

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c

Fig. 8.6 Adenoma. (a) Ultrasound image. (b) Mammogram. (c) Contrast-enhanced breast MRI subtraction image.

●

●

Mammography (▶ Fig. 8.7b): mass with hyperdense to hypodense tumor areas depending upon the endotumoral composition; impression of a “breast within the breast” (termed so by
the pathologist Thomas Bässler); very rarely displays endotumoral microcalcifications.
Breast MRI (▶ Fig. 8.7c): mass:
○ T1W precontrast image: mixed presentation (hypointense to
hyperintense), depending upon composition.
○ T2W image: mixed presentation (hypointense to hyperintense), depending upon composition.
○ After administration of contrast medium: usually displays
inhomogeneous enhancement of the parenchymal tumor
areas.

Note
The composition and perfusion pattern of a hamartoma can be
differentiated distinctly from the characteristics of the normal
glandular tissue.

▶ Differential diagnosis. Phyllodes tumor.

8.1.8 Lipoma
The lipoma (synonym: adipose tumor) is an encapsulated tumor

that contains exclusively mature adipose cells.

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Imaging of Breast Lesions

a

b

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c

Fig. 8.7 Hamartoma. Mixed tumor. (a) Ultrasound image. (b) Mammogram. (c) T1W precontrast breast MR image.

▶ Characteristics
● Incidence: rare.
● Peak age: all age groups.
● Multifocality: rare.
● Bilateral occurrence: rare.
● Complications: none.
● Risk of malignancy: 0%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.
▶ Implications for work-up/treatment. None.
▶ Shape. Oval.
▶ Margins. Circumscribed, displays a delicate capsule.

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▶ Internal composition. Homogeneous fat.
▶ Clinical findings. Small lesions normally have no correlative
clinical findings. In the case of a larger lipoma, a circumscribed,
soft, cushionlike mass may be palpable.
▶ Imaging
Sonography (▶ Fig. 8.8a): hyperechoic mass (due to the arrangement of the adipose cells, echogenicity is frequently higher than
that of subcutaneous or intramammary adipose tissue).
● Mammography (▶ Fig. 8.8b): hypodense (fat-equivalent) mass
with delicate surrounding capsule; no associated
microcalcifications.
● Breast MRI (▶ Fig. 8.8c): mass:
○ T1W precontrast image: hyperintense.
●


8.1 Benign Findings
T2W image: hyperintense; hypointense in T2W fatsuppressed.
○ After administration of contrast medium: no enhancement.
○

Note
Liposarcoma does not develop from a breast lipoma.

▶ Differential diagnosis. Free intramammary adipose tissue.

8.1.9 Mammary Fibrosis
Mammary fibrosis is a regional or diffuse proliferation of the
stroma with obliteration of the lactiferous ducts.

a

▶ Characteristics
● Incidence: frequent.
● Peak age: all age groups.
● Multifocality: frequent.
● Bilateral occurrence: frequent.
● Complications: none.
● Risk of malignancy: not increased.
● Prognosis: excellent.
● Histological classification after biopsy: B2.

8

▶ Implications for work-up/treatment. None. When there is
uncertainty in the differential diagnosis, percutaneous biopsy
should be undertaken.
▶ Shape, distribution. Irregular, regional.
▶ Margins. Indistinct.
▶ Internal composition. Inhomogeneous proliferative tissue.
▶ Clinical findings. Small lesions normally have no correlative
clinical findings. An areas of extensive fibrosis may be palpable as
a firm mass.
b

▶ Imaging
● Sonography (▶ Fig. 8.9a): nonspecific inhomogeneous, hypoechogenic area, frequently occult.
● Mammography (▶ Fig. 8.9b): inhomogeneous, hyperdense area,
occasionally presenting as a focal asymmetry or density; nonspecific; rarely associated with microcalcifications.

● Breast MRI (▶ Fig. 8.9c): non-space-occupying lesion (nonmasslike lesion):
○ T1W precontrast image: intermediary signal, nonspecific.
○ T2W image: intermediary signal, nonspecific.
○ After administration of contrast medium: mild to strong enhancement, nonspecific.

Note
c

Fig. 8.8 Lipoma. Adipose tumor. (a) Ultrasound image. (b) Mammogram. (c) T1W precontrast breast MR image.

Mammary fibrosis is usually visualized as ambiguous microcalcifications on the mammogram or as a nonmasslike area of
increased enhancement in the MRI.

▶ Differential diagnosis. Adenosis, DCIS, ILC.

119


Imaging of Breast Lesions

8.1.10 Adenosis of the Breast
Adenosis (synonym: adenosis mammae) is a clustered proliferation
of the small ductal segments and terminal ducts. Histopathology
differentiates the following types: sclerosing adenosis, microcystic
adenosis (blunt-duct adenosis), and the less common microglandular adenosis and the radial scar (see Chapter 8.2.2).

a

▶ Characteristics
● Incidence: frequent.

● Peak age: all age groups.
● Multifocality: frequent.
● Bilateral occurrence: frequent.
● Complications: none.
● Risk of malignancy: not increased.
● Prognosis: excellent.
● Histological classification after biopsy: B2.
▶ Implications for work-up/treatment. None. When there is
uncertainty in the differential diagnosis, percutaneous biopsy
should be undertaken.

8

▶ Shape, distribution. Irregular; regional or multiregional.
▶ Margins. Indistinct.
▶ Internal composition. Inhomogeneous proliferative tissue.
▶ Clinical findings. Small lesions normally have no correlative
clinical findings. A larger area of adenosis may be palpable as an
area of increased firmness.

b

▶ Imaging
● Sonography (▶ Fig. 8.10a): nonspecific, inhomogeneous, hypoechogenic area, frequently occult.
● Mammography (▶ Fig. 8.10b): inhomogeneous, hyperdense area,
occasionally presenting as a focal asymmetry or density; nonspecific; frequently associated with microcalcifications (monomorphic, round); in the case of blunt-duct adenosis, often
associated with amorphous calcifications in lobular distribution.
● Breast MRI (▶ Fig. 8.10c): non-space-occupying lesion (nonmasslike lesion):
○ T1W precontrast image: intermediary signal, nonspecific.
○ T2W image: intermediary signal, nonspecific.

○ After administration of contrast medium: often displays
strong enhancement, nonspecific.

Note
Circumscribed adenosis is the most common cause of falsepositive findings on breast MRI because it exhibits an irregular
shape and is often associated with increased perfusion.

c

Fig. 8.9 Mammary fibrosis. (a) Ultrasound image. (b) Mammogram.
(c) Contrast-enhanced breast MRI subtraction image.

120

▶ Differential diagnosis. Mammary fibrosis, DCIS, ILC.


8.1 Benign Findings

a

b

8

c

Fig. 8.10 Adenosis. Sclerosing adenosis. (a) Ultrasound image. (b) Mammogram. (c) Nodular adenosis in the T1W precontrast breast MR image.

8.1.11 Fibrocystic Condition of the

Breast
Morphological components of the fibrocystic condition of the
breast (also referred to as fibrocystic mastopathy, fibrocystic
breasts, fibrocystic disease of the breast, fibrocystic changes) are:
micro- and macrocysts in varying degrees; hyperplasia of the
lobules; epithelial hyperplasia of the lactiferous ducts and acini;
and stromal fibrosis.

●
●
●

Risk of malignancy: not increased.
Prognosis: excellent.
Histological classification after biopsy: B1.

▶ Implications for work-up/treatment. None. When there is
uncertainty in the differential diagnosis, percutaneous biopsy
should be undertaken.
▶ Shape, distribution. Irregular, diffuse, rarely regional.
▶ Margins. Indistinct.

▶ Characteristics
● Incidence: frequent.
● Peak age: all age groups.
● Multifocality: frequent.
● Bilateral occurrence: obligatory.
● Complications: none.

▶ Internal composition. Inhomogeneous proliferative tissue + cysts.

▶ Clinical findings. Unremarkable to mild or moderately
increased firmness.

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Imaging of Breast Lesions
▶ Imaging
● Sonography (▶ Fig. 8.11a): Generally hyperechogenic breast tissue; hypoechoic tubular changes (ectatic milk ducts); anechoic
lesions with posterior acoustic enhancement (cysts); often
bilaterally symmetric.
● Mammography (▶ Fig. 8.11b): circumscribed or diffuse areas of
hyperdensity; frequently associated with micro- and macrocalcifications; often bilaterally symmetric.
● Breast MRI (▶ Fig. 8.11c): non-space-occupying lesion (nonmasslike lesion):
○ T1W precontrast image: hypointense lesions (cysts); otherwise nonspecific.
○ T2W image: hyperintense lesions (cysts); otherwise
nonspecific.
○ After administration of contrast medium: no/slight/strong enhancement, sparing the cystic lesions; nonspecific.

Note
In general, the term, “mastopathy,” should be avoided and
regarded as archaic. Currently it is only used in association with
fibrocystic changes.

▶ Differential diagnosis. Fibrosis, adenosis, any diffuse tumor
manifestation.

8.1.12 Adenomyoepithelioma
An adenomyoepithelioma is a circumscribed nodule consisting of
a proliferation of myoepithelial cells.

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a

b

c

Fig. 8.11 Fibrocystic condition of the breast. (a) Ultrasound image. (b) Mammogram. (c) T2W breast MR image.

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8.1 Benign Findings
▶ Characteristics
● Incidence: very rare.
● Peak age: all age groups.
● Multifocality: very rare.
● Bilateral occurrence: very rare.
● Complications: none.
● Risk of malignancy: 0%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.
▶ Implications for work-up/treatment. None. When there is
uncertainty in the differential diagnosis, percutaneous biopsy
should be undertaken.
▶ Shape. Round, oval.
▶ Margins. Circumscribed or indistinct.

▶ Clinical findings. Small lesions normally have no correlative
clinical findings. Larger lesions may present as circumscribed,
usually firm nodules.
▶ Imaging
Sonography (▶ Fig. 8.12a): hypoechogenic mass, nonspecific.
● Mammography (▶ Fig. 8.12b): hyperdense mass, nonspecific.
● Breast MRI (▶ Fig. 8.12c): focus, mass:
○ T1W precontrast image: parenchyma-equivalent, nonspecific.
○ T2W image: parenchyma-equivalent, nonspecific.
○ After administration of contrast medium: moderate to strong
enhancement; may display postinitial washout.
●

Note
Adenomyoepitheliomas do not exhibit any specific imaging characteristics. Due to their increased vascularity, they are frequently
false-positive findings in MRI.

▶ Internal composition. Inhomogeneous proliferative tissue.

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a

b

c

Fig. 8.12 Adenoepithelioma. (a) Ultrasound image. (b) Mammogram. (c) Contrast-enhanced breast MRI subtraction image.

123

Imaging of Breast Lesions
▶ Differential diagnosis. Fibroadenoma, papilloma, phyllodes
tumor, carcinoma of the breast.

8.1.13 Acute Nonpuerperal Mastitis
Acute nonpuerperal mastitis of the breast (synonym: acute
inflammation of the breast) is a predominantly interstitial, but
occasionally also intraductal, inflammation of the parenchyma
outside the lactation period.
▶ Characteristics
● Incidence: rare.
● Peak age: all age groups.
● Multifocality: may extend over the entire breast.
● Bilateral occurrence: very rare.
● Complications: abscess formation; development of fistulas.
● Risk of malignancy: 0%.
● Prognosis: good.
● Histological classification after biopsy: B2.
▶ Implications for work-up/treatment. Primary treatment of
the inflammation: immobilization, cooling, administration of

8

antibiotics. If the symptoms do not completely regress in 7 to 10
days, confirm the diagnosis with a percutaneous biopsy or open
representative excision.
▶ Shape, distribution. Irregular, frequently segmental or diffuse
(entire breast).

▶ Margins. Indistinct.
▶ Internal composition. Inhomogeneous proliferative, edematous tissue.
▶ Clinical findings. Inflammation triad: warmth to the touch,
redness, pain. Possible swelling, skin thickening, lymphadenitis,
and fever. May be associated with increased laboratory inflammatory markers.
▶ Imaging
● Sonography (▶ Fig. 8.13a): Hyperechogenicity of the parenchyma and subcutaneous space (edematous imbibitioncompare with the contralateral breast), skin thickening,
locoregional lymphadenitis.

Fig. 8.13 Acute nonpuerperal
mastitis. (a) Ultrasound image.
(b) Mammogram. (c) Contrastenhanced breast MRI subtraction
image.

a

c

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b


8.1 Benign Findings
●

●

Mammography (▶ Fig. 8.13b): Hyperdensity and decreased
transparency (tissue structures with a “washed-out appearance”—compare with the contralateral breast!), skin thickening,

locoregional lymphadenitis.
Breast MRI (▶ Fig. 8.13c): non-space-occupying lesion (nonmasslike lesion):
○ T1W precontrast image: no specific intramammary changes;
skin thickening; locoregional lymphadenitis.
○ T2W image: hyperintensity of the affected parenchymal
areas; skin thickening; locoregional lymphadenitis.
○ After administration of contrast medium: increased enhancement of the thickened skin; often greatly increased perfusion
of the inflamed parenchymal areas.

Note
It is frequently difficult or impossible to distinguish between nonpuerperal mastitis and inflammatory breast cancer on a clinical or
imaging basis.

●

●

Mammography (▶ Fig. 8.14b): hyperdensity; trabecular thickening; retroareolar ductal ectasia; in its final stage radially
arranged, lancetlike calcifications are classic (plasma cell
mastitis).
Breast MRI (▶ Fig. 8.14c): non-space-occupying lesion (nonmasslike lesion):
○ T1W precontrast image: hypointense, nonspecific.
○ T2W image: hyperintense, nonspecific; occasionally ectatic
milk ducts.
○ After administration of contrast medium: mild to strong enhancement, regional or segmental.

Note
The chronic inflammation associated with chronic nonpuerperal
mastitis is not typically associated with any symptoms.

▶ Differential diagnosis. Adenosis, fibrosis, inflammatory carcinoma of the breast.

▶ Differential diagnosis. Inflammatory breast cancer.

8.1.15 Intramammary Lymph Nodes

8.1.14 Chronic Nonpuerperal Mastitis

Intramammary lymph nodes appear morphologically identical to
axillary lymph nodes. It is merely the position within the glandular structures of the breast that defines them.

Chronic nonpuerperal mastitis (synonym: chronic abacterial
inflammation of the breast) is a chronic, abacterial, inflammatory
process that occurs in and around the terminal ducts and lobules
of the breast. Histopathology differentiates the following 3 forms:
galactophoritis, granulomatous mastitis, and lobular mastitis.
Plasma cell mastitis is the final stage of circumductal mastitis.
▶ Characteristics
● Incidence: rare.
● Peak age: higher age groups.
● Multifocality: very rare.
● Bilateral occurrence: very rare.
● Complications: none.
● Risk of malignancy: 0%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.

8

▶ Characteristics

● Incidence: rare; more common following extensive breast
surgery.
● Peak age: all age groups.
● Multifocality: rare.
● Bilateral occurrence: rare.
● Complications: none.
● Risk of malignancy: 0%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.
▶ Implications for work-up/treatment. None. When there is
uncertainty in the differential diagnosis, percutaneous biopsy
should be undertaken.

▶ Implications for work-up/treatment. None. When there is
uncertainty in the differential diagnosis, percutaneous biopsy
should be undertaken.

▶ Shape. Oval (kidney-shaped) hilum.

▶ Shape, distribution. Irregular, frequently ductal or segmental.

▶ Internal composition. Proliferative tissue with lipomatous
vascular pedicle.

▶ Margins. Circumscribed.

▶ Margins. Indistinct .
▶ Clinical findings. Unremarkable.
▶ Internal composition. Inhomogeneous proliferative tissue.
▶ Clinical findings. Small lesions normally have no correlative

clinical findings. Rarely associated with pain, nipple discharge, or
retraction of the nipple.
▶ Imaging
● Sonography (▶ Fig. 8.14a): hypoechogenic tissue; hypoechoic
tubular changes (mammary duct ectasia); nonspecific.

▶ Imaging
● Sonography (▶ Fig. 8.15a): hypoechogenic mass, hyperechoic
hilum, pathognomonic.
● Mammography (▶ Fig. 8.15b): hyperdense mass with hypodense (fat-equivalent) hilum, pathognomonic.
● Breast MRI (▶ Fig. 8.15c): mass:
○ T1W precontrast image: hypointense, hyperintense hilum,
pathognomonic.

125


Imaging of Breast Lesions

a

b

8

c

Fig. 8.14 Chronic mastitis. (a) Ultrasound image of chronic-segmental inflammation. (b) Plasma cell mastitis on mammography. (c) Chronic,
segmental inflammation in the contrast-enhanced breast MRI subtraction image.

T2W: hyperintense, hilum hyperintense (T2W) or hypointense (T2W with fat saturation).
○ After administration of contrast medium: no enhancement to
strong enhancement.
○

Note
Imaging cannot reliably differentiate between lymphadenitis and
the presence of metastatic disease within a lymph node.

▶ Differential diagnosis. In the case of typical lymph node
morphology, there is no differential diagnosis.

126

8.1.16 Pseudoangiomatous Stromal
Hyperplasia
Pseudoangiomatous stromal hyperplasia (PASH) is a benign intramammary lesion characterized by concentrically oriented, pseudoangiomatous cavities lined with CD34-positive cells.
▶ Characteristics
● Incidence: rare.
● Peak age: all age groups.
● Multifocality: rare.
● Bilateral occurrence: rare.
● Complications: none.
● Risk of malignancy: 0%.


8.1 Benign Findings

a

8
b

c

Fig. 8.15 Intramammary lymph nodes. Lymph nodes located within the parenchyma. (a) Ultrasound image. (b) Mammogram. (c) T1W precontrast
breast MR image.

●
●

Prognosis: excellent.
Histological classification after biopsy: B2.

▶ Implications for work-up/treatment. None. When there is
uncertainty in the differential diagnosis, percutaneous biopsy
should be undertaken.
▶ Shape. Round to irregular.
▶ Margins. Indistinct.
▶ Internal composition. Inhomogeneous angiomatous tissue.
▶ Clinical findings. Typically, there are no correlative clinical
findings, even with larger lesions.

▶ Imaging
● Sonography (▶ Fig. 8.16a): hypoechogenic area; rarely displays
positive color coding in the color-coded Doppler sonography;
nonspecific.
● Mammography (▶ Fig. 8.16b): hyperdensity, nonspecific.
● Breast MRI (▶ Fig. 8.16c): focus, mass, non-space-occupying
lesion (nonmasslike lesion):

○ T1W precontrast image: hypointense, nonspecific.
○ T2W: hyperintense, nonspecific.
○ After administration of contrast medium: obligatory moderate to strong enhancement, unspecific time to signal intensity
curve.

Note
PASH is associated with increased contrast enhancement on MRI.

127


Imaging of Breast Lesions

a

b

8

c

Fig. 8.16 Pseudoangiomatous stromal hyperplasia (PASH). (a) Ultrasound image. (b) Mammogram. (c) Contrast-enhanced breast MRI subtraction
image.

▶ Differential diagnosis. Fibrosis, adenosis, hemangioma, mastitis, DCIS, ILC.

●
●
●

8.1.17 Seroma
The designation of “seroma” describes an accumulation of wound
secretions (e.g., after a surgical procedure).
▶ Characteristics
● Incidence: common following surgical procedures.
● Peak age: all age groups.
● Multifocality: possible in the case of ipsilateral, multifocal interventional procedures.
● Bilateral occurrence: possible in the case of bilateral interventional procedures.
● Complications: none.

128

Risk of malignancy: 0%.
Prognosis: excellent.
Histological classification after biopsy: B2.

▶ Implications for work-up/treatment. None if symptom-free.
When symptoms occur, drainage may be indicated.
▶ Shape. Oval.
▶ Margins. Circumscribed.
▶ Internal composition. Homogeneous fluid.
▶ Clinical findings. Small seromas normally have no correlative
clinical findings. In the case of larger lesions, a mass may be palpable. Occasionally tenderness or pain is present.


8.1 Benign Findings
▶ Imaging
● Sonography (▶ Fig. 8.17a): hypoechogenic mass; occasionally
displays villiform echo alterations within the fluid.
● Mammography (▶ Fig. 8.17b): hyperdensity, nonspecific.

● Breast MRI (▶ Fig. 8.17c): mass:

T1W precontrast image: hypointense.
T2W: hyperintense.
○ After administration of contrast medium: usually no enhancement; rare contrast enhancement of the seroma walls.
○
○

Note
On ultrasound, seromas may display solid tissue structures within
the fluid interior.

▶ Differential diagnosis. Cyst, complex cyst, cyst with intracystic proliferation, bleeding, abscess.

8.1.18 Hematoma
A hematoma is a mass of, usually clotted, blood resulting from an
intramammary hemorrhage, typically after an interventional
procedure or surgery, and rarely after trauma.

a

▶ Characteristics
● Incidence: per se, very rare; common after biopsy.
● Peak age: all age groups.
● Multifocality: following ipsilateral biopsies in various locations.
● Bilateral occurrence: following bilateral biopsies.
● Complications: infection, abscess.
● Risk of malignancy: 0%.
● Prognosis: good.
● Histological classification after biopsy: B2.

8

▶ Implications for work-up/treatment. None if symptom-free.
When symptoms occur, fluid drainage if indicated (large-caliber
needle!).
▶ Shape. Round, oval; irregular in the case of diffuse bleeding.
▶ Margins. Circumscribed; indistinct in the case of diffuse
bleeding.
▶ Internal composition. Inhomogeneous blood components.
▶ Clinical findings. Small hematomas normally have no correlative clinical findings. A mass may be palpable in the case of larger
hematomas. Occasionally there may be tenderness or pain.
Cutaneous discoloration may develop subsequently from black/
purple, to red, blue, green, and yellow.
b

c

Fig. 8.17 Seroma. Postoperative seroma. (a) Ultrasound image.
(b) Mammogram. (c) T2W breast MR image.

▶ Imaging
● Sonography (▶ Fig. 8.18a): hypoechogenic mass; occasionally
displaying inhomogeneous internal echotexture and/or sedimentation effect.
● Mammography (▶ Fig. 8.18b): hyperdense mass; nonspecific.
● Breast MRI (▶ Fig. 8.18c): mass:
○ T1W precontrast image: dependent on the age of the hematoma may be hyperintense (fresh hematoma), hyperintense
ring (subacute hematoma), or anechoic due to susceptibility
artifacts (old, residual hematoma).
○ T2W: hypointense (fresh hematoma); hypointense ring (old

hematoma).

129


Imaging of Breast Lesions
○

After administration of contrast medium: mild reactive enhancement in the periphery of the hematoma.

Note
The MRI signal behavior of hematomas changes depending on
their age.

▶ Differential diagnosis. Seroma, abscess.

8.1.19 Fat Necrosis (Oil Cyst)
a

Fat necrosis (synonyms: liponecrosis microcystica calcificata) is a
circumscribed area of dead adipose tissue associated with leukocytic and histiocytic infiltrates. The transformation into scar tissue
is usually complete in a matter of weeks. Persistence of liquefied
adipose tissue results in the formation of so-called “oil cysts.”
▶ Characteristics
Incidence: common after surgery, rarely traumatic.
● Peak age: all age groups.
● Multifocality: following surgery in various ipsilateral locations.
● Bilateral occurrence: following bilateral surgery.
● Complications: none.
● Risk of malignancy: 0%.

● Prognosis: excellent.
● Histological classification after biopsy: B2.
●

8

▶ Implications for work-up/treatment. None. When there is
uncertainty in the differential diagnosis, (e.g. fat necrosis versus
recurrence after surgery for a carcinoma), a percutaneous biopsy
should be undertaken.
b

▶ Shape. Round to irregular.
▶ Margins. Circumscribed to indistinct.
▶ Internal composition. Adipose tissue.
▶ Clinical findings. Small lesions normally have no correlative
clinical findings. In the case of larger lesions, a firm mass may be
palpable. Occasionally tenderness or pain is present.

c

Fig. 8.18 Intramammary hematoma. (a) Ultrasound image of a
circumscribed hematoma following vacuum-assisted biopsy. (b) Mammogram of circumscribed hematoma following vacuum-assisted biopsy.
(c) Older hematoma in the T1W precontrast breast MR image.

130

▶ Imaging
● Sonography (▶ Fig. 8.19a): hypoechogenic mass, often nonspecific, often occult in early stages.
● Mammography (▶ Fig. 8.19b): hyperdensity, frequently nonspecific (fresh fat necrosis); mass with fat-equivalent density, macrocalcification of the oil cyst wall is highly specific (old fat

necrosis).
● Breast MRI (▶ Fig. 8.19c): focus, mass, non-space-occupying
lesion (nonmasslike lesion):
○ T1W precontrast image: isointense, nonspecific (fresh fat
necrosis); later fat-equivalent/hyperintense (highly specific
for an oil cyst).
○ T2W: hyperintense, nonspecific (fresh fat necrosis); later
hypointense in the fat-suppression measurement, highly
specific (oil cyst).


8.1 Benign Findings
○

After administration of contrast medium: moderate to strong
enhancement (fresh fat necrosis); later, mild reactive enhancement, if any.

Note
Fat necrosis can be regarded as “fresh” within the first 6 months
after surgery.

▶ Differential diagnosis. Inflammation, breast carcinoma or
tumor recurrence (in the case of fresh fat necrosis).
a

8.1.20 Abscess
A breast abscess is a localized intramammary collection of pus in
a cavity formed by an inflammatory degeneration of tissue.
Abscesses may occur after interventional or surgical procedures,
or in association with mastitis.

▶ Characteristics
● Incidence: very rare.
● Peak age: all age groups.
● Multifocality: very rare.
● Bilateral occurrence: very rare.
● Complications: fistula formation, perforation, sepsis.
● Risk of malignancy: 0%.
● Prognosis: good.
● Histological classification after biopsy: B2.

8

▶ Implications for work-up/treatment. None if symptom-free.
When there is uncertainty in the differential diagnosis, percutaneous biopsy should be undertaken.
b

▶ Shape. Round.
▶ Margins. Indistinct.
▶ Internal composition. Pus, homogeneous.
▶ Clinical findings. Swelling, erythema, pain; fever; increase in
inflammatory markers; locoregional lymphadenitis.
▶ Imaging
● Sonography (▶ Fig. 8.20a): hypoechogenic mass with internal
echoes; thickened walls.
● Mammography (▶ Fig. 8.20b): hyperdensity, nonspecific.
● Breast MRI (▶ Fig. 8.20c): mass:
○ T1W precontrast image: hypointense, nonspecific.
○ T2W: hyperintense, nonspecific.
○ After administration of contrast medium: obligatory strong
enhancement of the thickened abscess wall; reactive hyperemia of the surrounding structures.

c

Fig. 8.19 Old fat necrosis. Oil cysts. (a) Ultrasound image.
(b) Mammogram. (c) T1W precontrast breast MR image.

Note
The therapeutic management of an abscess of the breast is identical to that of abscesses in other areas of the body.

131


Imaging of Breast Lesions

Fig. 8.20 Abscess. (a) Ultrasound
image. (b) Mammogram. (c) Contrast-enhanced breast MRI subtraction image.

a

b

8

c

▶ Differential diagnosis. Carcinoma with central necrosis, triple-negative carcinoma.

▶ Implications for work-up/treatment. None if symptom free.
When there is uncertainty in the differential diagnosis, percutaneous biopsy should be undertaken.

8.1.21 Postoperative Scars

▶ Shape. Irregular.

A postoperative scar is the final stage of wound healing, with the
formation of a tissue complex that is fiber-rich, hypocellular, and
hypovascularized. The scar formation is complete approximately
3 to 6 months after surgery.

▶ Margins. Indistinct.

▶ Characteristics
● Incidence: inevitable after surgery; occasionally after vacuumassisted biopsy or trauma.
● Peak age: all age groups.
● Multifocality: following surgery in multiple ipsilateral locations.
● Bilateral occurrence: following bilateral surgery.
● Complications: none.
● Risk of malignancy: 0%.
● Prognosis: excellent.
● Histological classification after biopsy: B2.

132

▶ Internal composition. Nonproliferative tissue.
▶ Clinical findings. Scar located in the skin. Occasional skin
retraction. In the case of larger scars, an induration may be
palpable.
▶ Imaging
Sonography (▶ Fig. 8.21a): hypoechogenic area, posterior acoustic extinction, nonspecific.
● Mammography (▶ Fig. 8.21b): hyperdensity, occasionally associated with micro- and macrocalcifications, nonspecific.

● Breast MRI (▶ Fig. 8.21c): non-space-occupying lesion (nonmasslike lesion):
●


8.2 Findings with Ambiguous Biological Potential

b

a

8

c

Fig. 8.21 Postoperative scar. (a) Ultrasound image. (b) Mammogram. (c) T1W precontrast breast MR image with susceptibility artifacts (black dots).

T1W precontrast image: hypointense, nonspecific, frequently
associated with susceptibility artifacts due to perioperative
electrocautery.
○ T2W: isointense, occasionally hyperintense, nonspecific.
○ After administration of contrast medium: typically, no enhancement; occasional mild enhancement (protracted wound healing
or accompanying granulomatous inflammatory changes).
○

Note
Contrast-enhanced breast MRI enables reliable differentiation
between a postoperative scar and a potential tumor recurrence in
the vicinity of the scar.

▶ Differential

carcinoma.

diagnosis. Radial

scar,

recurrence,

breast

8.2 Findings with Ambiguous
Biological Potential
8.2.1 Papillomas
Breast papillomas are intraductal proliferations made up of
benign epithelial cells covering a central branching, fibrovascular
core. The solitary papilloma, typically located in the retromamillary region, is distinguished from the usually multiple peripheral
papillomas.
▶ Characteristics
● Incidence: rare.
● Peak age: 40 to 50 years.
● Multifocality: frequent in the case of the peripheral papilloma.
● Bilateral occurrence: frequent.
● Complications: none.

133


Imaging of Breast Lesions
●

●
●

Risk of malignancy: for solitary papillomas, ca. 2 to 5%; for
peripheral papillomas, ca. 10%.
Prognosis: excellent after complete excision of the lesion.
Histological classification after biopsy: B3.

▶ Implications for work-up/treatment. Management should
be determined in an interdisciplinary conference. Complete surgical or percutaneous vacuum-assisted excision is commonly recommended due to the increased risk of malignant
transformation. For small lesions, follow-up imaging may be recommended as an alternative.
▶ Shape, distribution. Round or oval, solitary or segmental.
▶ Margins. Circumscribed.

▶ Clinical findings. Pathologic secretion from the corresponding
lactiferous duct is occasionally the presenting clinical symptom
but usually there are no clinical findings.
▶ Imaging
Sonography (▶ Fig. 8.22a): hypoechogenic mass, nonspecific;
small findings are frequently occult.
● Mammography: hyperdensity, occasionally associated with
microcalcifications, nonspecific.
● Galactography (▶ Fig. 8.22b): intraductal filling defects and ductal cutoff.
● Breast MRI (▶ Fig. 8.22c): focus, mass:
○ T1W precontrast image: isointense, nonspecific.
○ T2W: isointense, occasionally hyperintense, nonspecific.
○ After administration of contrast medium: mild to strong enhancement; rarely displays ring enhancement.
●

▶ Internal composition. Proliferative tissue.

8

a

b

c

Fig. 8.22 Papillomas. (a) Ultrasound image of a solitary papilloma. (b) Galactogram showing numerous peripheral papillomas. (c) Maximum
intensity projection of a contrast-enhanced breast MR image demonstrating peripheral papillomas.

134