Cysts

The simple cyst is a fluid-filled cavity with a lining consisting of an inner epithelial layer and an outer myoepithelial layer.

Characteristics

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  Incidence: very common.

  
  
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  Peak age: all age groups; incidence decreases after menopause.

  
  
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  Multifocality: frequent.

  
  
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  Bilateral occurrence: frequent.

  
  
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  Complications: none.

  
  
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  Risk of malignancy: less than 1%.

  
  
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  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 Circumscribed.

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.

Imaging

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  Sonography (▶ Fig. 8.1a): Anechoic mass; posterior acoustic enhancement; unambiguous sonographic finding.

  
  
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  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.

  
  
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  Breast MRI (▶ Fig. 8.1c): mass:

  
  
  
  
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    T1W precontrast image: hypointense.

    
    
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    T2W image: hyperintense.

    
    
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    After administration of contrast medium: no enhancement.

    
    
    
    

    
    

    Note

    
    

    
    

    Mammography cannot reliably distinguish between a cyst (fluid-filled) and a proliferative process (solid tissue).

    
    
    
    

    

    
    

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

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

8.1.2 Inflamed Cysts

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

Characteristics

• 
  

  Incidence: rare.

  
  
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  Peak age: all age groups; incidence decreases after menopause.

  
  
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  Multifocality: rare.

  
  
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  Bilateral occurrence: rare.

  
  
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  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.

Internal composition Homogeneous fluid.

Clinical findings Small cysts normally have no correlative clinical findings. In the case of larger cysts, a circumscribed, firm-elastic, occasionally tender mass may be palpable.

Imaging

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  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.

    
    
    
    

    
    

    Note

    
    

    
    

    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.

    
    
    
    

    

    
    

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

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

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.

  
  
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  Multifocality: rare.

  
  
• 
  

  Bilateral occurrence: rare.

  
  
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  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, firm-elastic mass may be palpable. The lesions are rarely tender to palpation.

Imaging

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  Sonography (▶ Fig. 8.3a): hypoechoic mass; minor posterior acoustic enhancement (protein), moderate acoustic enhancement to acoustic extinction (old blood).

  
  
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  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:

  
  
  
  
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    T1W precontrast image: isointense (protein) to hypointense (old blood); sedimentation may be visible.

    
    
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    T2W image: isointense (protein) to hypointense (old blood); sedimentation may be visible.

    
    
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    After administration of contrast medium: no to slight cyst wall enhancement.

    
    
    
    

    
    

    Note

    
    

    
    

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

    
    
    
    

    

    
    

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

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).

Characteristics

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  Incidence: frequent.

  
  
• 
  

  Peak age: 18 to 50 years.

  
  
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  Multifocality: frequent.

  
  
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  Bilateral occurrence: frequent.

  
  
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  Complications: usually none. The juvenile giant fibroadenoma is an exception due to its massive size (diameter up to 12–15 cm).

  
  
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  Risk of malignancy: 0%.

  
  
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  Prognosis: excellent.

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

Shape Lobular, oval.

Margins Circumscribed.

Internal composition Homogeneous, proliferative tissue.

Clinical findings Small cysts normally have no correlative clinical findings. In the case of larger myxoid fibroadenomas, circumscribed lumps may be palpable.

Imaging

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  Sonography (▶ Fig. 8.4a): homogeneous, isoechoic mass; longitudinal axis parallel to the skin; mild elasticity; mild posterior acoustic enhancement.

  
  
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  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.

  
  
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  Breast MRI (▶ Fig. 8.4c): focus, mass:

  
  
  
  
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    T1W precontrast image: hypointense.

    
    
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    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.

    
    
    
    

    

    
    

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

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).

Characteristics

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  Incidence: frequent.

  
  
• 
  

  Peak age: 40 to 80 years.

  
  
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  Multifocality: frequent.

  
  
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  Bilateral occurrence: frequent.

  
  
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  Complications: none.

  
  
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  Risk of malignancy: 0%.

  
  
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  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

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  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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  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).

  
  
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  Breast MRI (▶ Fig. 8.5c): focus, mass:

  
  
  
  
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    T1W precontrast image: isointense; endotumoral signal loss in the case of macrocalcifications.

    
    
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    T2W image: isointense; endotumoral signal loss in the case of macrocalcifications.

    
    
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    After administration of contrast medium: minor or no enhancement.

    
    
    
    

    
    

    Note

    
    

    
    

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

    
    
    
    

    

    
    

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

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

8.1.6 Adenoma

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.

Characteristics

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  Incidence: rare.

  
  
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  Peak age: usually in younger women up to 50 years of age.

  
  
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  Multifocality: rare.

  
  
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  Bilateral occurrence: rare.

  
  
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  Complications: none.

  
  
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  Risk of malignancy: 0%.

  
  
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  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 ultrasound-guided, core needle biopsy should be undertaken.

Shape Round, oval, lobular.

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

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  Sonography (▶ Fig. 8.6a): homogeneous, isoechoic mass; longitudinal axis parallel to the skin; good elasticity; mild posterior acoustic enhancement.

  
  
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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.

  
  
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  Breast MRI (▶ Fig. 8.6c): focus, mass:

  
  
  
  
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    T1W precontrast image: hypointense.

    
    
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    T2W image: hyperintense.

    
    
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    After administration of contrast medium: moderate to strong homogeneous 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).

    
    
    
    

    

    
    

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

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

8.1.7 Hamartoma

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

Characteristics

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  Incidence: rare.

  
  
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  Peak age: all age groups.

  
  
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  Multifocality: rare.

  
  
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  Bilateral occurrence: rare.

  
  
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  Complications: none.

  
  
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  Risk of malignancy: 0%.

  
  
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  Prognosis: excellent.

  
  
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  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.

Margins Circumscribed; the lesion displays a pseudocapsule.

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

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  Sonography (▶ Fig. 8.7a): inhomogeneous mass with echogenicity depending upon the composition (fat and parenchymal components).

  
  
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  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.

  
  
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  Breast MRI (▶ Fig. 8.7c): mass:

  
  
  
  
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    T1W precontrast image: mixed presentation (hypointense to hyperintense), depending upon composition.

    
    
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    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.

    
    
    
    

    

    
    

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

Differential diagnosis Phyllodes tumor.

8.1.8 Lipoma

The lipoma (synonym: adipose tumor) is an encapsulated tumor that contains exclusively mature adipose cells.

Characteristics

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  Incidence: rare.

  
  
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  Peak age: all age groups.

  
  
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  Multifocality: rare.

  
  
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  Bilateral occurrence: rare.

  
  
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  Complications: none.

  
  
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  Risk of malignancy: 0%.

  
  
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  Prognosis: excellent.

  
  
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  Histological classification after biopsy: B2.

Implications for work-up/treatment None.

Shape Oval.

Margins Circumscribed, displays a delicate capsule.

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

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  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).

  
  
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  Mammography (▶ Fig. 8.8b): hypodense (fat-equivalent) mass with delicate surrounding capsule; no associated microcalcifications.

  
  
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  Breast MRI (▶ Fig. 8.8c): mass:

  
  
  
  
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    T1W precontrast image: hyperintense.

    
    
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    T2W image: hyperintense; hypointense in T2W fat-suppressed.

    
    
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    After administration of contrast medium: no enhancement.

    
    
    
    

    
    

    Note

    
    

    
    

    Liposarcoma does not develop from a breast lipoma.

    
    
    
    

    

    
    

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

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.

Characteristics

• 
  

  Incidence: frequent.

  
  
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  Peak age: all age groups.

  
  
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  Multifocality: frequent.

  
  
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  Bilateral occurrence: frequent.

  
  
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  Complications: none.

  
  
• 
  

  Risk of malignancy: not increased.

  
  
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  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, 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.

Imaging

• 
  

  Sonography (▶ Fig. 8.9a): nonspecific inhomogeneous, hypoechogenic area, frequently occult.

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

  
  
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  Breast MRI (▶ Fig. 8.9c): non-space-occupying lesion (nonmasslike lesion):

  
  
  
  
  • 
    

    T1W precontrast image: intermediary signal, nonspecific.

    
    
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    T2W image: intermediary signal, nonspecific.

    
    
  • 
    

    After administration of contrast medium: mild to strong enhancement, nonspecific.

    
    
    
    

    
    

    Note

    
    

    
    

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

    
    
    
    

    

    
    

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

Differential diagnosis Adenosis, DCIS, ILC.

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 ▶ 8.2.2).

Characteristics

• 
  

  Incidence: frequent.

  
  
• 
  

  Peak age: all age groups.

  
  
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  Multifocality: frequent.

  
  
• 
  

  Bilateral occurrence: frequent.

  
  
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  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.

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.

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 false-positive findings on breast MRI because it exhibits an irregular shape and is often associated with increased perfusion.

    
    
    
    

    

    
    

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