Breast

• Breast


  • Major function is for nutritional support of the infant
  • Structure of the organ undergoes marked periodic changes
  • It is visible, hence socially, culturally, and personally significant
• Major structures of the breast

  • Ducts
  • Lobules
• Types of epithelial cells in the breast

  • Luminal epithelial cells
  • Myoepithelial cells
• Types of stroma in the breast

  • Interlobular stroma
  • Intralobular stroma
• 1. 10 major duct orifices open onto the skin surface at the nipples
• Structure of the breast duct

  1. Superficial portion is lined by keratinizing squamous cells that change to the double-layered epithelium of the remainder duct

  2. The terminal duct branches into a grape-like cluster of small acini to form a lobule
• In pre-pubertal female and in males, the large duct ends at the terminal ducts
• Only with the onset of pregnancy does the breast become completely mature and functional
• By the end of pregnancy, the breast is composed almost entirely of lobules separated by scant stroma
• Changes in the breast after birth

  1. Immediately after birth, the lobules produce colostrum (high in proteins), changing to milk (high in fat and calories) over the next 10 days as the progesterone levels drop

  2. Upon cessation of lactation, epithelial cells undergo apoptosis and the lobules regresses, but full regression does not occur and as a result pregnancy causes permanent increase in the size and the number of lobules
• Changes in the breast after the 3rd decade

  The lobules and stroma start to involute, the interlobular stroma converts from radiodense stroma to radiolucent adipose tissue
• Milk Line Remnants


  Supernumerary nipples or breasts result from the persistence of epidermal thickenings along the milk line, which extends from the axilla to the perineum
• The disorders that normally affect the normal breasts in their normal positions, rarely affect these heterotropic, hormone-responsive foci
• Accessory Axillary Breast Tissue

  • Normal ductal system extends into the subcutaneous tissue of the chest wall or the axillary fossa (axillary tail of Spence)
  • Breast tissue may not be removed in these areas
  • Mastectomies reduce, but not eliminate, risk of breast cancer
• Congenital Nipple Inversion


  • Failure to evert during development, common, may be unilateral
  • Little significant, spontaneously correct during pregnancy
  • Acquired retraction is more of concern, since it may indicate presence of an invasive caner or an inflammatory nipple disease
• Pain (Mastalgia or Mastodynia)


  • Diffuse cyclic pain may be due to premenstrual edema
  • Non-cyclic pain is usually localized to one area of the breast and may be caused by ruptured cysts, physical injury and infections
• Palpable Masses


  • Most common palpable lesion are cysts, fibroadenomas, and invasive carcinomas
  • Benign palpable masses are most common in premenopausal
  • Malignancy increases with age
  • 50% are located in the upper outer quadrant, 10% in the remaining quadrants, 20% in the central or subareolar region
• Nipple Discharge


  • Small discharge upon breast manipulation
  • Milky discharge (galactorrhea) is associated with ↑prolactin
  • Bloody or serous discharge are most commonly due to large duct papillomas and cysts
  • During pregnancy, bloody discharge can result from rapid growth and remodeling of the breasts
  • Risk of malignancy increases with age, associated with carcinoma (7%) in women younger than 60, but in 30% of older women
• Mammographic screening


  • Most common means to detect breast cancer
  • Sensitivity and specificity increases with age due to replacement of fibrous, radiodense tissue with fatty radiolucent tissue in older women
  • Lesions that replace adipose tissue, rounded densities are benign such as fibroadenomas, cysts
  • Invasive carcinomas form irregular masses
  • Calcifications associated with benign lesions are clusters of apocrine cysts, hyalinized fibroadenomas, and sclerosing adenosis
  • Those associated with malignancy are small, irregular, numerous, and clustered
  • Most common detected is ductal carcinoma in situ (DCIS)
• Ultrasonography


  Either cystic or solid
• MRI


  Dense breast, extent, occult, implant rupture
• Acute Mastitis


  • Typically occur during 1st month of breastfeeding caused by local bacterial infection when the breast is most vulnerable to cracks and fissures of the nipples
  • S. aureus or less commonly streptococci invade breast tissue
  • Breast is erythematous and painful with fever
  • At the outset, only 1 duct system is affected but may spread if not treated
  • Staphylococci abscesses may be single or multiple, Streptococci cause spreading infection in the form of cellulitis
• Squamous Metaplasia of Lactiferous Ducts

  • Recurrent subareolar abscess, periductal mastitis, Zuska disease
  • Painful erythematous subareolar mass - bacterial abscess
  • Fistula tract often tunnels under the smooth muscle of the nipple and opens onto the skin at the edge of the areola
  • Many have inverted nipple, more than 90% are smokers
• Morphology of Squamous Metaplasia of Lactiferous Ducts

  1. Keratinizing squamous metaplasia of the nipple ducts

  2. Keratin shed plugs the ductal system, causing dilation & rupture

  3. Intense chronic granulomatous inflammatory response

  4. With recurrence, secondary anaerobic bacterial infection may supervene and cause acute inflammation
• Duct Ectasia


  • Palpable perioareolar mass, associated with thick, white nipple secretions and occasionally with skin retraction
  • Pain and erythema are uncommon
  • Tends to occur in 5th – 6th decade of life, in multiparous women
  • Not associated with smoking
  • Mimics the clinical and radiographic appearance of invasive CA
• Morphology of Duct Ectasia

  1. Ectatic dilated ducts filled with inspissated secretions and numerous lipid-laden macrophages

  2. When ruptured, marked periductal and interstitial chronic inflammatory reaction ensues

  3. Granulomas may form around cholesterol deposits
• Fat Necrosis


  • Protean, closely mimic cancer, painless palpable mass, skin thickening/retraction, or mammographic densities/calcification
  • Half have history of breast trauma or prior surgery
• Morphology of Fat Necrosis

  1. Acute lesions may be hemorrhagic and contain central areas of liquefactive fat necrosis with neutrophils and macrophages

  2. Proliferating fibroblasts and chronic inflammatory cells over the next few days surround the injured area

  3. Replaced by scar tissue, or encircled by fibrous tissue
• Lymphocytic Mastopathy (Sclerosing Lymphocytic Lobulitis)

  • Presents with single or multiple hard palpable masses or mammographic densities
  • Difficult to obtain tissue with needle biopsy due to dense collagenized stroma
  • Atrophic ducts and lobules have thickened basement membranes surrounded by a prominent lymphocytic infiltrate
  • Most common in type 1 diabetes or autoimmune thyroid disease
• Granulomatous Mastitis


  • Manifestation of systemic granulomatous disease such as Wegener's granulomatosis, sarcoidosis, tuberculosis
  • Granulomatous lobular mastitis is uncommon occurs only in parous women, closely associated with lobules suggesting it may be caused by hypersensitivity reactions during lactation
  • Cystic neutrophilic granulomatous mastitis caused by Corynebacteria share common histologic pattern with granulomatous lobular mastitis
• Classification of Benign Epithelial Lesions

  • Non-proliferative breast changes
  • Proliferative breast disease
  • Atypical Hyperplasia
• Non-Proliferative Breast Changes (Fibrocystic Change)

  • Might mean "lumpy bumpy" breasts on palpation
  • Dense breast with cyst with benign histologic changes
• Morphology of Non-Proliferative Breast Changes

  1. Cystic change often with apocrine metaplasia

  2. Fibrosis

  3. Adenosis
• Cystic change with apocrine metaplasia

  • Small cysts form by the dilation of the lobules, in turn may coalesce to form larger cysts
  • Contains turbid, semi-translucent fluid of a brown or blue color
  • Lined by flattened atrophic epithelium or metaplastic apocrine cells which have abundant granular, eosinophilic cytoplasm and rounded nuclei and closely resemble the normal apocrine glands
  • Calcifications are common
  • Cysts cause concern when they are solitary and firm on palpation
  • Diagnosis is confirmed by disappearance of the mass on FNAB
• Fibrosis


  • Cysts frequently rupture releasing secretory materials
  • The resulting chronic inflammation and fibrosis contribute to the palpable nodularity of the breasts
• Adenosis


  • Increase in number of acini per lobule
  • Normal feature of pregnancy
  • Can occur in non-pregnant women as focal changes
  • Calcifications are occasionally present within lumens
  • Acini are lined by columnar cells which may appear benign or show atypia (flat epithelial atypia)
  • Flat epithelial atypia is a clonal proliferation associated with deletions in chromosome 16q, earliest recognizable precursor of low-grade breast cancers, but does not convey an increased risk
  • Lactational adenomas – present as palpable masses in pregnancy or lactating women, consisting of normal-appearing breast tissue with lactational changes
• Proliferative Breast Disease without Atypia

  • Associated w/ small increase in risk of carcinoma of either breast
  • Commonly detected as mammographic densities, calcifications, or incidental findings in biopsies
  • Non-clonal lesions
  • Predictors of risk but unlikely to be true precursors of carcinoma
• Morphology of Proliferative Breast Disease without Atypia

  1. Epithelial Hyperplasia

  2. Sclerosing Adenosis

  3. Complex Sclerosing Lesion

  4. Papillomas
• Epithelial Hyperplasia


  • Normal breast ducts and lobules are lined by double layer of myoepithelial and luminal cells
  • In epithelial hyperplasia, increased number of both cells fills and distends the ducts and lobules
  • Irregular lumens can often be discerned at periphery of masses
• Sclerosing Adenosis


  • Increased number of acini that are compressed and distorted in the central portion of the lesion
  • Stromal fibrosis may completely compress the lumens to create the appearance of sloid cords or double strands of cells with dense stroma, mimicking invasive CA
  • Palpable mass, radiologic density, calcifications