Benign breast lesions

Progression

• Mild ductal hyperplasia -> florid ductal hyperplasia -> atypical ductal hyperplasia -> DCIS
• Columnar cell change -> columnar hyperplasia -> flat epithelial atypia
• Fibroadenoma -> complex/giant fibroadenoma

Non-proliferative (RR of lifetime breast cancer ~1.2-1.4x)

Breast cysts

• • Pathophysiology
    • Fluid-filled, round or ovoid masses derived from the terminal duct lobular unit, lined with epithelium
    • Appear to arise from destruction and dilatation of lobules and terminal ductules - possibly fibrosis at or near the lobule, leading to expansion of a cavity if fluid continues to be secreted
    • Influenced by ovarian hormones
    • Vary in size from microscopic to large palpable masses containing up to 30mL of fluid
    • Intra-cystic cancer is found in 0.1% of aspirations (Sabiston)
  • Clinically
    • Palpable abnormality or cause of pain
    • Well-circumscribed borders, benign-feeling
    • 50% are multiple or recurrent
    • Common in women between 35 and 50 years old, rare after menopause (can occur with HRT)
    • Fluid can be straw-coloured, opaque, or dark green, and may contain debris
  • Diagnosis
    • USS to diagnose
      • Simple cyst - well-circumscribed, no septations or debris, thin walled
      • Complex - septations, solid component, thick wall
  • Management
    • Asymptomatic simple cysts - no intervention, reassure, does not need to be aspirated
    • Symptomatic simple cysts - observe or aspirate (if bloody aspirate, get cytopathology to exclude malignancy)
      • Remember, aspiration can change the architecture permanently, as a scar component can develop, making it harder to interpret future images (according to one breast surgeon)
    • Complex cysts - aspiration for cytology
      • Recurrence twice: consider tissue biopsy of solid elements (USS-guided with clip left in place)
    • Entire cyst can be removed with a vacuum-assisted core needle device
    • Surgical removal indications:
      • Multiple recurrences
      • Large and painful
      • Atypia on biopsy
      • Incomplete percutaneous removal

Galactocoele

• • Cystic collections of fluid, usually caused by an obstructed milk duct or inspissated milk within ducts
  • Generally occurs right after feeding has stopped or declined, but can occur 6-10 months after breastfeeding has ceased
  • Soft cystic masses on exam, usually found centrally or under the nipple
  • Mammography: indeterminate mass, may have classic fat-fluid level
  • USS may show a complex mass
  • Aspiration - thick, creamy material that may be tinged dark green or brown (appears purulent but is in fact sterile)
  • Treatment with large-bore needle aspiration
  • Excision is not necessary unless the cyst cannot be aspirated or becomes infected
  • No increased risk of cancer

Papillary apocrine change

• • Proliferation of ductal epithelial cells showing apocrine features, characterised by eosinophilic cytoplasm

Mild hyperplasia of the usual type/mild ductal hyperplasia

• • Increase in the number of epithelial cells within a duct that is more than two, but not more than four, cells in depth. Epithelial cells do no cross the lumen of the involved space.
  • Differentiate from florid ductal hyperplasia - less quantity

Columnar cell change/simple columnar alteration

• • Change of cuboid epithelium to columnar in lobules
  • <2 cell layers

Proliferative without atypia (RR of lifetime breast cancer ~1.7-2.1x)

Fibroadenoma

• • Epidemiology
    • Most common solid benign mass - 50% of all breast biopsies
    • Most commonly found 15-35yo, rare after 40yo
  • Pathophysiology
    • Benign solid tumours composed of stromal and epithelial elements
    • Risk of cancer is 0.2%
    • Simple
      • Benign solid tumours containing glandular as well as fibrous tissue
      • No increased risk of developing breast cancer
    • Complex
      • Contains other proliferative changes, such as sclerosing adenosis, duct epithelial hyperplasia, epithelial calcification, or papillary apocrine changes
      • Associated with slightly increased risk of cancer
    • Giant fibroadenoma
      • >10cm or >5cm depending on source
      • Excision recommended
    • Juvenile
      • <18yo
      • Surgical removal is curative, despite rapid growth
  • Presentation
    • Well-circumscribed, smooth edges, mobile, rubbery
    • May wax and wane with the menstrual cycle
    • Many patients will have multiple
    • Mildly symptomatic - tenderness or pain worse with menstruation or with pregnancy/COCP
  • Natural history
    • Usually become less symptomatic with age, often calcifying in post-menopausal women
  • Diagnosis
    • USS, especially in younger women - can readily distinguish between cysts and fibroadenomas
    • Mammogram is not particularly useful, but can show 'popcorn calcifications'
    • USS-guided biopsy confirms dx
  • Management
    • Observation if small and asymptomatic
    • Excision indications
      • >3cm in diameter
      • Symptomatic (patient decision)
      • Enlarging rapidly
      • Any suspicious pathological condition associated with the lesion (to exclude phyllodes tumour)
        • Stroma mitoses, stromal overgrowth, nuclear pleomorphism, fragmentation, adipose tissue infiltration, or other concerns
    • Cryoablation is also safe and effective

Usual ductal hyperplasia/florid ductal hyperplasia

• • Differentiate from mild ductal hyperplasia of the usual type - >70% of ductal lumen filled
  • Differentiate from ADH/DCIS - no atypia
  • Pathologic diagnosis - usually found as an incidental finding on a biopsy of mammographic abnormalities or breast masses
  • No treatment needed
  • Risk of subsequent breast cancer is small
  • Chemoprevention not indicated

Intraductal papilloma

• • Monotonous array of papillary cells growing from the wall of a cyst into its lumen - a true polyp, with both epithelial layer and myoepithelial layers around a fibrovascular stalk
  • Can harbour areas of atypia or DCIS
  • Can occur as solitary or multiple lesions
  • Solitary:
    • Frequently found as part of a workup for nipple discharge, especially bloody discharge - most common pathological cause. Thought to be from twisting/torsion of the papilloma.
    • Generally found close to areola
    • Mostly <1cm but can grow to 4 or 5cm
    • Excision warranted when a core biopsy demonstrates papilloma with atypical cells
      • Upgraded pathologically in 67% of cases
      • If no upgrading, worth discussing chemoprevention after excision
      • Excise through circumareolar incision
    • If no atypical cells demonstrated, bit unclear what to do, as upgrade rate to cancer on excision is probably <10%. Individualise decision based on size, symptoms, breast cancer risk factors. Probably leave alone.
    • If small incidental benign solitary papilloma with imaging concordance, appropriate to offer close clinical and radiological follow-up
  • Multiple: (diffuse papillomatosis)
    • Defined as a minimum of five papillomas within a localised segment of breast tissue, usually peripherally
    • Excise, preferably with oncoplastic techniques, as multiple future excisions may be required
    • Associated with a RR of developing cancer of 3.01 and 7.01, without and with atypia respectively

Stromal lesions

• • Sclerosing adenosis
    • Stromal fibrosis with myoepithelial proliferation
    • Presentation:
      • Palpable mass
      • Microcalcifications seen on screening mammogram (SA is the most common subsequent pathologic diagnosis on microcalcification CNB)
    • RR = 2
    • In the absence of atypia, no treatment is recommended
  • Radial scars/complex sclerosing lesions
    • Similar process of stromal fibrosis to sclerosing adenosis, but without the myoepithelial proliferation
    • Pathologic diagnosis
      • Radial scar if <1cm
      • CSL if >1cm
    • Occasionally big enough to be identified on mammography - appear similar to carcinomas because they create irregular spiculations in the surrounding stroma
    • Excision recommended - 8-17% show low-grade cancer/DCIS at excision
    • No treatment beyond excision. Risk of subsequent breast cancer is small, but there is a slight increase.

Adenomas

• • Pure epithelial neoplasms of the breast - sheet of glandular cells without supporting stroma
  • Distinguished from fibroadenomas by their sparse stromal elements
  • Tubular
    • Rare breast benign neoplasm of premenopausal women
    • Non-specific radiologic and cytologic features
    • Excision required to diagnose
  • Lactating
    • Occurs commonly in pregnancy
    • Well-circumscribed and lobulated
    • No malignant potential
    • Excision only indicated if large

Pseudoangiomatous stromal hyperplasia (PASH)

• • Benign stromal proliferation that histologically simulates a vascular lesion
  • May present as mass or thickening
  • Can be confused with mammary angiosarcoma
  • Excise if suspicious features on imaging, interval growth, or associated symptoms. But otherwise benign.
  • No increased risk of cancer.

Columnar cell hyperplasia

• • Change of cuboid epithelium to columnar in lobules
  • >2 cell layers
  • Observe provided no atypia

Proliferative with atypia/atypical hyperplasia (RR of lifetime breast cancer ~4-5x)

Atypical ductal hyperplasia

• • A proliferation of uniform epithelial cells, sharing the cytologic and architectural features of low-grade DCIS, but of limited extent
  • Must measure <2mm or involve <2 ducts
  • Usually diagnosed by core biopsy as the target lesion on the basis of mammographic microcalcifications
  • Management
    • Excision biopsy to exclude an associated malignant lesion (can result in upgrade to DCIS or invasive cancer)
    • Re-excision not indicated when ADH is present at the margin, unless a diagnosis of DCIS is near
  • RR for future breast cancer 3-5

Atypical lobular hyperplasia

• • ALH shares cytologic and architectural features with LCIS, but is quantitatively lesser in extent (filling, but not expanding, the involved lobule)
  • Usually an incidental finding on biopsies performed for other reasons
  • <3% risk of upgrading a core biopsy finding to DCIS or invasive cancer, and any upgrades are usually due to small, low-grade cancers
  • Radiologically-pathologically concordant ALH no longer requires excision
  • Excisional breast biopsy recommended for any discordant lesions
  • RR for future breast cancer 3-5

Flat epithelial atypia

• • Neoplastic alteration of the terminal duct lobular units characterised by replacement of the native epithelial cells (cuboid) by one to several layers of a single epithelial cell type (columnar) showing low-grade cytologic atypia
  • Related to columnar cell change and then columnar cell hyperplasia
  • RR of lifetime breast cancer only 1.5x
  • Excision. Upgraded to ADH/ALH/DCIS/LCIS 5-15%.

Miscellaneous

Lipoma

• • Excise if causing diagnostic confusion, continue to enlarge, or grow rapidly
  • No increased risk of breast cancer

Fat necrosis

• • Occurs with trauma or surgery or radiotherapy
  • Can mimic cancer on mammography by producing a palpable mass or density that may contain calcifications
  • Histologically - lipid-laden macrophages, scar tissue, and chronic inflammatory cells
  • No risk of cancer, does not need to be excised

Diabetic mastopathy

• • Aka lymphocytic mastitis or lymphocytic mathopathy
  • Seen in premenopausal women with longstanding T1DM
  • Dense, keloid-like fibrosis and periductal, lobular or perivascular lymphocytic infiltration
  • Maybe autoimmune reaction

Hamartoma

• • Benign
  • Discrete nodule that contains closely packed lobules and prominent, ectatic extra-lobular ducts
  • Indistinguishable clinically from fibroadenoma
  • Not increased risk of cancer per se, but because they don't have specific diagnostic features on biopsy or imaging, they might be excised if symptomatic or discordant findings

Sarcoidosis

• • Rare
  • Generally in the setting of systemic involvement
  • Feels like cancer clinically
  • No risk of subsequent cancer

Mondor's disease

• • Thrombophlebitis of a superficial vein
  • NSAIDs
  • Usually resolves

Congenital abnormalities

• Accessory breast tissue or accessory nipples
  • Failure of regression of the ectodermal ridge
  • Accessory nipples most commonly seen below the breast and above the level of umbilicus. Rarely cause problems, often not even noticed. Can be excised if causing irritation.

• Accessory tissue is usually seen in the axilla but occasionally below the breast. Often becomes more prominent during pregnancy and lactation. Can be excised, but the wounds and cosmesis can be challenging to manage.

• Absence of tissue
  • Can be associated with Poland's syndrome - a spectrum of conditions involving absence or hypoplasia of the pectoral muscle or breast, deformity of the underlying chest wall, and upper limb abnormalities. Rare, usually partial, more common in men.
  • Amastia
    • Congenital absence of the breast
    • Due to complete regression of the ectodermal ridge
  • Athelia
    • Congenital absence of the nipple
• Asymmetry of breasts
  • Common but usually mild, usually just requires reassurance
• Tubular breasts
  • Usually small, widely-spaced breasts with a high infra-mammary fold, narrow breast base and large areola
• Macromastia
  • Defined as breast weight >2-3% of body weight
  • Reduction mammoplasty after puberty - may recur if performed earlier