Breast: Normal Histology and Benign Diseases Flashcards
(37 cards)
Breast tissue
- dense fibrous tissue
- contains smooth muscle fibers that assist with milk expression
- the areola is more pigmented than the rest of the skin and becomes more so during pregnancy
Lymphatic drainage of the breast
-to axillary, supraclavicular, and mediastinal lymph node
Duct system of the breast
- breast contains 6-10 major ductal systems
- keratinizing squamous epithelium of the overlying skin dips into the orifices at the nipple and then abruptly changes to a double-layered cuboidal epithelium lining the ducts
- branching of large ducts leads to terminal duct lobular unit (functional unit of breast)
- terminal duct branches into a grapelike cluster of small acini (tubules) to form a lobule
Two cell types that line ducts and lobules
- Contractile myoepithelial cells (MEC)– assist in milk ejection
MEC layer is lost in invasive breast cancer
- luminal epithelial cells overlay the myoepithelial cells. Milk production.
Two types of breast stroma
- interlobular stroma: dense fibrous CT mixed with adipose tissue
- intralobular stroma envelopes the acini of the lobules and consists of breast-specific hormonally responsive fibroblast-like cells mixed with scattered lymphocytes
How does the male breast differ from female?
no tubules (acini) -made of ductal structures surrounded by small amount of adipose and fibrous tissue
Breast structure during childhood, before puberty
female breast is composed of branching ductal system without the lobular units.
Changes at puberty
- estrogen and progesterone lead to proliferation of glandular tissues
- once formed, lactiferous ducts and interlobular duct system are stable
- TDLUs are dynamic and undergo changes with alterations of hormone levels (changes involve epithelium and intralobular stroma)
Changes during the menstrual cycle
First half: lobules = quiescent
After ovulation, under the influence of estrogen and rising progesterone levels, cell proliferation increases, as does the number of acini per lobule. The intralobular stroma also becomes markedly edematous
With menstruation, the fall in estrogen and progesterone levels induces the regression of the lobules and the disappearance of the stromal edema
Changes in pregnancy
-the breast become completely mature and functional. Lobules increase progressively in number and size. As a consequence, by the end of the pregnancy the breast is composed almost entirely of lobules separated by relatively scant stroma
After delivery:
luminal cells of the lobules produce colostrum (high in protein), which changes to milk (higher in fat and calories) over the next 10 days as progesterone levels drop.
Changes with cessation of lactation
With cessation of lactation, the breast epithelium and stroma undergo extensive remodeling. Epithelial cells undergo apoptosis, lobules regress and atrophy, and the total breast size is diminished. However, full regression does not occur, and as a result pregnancy causes a permanent increase in the size and number of lobules.
Changes with menopause
With increasing age, lobules and their specialized stroma start to involute. Lobular atrophy may be almost complete in elderly females.
The interlobular stroma also changes, since the radiodense fibrous stroma of the young female is progressively replaced by radiolucent adipose tissue.
Accessory breasts or nipples
May occur anywhere along embryonic mammary ridges. Accessory nipple may be seen just below the normal breast . Accessory or ectopic breast tissue may be seen in the lower axilla where it may raise a concern for metastatic cancer.
Congenital inverted nipples
clinically significant as similar change may be produced by underlying cancer.
Juvenile hypertroph
- rare
- adolescent girls
- breasts (one or both) markedly enlarge due to hormonal stim
- no endocrine abnormality
- embarrassment, pain, discomfort
- reduction mammoplasty improves QoL
Gynecomastia
Enlargement of one or both breasts in a male. Many cases are idiopathic. Some may be caused by excessive estrogen stimulation. Predisposing factors include:
•hormonal imbalance, as may occur in puberty or old age
•exogenous hormones
•drugs, including dilantin, digitalis, marijuana
•Klinefelter’s syndrome (testicular feminization)
•testicular tumors
•liver disease
Microscopic features of gynecomastia are ductal epithelial hyperplasia, stromal edema, and loose fibrosis around ducts.
Acute mastitis and breast abscesses
Acute inflammation of the breast, often with abscess formation, occurs commonly at the onset of lactation (puerperal mastitis)
- cracks in nipple and milk stasis predispose to infection
- Staph aureus most common
- redness, swelling, pain, and tenderness in the affected area of the breast.
- Abscess formation is common and requires drainage of pus.
Differential diagnosis includes inflammatory breast carcinoma
Chronic mastitis
- rarer
- perimenopausal women (due to obstruction of the lactiferous ducts by inspissated luminal secretions)
- Obstruction leads to dilatation of the ducts (mammary duct ectasia) and periductal chronic inflammation
- usually plasma cells (plasma cell mastitis)
- rarely includes foamy histiocytes and fibrosis (granulomatous mastitis)
- both types produce irregular masses with induration that mimic breast carcinoma
periductal mastitis
-F and M (rare)
-painful erythematous subareolar mass that clinically appears to be an infectious process
-90% are smokers
-In recurrent cases, a fistula tract often tunnels under the smooth muscle of the nipple and opens onto the skin at the edge of the areola
-many women have inverted nipple
-Why with smoking?
Possibly: Vit A deficiency or toxic substances alter the differentiation of the ductal epithelium
Fat necrosis
uncommon disease of unknown cause
- possible ischemia from stretching and narrowing of arteries in pendulous breasts
- early phase: collection of neutrophils and histiocytes around necrotic fat cells
- later: fibrosis, calcification
*clinical importance is that this may present as a hard mass that can be suspicious for carcinoma on physical examination
Fibroadenoma
- Benign neoplasm found often in young women but may occur at any age
- solitary, discrete, mobile mass composed of proliferating ducts (“adenoma”) in proliferating fibroblastic stroma (“fibro”).
- risk for development of breast cancer relates to presence/absence of complex features
- tx: surgical excision
Lactating adenoma
- palpable mass in pregnant or lactating women.
- It is formed by normal-appearing breast tissue with physiologic adenosis and lactational changes
- may be assoc w/ rapid increase in size during pregnancy, raising suspicion of carcinoma
likely not true neoplasms, but exaggerated response to hormonal influences
Intraductal papilloma
benign neoplasms
- commonly originating in a major lactiferous duct near the nipple.
- present with a bloody nipple discharge.
- Most = about 1 cm in diameter.
- The large tumors are palpable as a subareolar mass.
- Grossly, the tumor appears as a papillary mass projecting into the lumen of a large duct.
- Histologically, there are numerous delicate papillae composed of a fibrovascular core, covered by a layer of epithelial and myoepithelial cells.
- In complex papillomas, distinction from papillary carcinoma may be difficult.
Phyllodes tumor
- Rare tumors composed of intralobular stroma and ductal epithelium
- benign (most) to malignant
- cured by excision
- low grade can recur after excision
- high grade malignant can metastasize
- most grow to massive size
- cut section: leaf-like clefts and slits
- micro: benign epithelium overlying a stromal over growth. Benign ones have no cytologic atypia or mitoses
