Breast Pathology Flashcards
Embryology of Breast
modified sweat gland, derived form the skin
breast tissue can develop anywhere along the milk line, which runs from axilla to vulva
lubules and ducts are lined by how many laters of epithelium?
Two layers:
Luminal cell layer - inner cell layer lining the ducts and lobules; responsible for milk production in the lobules
myoepithelial cell layer - outer cell layer lining ducts and lobules; contractile function propels milk towards the nipple.
During pregnancy, what promotes the breast lobules to undergo hyperplasia?
Hyperplasia is driven by estrogen and progesterone produced by the corpus luteum (early first trimester), fetus, and placenta (later in pregnancy)
galactorrhea
milk production outside of lactation
not a symptom of breast cancer
causes include nipple stimulation (common physiologic cause), prolactinoma of the anterior pituitary (common pathologic cause), and drugs
acute mastitis
bacterial infection of the breast, usually due to Staph aureus
associated with breast-feeding; fissures develop - route of entry for microbe
present as erythematous breast with purulent nipple discharge; may progress to abscess formation
periductal mastitis
inflammation of the subareolar ducts
seen in smokers
vitamin A deficiency results in squamous metaplasia of lactiferous ducts, producing duct blockage and inflammation
clinically presents as a subareolar mass with nipple retraction
mammary duct ectasia
inflammation with dilation (ectasia) of the aubareolar ducts
RARE, arises in multiparous postmenopausal women
Presents as a periareolar mass with green-brown nipple discharge (inflammatory debris)
chronic inflammation with plasma cells seen on biopsy
Fat necrosis
necrosis of breast fat
related to trauma
presents as a mass on physical exam or abnormal calcification on mammography (due to saponification)
biopsy shows necrotic fat with associated calcifications and giant cells
What is the gross appearance of breast cysts?
blue-dome
What is the risk for invasive carcinoma when there is a presence of fibrosis, cysts, and apocrine metaplasia?
no increased risk
What is the risk for invasive carcinoma when there is a presence of ductal hyperplasia and sclerosing adenosis?
2x increased risk
What is the risk for invasive carcinoma when there is a presence of atypical hyperplasia?
5x increased risk
Intraductal papilloma
papillary growth into large duct
fibrovascular projections lined by epithelial (luminal) and myoepithelial cells
Presents as bloody nipple discharge in premenopausal women
Papillary carcinoma
fibrovascular projections lined by epithelial cells without underlying myoepithelial cells
presents as bloody nipple discharge
risk of papillary carcinoma increases with age thus, more commonly seen in postmenopausal women
Fibroadenoma
tumor of fibrous tissue and glands
presents as a well-circumscribed, mobile marble-like mass
estrogen sensitive-grows during pregnancy and may be painful during the menstrual cycle
benign, with no increased risk of carcinoma
Phyllodes tumor
fibroadenoma-like tumor with overgrowth of the fibrous component; characteristic ‘leaf-like’ projections are seen on biopsy
commonly seen in postmenopausal women
malignant in some cases
What are risk factors for breast cancer?
estrogen exposure:
age- cancer usually arises in postmenopausal women
early menarche/late menopause
obesity
atypical hyperplasia
first-degree relative (mother, sister, or daughter) with breast cancer
Ductal carcinoma in situ
malignant proliferation of cells in ducts with no invasion of the basement membrane
often detected as calcification on mammography; DCIS does not usually produce a mass
histologic subtypes are based on architecture; comedo type is characterized by high-grade cells with necrosis and dystrophic calcification in the center of ducts
Paget disease
DCIS that extends up the ducts to involve the skin of the nipple
Presents as nipple ulceration and erythema
Almost always associated with an underlying carcinoma
invasive ductal carcinoma
classically forms duct-like structures
most common type of invasive carcinoma in the breast, accounting for >80% of cases
presents as a mass detected by physical exam or by mammography - advanced tumors may result in dimpling of the skin or retraction of the nipple.
Biopsy usually shows duct-like structures in a desmoplastic stroma
Special subtype of invasive ductal carcinoma:
Tubular carcinoma
characterized by well-differentiated tubules that lack myoepithelial cells; relatively good prognosis
Special subtype of invasive ductal carcinoma: Mucinous carcinoma
characterized by carcinoma with abundant extracellular mucin (‘tumor cells floating in a mucus pool’)
tend to occur in older women
relatively good prognosis
Special subtype of invasive ductal carcinoma:
Medullary carcinoma
characterized by large, high-grade cells growing in sheet with associated lymphocytes and plasma cells
grows as well-circumscribed mass that can mimic fibroadenoma on mammography
relatively good prognosis
increased incidence in BRCA1 carriers
Special subtype of invasive ductal carcinoma: Inflammatory carcinoma
Carcinoma in dermal lymphatics
presents classically as an inflamed, swollen breast (tumor cells block drainage of lymphatics) with no discrete mass; can be mistaken for acute mastitis
poor prognosis
