BREAST Flashcards
1
Q
BENIGN LESIONS WITH TYPICAL
IMAGING APPEARANCES
A
- Fibroadenoma—involuting fibroadenomas may contain typical
‘popcorn’ calcification on mammography, which precludes the
need for further imaging or biopsy. In the UK national guidance
recommends that biopsy in women <25 years is not necessary for
confirmation if typical features of a fibroadenoma are present
(well-defined, ovoid/round, up to three gentle lobulations). Other
countries follow BIRADS recommendations, which advocate US
follow-up. - Intramammary lymph node—most often in the upper outer
quadrant. A fatty hilum is a characteristic feature, typically seen in
normal and reactive lymph nodes, but may also be present in
pathological nodes—this is seen as a focal radiolucency within
the node on mammography (may be difficult to appreciate),
fat signal on MRI or hyperechoic on US. Normal or reactive
nodes often have ‘suspicious’ enhancement characteristics
on MRI. - Lipoma—well-defined, rounded, exclusively fat-containing.
- Oil cyst—well-defined, lucent on mammography ± ‘egg-shell’
peripheral calcification. The presence of multiple subcutaneous oil
cysts is characteristic for steatocystoma multiplex (many other
subcutaneous oil cysts will also be present on the trunk). - Hamartoma—‘breast tissue within breast tissue’ or ‘salami-slice’
appearance on imaging due to variable mix of fatty and glandular
tissue
2
Q
SINGLE WELL-DEFINED MAMMOGRAPHIC
SOFT-TISSUE OPACITY
Benign
A
- Cyst—round/oval, low-density mass. In the case of an oil cyst: rounded, fat density mass ± peripheral calcification.
- Fibroadenoma—round/oval mass, similar density to glandular breast parenchyma. Cysts and fibroadenomas can have similar appearances on mammography.
- Intramammary lymph node—common in normal breasts.
- Skin lesion—e.g. irregular ‘warty’ skin papillomas. The air/soft-tissue interface creates a characteristic hypodense halo around skin lesions. Skin markers may be used to confirm.
5. Nipple not in profile—may resemble a soft-tissue opacity on the mediolateral oblique (MLO) view.
- Hamartoma—variable appearance depending on composition—if mostly glandular tissue it can present as a well-defined mass with density identical to surrounding glandular parenchyma. If mostly fatty, it can present as a well-defined lucent mass.
- Galactocoele—round/oval mass in a lactating woman. Appearance depends on proportion of fat, water and milk content. May mimic lipoma (if high fat content), hamartoma (if mixed viscous contents) or cyst. May contain characteristic fat-fluid level if contains fresh liquid milk. Can become infected.
- Sebaceous cyst—opacity related to the dermis.
- Lactating adenoma—occurs during lactation or in the third trimester of pregnancy. Imaging features are similar to fibroadenoma. Regresses spontaneously after cessation of breast feeding.
- Pseudoangiomatous stromal hyperplasia (PASH)—the rare
tumoural form presents as a well-defined, noncalcified mass in a
premenopausal woman. Can mimic fibroadenoma on US. - Myofibroblastoma—rare benign spindle cell tumour usually found in postmenopausal women and older men. Well-defined, round/oval, noncalcified mass, hypoechoic on US, mimicking fibroadenoma (patient age can be a useful discriminator).
- Other rare soft-tissue masses not specific to the breast—e.g. haemangioma (± phleboliths), leiomyoma (often near areola), schwannoma, neurofibroma, solitary fibrous tumour. These are typically well-defined and hypoechoic on US (mimicking fibroadenoma), although haemangiomas may be microlobulated and have variable echogenicity.
3
Q
SINGLE WELL-DEFINED MAMMOGRAPHIC
SOFT-TISSUE OPACITY
Malignant
A
- Carcinoma—a small number of carcinomas can look ‘benign’ on
mammography: high-grade invasive ductal carcinoma, mucinous
carcinoma (often mixed solid-cystic), medullary carcinoma,
papillary carcinoma (often within a cyst or dilated duct) and
adenoid cystic carcinoma. - Phyllodes tumour—indistinguishable from a fibroadenoma on
mammography, but characterized by its rapid growth and often
large by time of presentation. Usually present in an older age
group than fibroadenomas. Most are benign, but borderline and
malignant varieties exist. Calcification is rare. Malignant lesions
metastasize to lung and bone, and may invade the chest wall. - Metastasis to the breast—can be solitary, see Section 11.5.
- Lymphoma*—can appear as a single, well-defined, noncalcified
mass. Spiculations and architectural distortion are usually absent.
May be primary (rare) or secondary.
4
Q
MULTIPLE WELL-DEFINED
MAMMOGRAPHIC SOFT-TISSUE
OPACITIES
A
- Cysts—most common cause.
- Fibroadenomas—10-20% are multiple.
- Skin lesions—e.g. cutaneous papillomas, neurofibromas (NF1).
- Intramammary lymph nodes.
- Metastases—lymphoma, leukaemia (especially acute myeloid
leukaemia), melanoma, lung and ovaries are the most common
sources. Often involve the subcutaneous fat. Calcification is rare
(except in ovarian cancer). Metastases elsewhere are usually also
present. - Silicone or paraffin injections—usually very dense and widely
distributed in the breast, accompanied by dense striated appearing
fibrosis (sclerosing lipogranulomatosis) ± dense calcification. - Cowden syndrome—may present with multiple fibroadenomas,
fatty hamartomas and/or tubular adenomas. Increased risk of
breast cancer.
5
Q
LARGE (>5 CM) WELL-DEFINED
MAMMOGRAPHIC ABNORMALITY
A
- Giant cyst—radiopaque, usually low density.
- Giant fibroadenoma—radiopaque.
- Lipoma—radiolucent.
- Phyllodes tumour—radiopaque, indistinguishable from fibroadenoma.
- Hamartoma—mixed density, depending on composition of fatty
and glandular tissue.
6
Q
BENIGN BREAST CONDITIONS THAT MIMIC MALIGNANCY
2
A
- Microcalcification
(a) Sclerosing adenosis—calcification can have suspicious appearances (e.g. clustered/pleomorphic) resembling ductal carcinoma in situ (DCIS).
(b) Amyloidosis*—can produce suspicious microcalcification.
(c) Pseudoxanthoma elasticum—can produce microcalcifications in the breast, vessels and skin (especially in the axilla)—if all three are present this is highly suggestive of the diagnosis.
(d) Other causes of skin calcification—e.g. chronic renal failure. - Suspicious soft-tissue opacity
(a) Summation of normal tissues—giving the impression of a suspicious abnormality on mammography. A common reason for recall after screening mammography. Small paddle compression or tomosynthesis can help separate the individual components.
(b) Fibroadenoma/cyst—when one margin appears ill-defined.
(c) Fat necrosis—typically seen after surgery, radiotherapy or trauma. Usually superficial. Ill-defined in the early stages ± a radiolucent centre. Often hyperechoic on US (a helpful feature as malignancy is usually hypoechoic). Often contains ‘malignant-appearing’ dystrophic calcification peripherally,
which progresses with time. In later stages it usually becomes well-defined, resulting in an oil cyst, but if it heals with prominent fibrosis it can mimic a spiculated mass.
(d) Postbiopsy scar.
(e) Radial scar (<1 cm)/complex sclerosing lesion (>1 cm)—
presents as a distortion on mammography or a spiculate lesion with a low density centre—‘black star’ appearance (malignancy tends to have a higher density centre). As there is a risk of associated carcinoma, these lesions are usually widely sampled with image-guided vacuum excision—there is
currently a move away from surgical excision.
(f) Haematoma—varied appearance. Usually a history of trauma, but not always. Resolves over time, but may evolve into fat necrosis or a seroma.
(g) Irregular skin lesion—e.g. wart. Look for the tell-tale hypodense halo.
(h) PASH—may have indistinct borders (Pseudoangiomatous stromal hyperplasia (PASH) is a benign mesenchymal proliferative lesion of the breast that may present clinically as a mass)
(i) Lymphocytic mastitis—ill-defined mass or masses with marked posterior acoustic shadowing on US (often more than would be expected with malignancy). Usually associated with diabetes (aka diabetic mastopathy) or autoimmune diseases such as Hashimoto thyroiditis, SLE or Sjögren’s
syndrome.
(j) Wegener’s granulomatosis, sarcoidosis and amyloidosis*—any of these can rarely produce an irregular breast mass or masses, usually in the context of widespread disease elsewhere, therefore the diagnosis may already be suspected (although biopsy is still required to exclude malignancy).
(k) Eosinophilic mastitis—very rare. Usually accompanied by peripheral eosinophilia. Can present as an ill-defined mass or an oedematous/inflamed breast.
(l) Other rare soft-tissue masses not specific to the breast—e.g. desmoid tumour (usually close to pectoral muscles), nodular fasciitis (usually located on the subcutaneous fascia), granular cell tumour (may be well- or ill-defined, usually upper inner quadrant in supraclavicular nerve territory),
inflammatory pseudotumour, Rosai-Dorfman disease. All of these appear as nonspecific, ill-defined masses indistinguishable from malignancy.
7
Q
OEDEMATOUS BREAST
Causes without erythema/inflammation
A
- Previous surgery/radiotherapy—common, particularly after
axillary clearance (obstructing lymphatic drainage). Oedema is
most pronounced 6–12 months after treatment, and gradually
resolves, usually within 1–3 years. Malignant axillary nodes may
also obstruct lymphatic drainage. - Venous obstruction—e.g. subclavian vein occlusion.
- Heart failure/nephrotic syndrome—more commonly bilateral
but can be unilateral, e.g. if patient always lies on one side
in bed. - Angioedema—rare.
8
Q
OEDEMATOUS BREAST
Causes with erythema/inflammation
A
- Mastitis
(a) Acute infectious mastitis—clinical signs of infection. Most
common in lactating women. Increased echogenicity in
inflamed fat lobules, hypoechoic areas in glandular tissue ±
duct ectasia. May be associated with an abscess, presenting as
an irregular mass on mammogram and US.
(b) Zuska’s disease—usually in nonlactating smokers. Caused by
epithelial squamous metaplasia obstructing the lactiferous
ducts in the nipple–areola complex, resulting in duct ectasia,
recurrent infection, subareolar abscess formation and a
lactiferous fistula. Surgical excision of the abscess, fistula and
involved lactiferous duct is required for definitive treatment.
(c) Granulomatous mastitis
(i) Idiopathic granulomatous lobular mastitis—usually in
young women <5 years after childbirth. Ill-defined mass
with inflammatory change ± fistulation with skin ± axillary
adenopathy. The mass is usually wider than tall and may
have tubular components on US. Other causes of
granulomatous inflammation (e.g. sarcoidosis, Wegener’s,
TB, fungal infection) must be excluded.
(ii) TB*—three patterns: nodular (ill-defined mass ±
cutaneous fistulation), diffuse (breast oedema + skin
thickening) and sclerosing (fibrosis + architectural
distortion + reduced breast size). Axillary adenopathy is
common and if nodal calcification is present this suggests
TB. Breast macrocalcification may be present but
microcalcification is rare.
(iii) Actinomycosis—may be primary (inoculation via the
nipple) or secondary (direct extension from intrathoracic
disease). Primary disease presents as an ill-defined
retroareolar mass ± cutaneous fistulation ± breast
oedema, without calcification or adenopathy. Secondary
syphilis (very rare) and TB can have similar appearances. - Inflammatory carcinoma—can mimic mastitis. Usually a short (<3
months) history of symptoms. Trabecular thickening and skin
thickening on mammography. Altered echogenicity ± mass on US
with skin thickening. Microcalcifications and axillary adenopathy
may also be present. The inflammation is caused by the tumour
obstructing the subcutaneous lymphatics. - Localized scleroderma of the breast (morphea)—can mimic
inflammatory carcinoma. More common in younger patients.
9
Q
ARCHITECTURAL DISTORTION ON
MAMMOGRAPHY WITHOUT A
VISIBLE MASS
A
- Radial scar/complex sclerosing lesion—see Section 11.7.
- Invasive breast cancer—the presence of a correlative abnormality
on US significantly increases the probability of malignancy. - DCIS—suspicious microcalcification is usually also present.
- Sclerosing adenosis—microcalcification may also be present.
- Scarring or fat necrosis post biopsy/surgery/infection/trauma—
clinical history is key. Dystrophic calcification may be present
10
Q
SHRUNKEN BREAST
3
A
- Following radiotherapy/trauma/burns—clinical history important. Dystrophic calcification is common. Thoracic radiotherapy in childhood can result in longstanding breast asymmetry due to stunted breast development.
- Breast cancer—especially invasive lobular carcinoma, where a discrete mass may not be visible on mammography.
- TB*—particularly the sclerosing form
11
Q
MAMMARY DUCT DILATATION
Benign
5
A
- Duct ectasia—Dilated subareolar ducts ± debris on US, due to chronic inflammation/fibrosis leading to duct blockage. On a spectrum alongside plasma cell mastitis, periductal mastitis and Zuska’s disease (breast duct fistulas and recurrent abscesses located in and about the nipple).
- Physiological changes during lactation.
- Blocked ducts—during lactation due to sedimented secretions. Echogenic material in dilated ducts on US.
- Papilloma—well-defined intraductal mass with associated duct dilatation. Usually solitary in a central duct, but may be multiple in distal ducts (papillomatosis). Highly vascular ± a vascular stalk on colour Doppler. May contain calcification.
- Apocrine metaplasia—associated with fibrocystic disease. Consists of dilated ducts and adjacent septated cysts ± inspissated/calcified secretions. Often seen in patients with extensive cystic disease
12
Q
DUCT DILATATION
Malignant
A
- Ductal carcinoma in situ—can present as an intraductal mass with
duct dilatation (seen on US as a soft-tissue mass filling a duct). - Intraductal papillary carcinoma—indistinguishable from a benign
papilloma on imaging. - Invasive ductal carcinoma—an irregular mass extending into a
duct (and therefore widening the duct) is a highly specific sign of
malignancy, but is not commonly seen in isolation.
13
Q
AXILLARY LYMPHADENOPATHY
A
- Nonspecific reactive hyperplasia—enlarged nodes with preserved
fatty hila and normal node morphology. Idiopathic. - Malignancy—usually from breast cancer. Other common sources
include lymphoma, leukaemia, melanoma. Involved nodes often
lose their fatty hilum and elongated shape, becoming more
rounded. Other features include eccentric cortical thickening and
capsular irregularity. Involved nodes in lymphoma may be
markedly hypoechoic, almost cystic in appearance on US. Nodes
involved by metastatic thyroid or ovarian cancer may contain
peripheral amorphous calcification. Nodal microcalcification can
rarely be seen in breast cancer. - Infection—e.g. mastitis, soft-tissue infection in the arm, cat-scratch
disease, infectious mononucleosis, TB and HIV. Coarse nodal
calcification suggests TB (or sarcoidosis). - Silicone lymphadenopathy—in patients with silicone breast
implants that have ruptured/leaked or following silicone injections 344 Aids to Radiological Differential Diagnosis
into the breast. Silicone deposits in axillary nodes are very dense
on mammography and cause a ‘snowstorm’ appearance on US. - Connective tissue disease—e.g. rheumatoid arthritis, SLE,
psoriatic arthritis, dermatomyositis, scleroderma. Patients with a
history of gold salt therapy for rheumatoid arthritis may have
punctate high-density gold deposits within axillary nodes (similar
heavy metal nodal deposits can be seen in patients with large
tattoos on the arms). - Granulomatous disease—e.g. sarcoidosis, Wegener’s
granulomatosis
14
Q
MALE BREAST DISEASE
A
- Gynaecomastia—most common condition. Proliferation of
glandular tissue that is typically subareolar, central and
fan-shaped. Usually bilateral and asymmetrical. On US
gynaecomastia can have spiculated margins, resembling breast
carcinoma. In patients on hormonal therapy for gender
reassignment or prostate cancer, the gynaecomastia is marked
and may look similar to female breasts. - Pseudogynaecomastia—proliferation of fatty tissue only (no
glandular proliferation). - Male breast cancer—typically eccentric in location. Invasive
ductal carcinoma is the most common histological subtype.
Imaging features are similar to female breast cancer although
microcalcification is less common. Lesions looking like simple
cysts should be evaluated carefully as simple cysts do not
typically occur in men. Complex cysts should be biopsied—a
solid component within a cyst may represent papillary carcinoma
(or a benign intraductal papilloma). - Abscess—commonly subareolar in location, with ill-defined
margins ± surrounding trabecular thickening. Clinical signs of
infection are typically present. - Haematoma/fat necrosis—e.g. due to trauma.
- Metastases—rare. In men, prostate is the most common
source. - PASH—similar appearance to that seen in women.
- Diabetic mastopathy—similar appearance to that seen in
women.Breast disease and mammography 345
11 - Myofibroblastoma—rare, usually found in older men. Imaging
features similar to fibroadenoma (but fibroadenoma is
exceptionally rare in men). See Section 11.4. - Granulomatous mastitis—including TB and sarcoidosis. Very
rare. - Other soft-tissue masses not specific to the breast—e.g.
sebaceous cyst, lipoma and others (
15
Q
MRI IN BREAST DISEASE
Indications
A
- Evaluate local extent of cancer—when tumour size is uncertain
on conventional imaging (typically young women with dense
background breast tissue on mammography). Can also potentially
assess chest wall invasion. - Lobular carcinoma—may be mammographically occult and can
be multifocal/bilateral. - Metastatic axillary adenopathy of unknown primary—to identify
occult breast cancer. - High-risk screening—those with a history of mantle radiotherapy
or genetic mutation. - Evaluation of implant integrity.
- Monitor response to neoadjuvant chemotherapy.
