Breast: Normal Histology Benign Disease Flashcards
Basic anatomy of breast + lymphatic drainage
- The breast contains 6-10 major ductal systems.
- Males have ducts but no acini (nor do girls before puberty)
- Lymphatic drainage of the breast: axillary, supraclavicular & mediastinal lymph nodes
- Cancer is most common in the upper outer quadrant of the breast, which generally drains to the axillary nodes, which is why the axillary nodes are commonly the sentinel nodes for metastasis.
What is the terminal duct-lobular unit, (TDLU)?
TDLU: terminal duct (smallest duct division) and the surrounding acini that drain into it. Functional unit of the breast.
Histology of epithelial components of breasts
- Epithelial Components: 2 types of breast epithelium:
- Keratinizing squamous epthielium
- Most superficial layer which “dips into the orifices at the nipple”
- Becomes the double-layer cubiodal epithelium
- Double-layered cuboidal epithelium line the ducts (columnar)
- 2 cell types:
- Myoepithelial cells (MEC)
- Luminal epithelial cells
- more than two cell layers = abnormal.
- Vacuolization of the cuboidal cells = filling with milk.
- 2 cell types:
Histology of stromal components of breasts
- Stromal components: 2 types of breast stroma
- Interlobular stroma → dense fibrous connective tissue admixed with adipose tissue
- Intralobular stroma → envelopes acini of the lobules
- Contain hormonally responsive fibroblast-like cells admixed with lymphocytes
Histologic appearance of resting breast
*as previously described*
Histologic appearance of breast during pregnancy/lactation
- Maximum stimulation, epithelial
- vacuolization, secretion in lumina
- Pregnancy → ↑ terminal ducts
- (lobules)
- Lactation → ↑ acini draining to
- terminal ducts
Histologic appearance of post-emnopausal breast
Involution of TDLUs, acini atrophy Duct system remains
↑ interlobular fat & stroma
↓ intralobular fat & stroma
Basic breast-related changes throughout life
- Puberty → stimulation by E and P
- Menstrual cycle → ↑ size/nodularity; luteal phase → ↑ tubules + acini
- Pregnancy/lactation → maximum stimulation, epithelial vacuolization, secretion in lumina
- Cessation of lactation → involution in 3 months
- Post-lactation → ↓ lobules but overall there remains a permanent ↑ in size + number of lobules compared to pre-pregnancy
Congenital anomalies of breasts
- supernumerary nipple / breasts
- accessory breast tissue
- congenital inversion of nipples
Characteristics of supernumerary nipples/breasts
- Supernumerary (extra) nipple/breast = accessory breasts or nipples
- During development human females get early breast development all the way down the sides of the anterior torso. These generally are reasorbed, but occasionally some of the tissue remains.
- This can cause some worries → ie., a growing lump in the axilla during pregnancy.
- Fine needle biopsy can distinguish ectopic breast tissue from cancer.
- People with an inherited tendency towards breast cancer can get breast cancer in odd locations, as well.
Characteristics of congenital nipple retraction/inversion
Can be unilateral or bilateral, is generally normal.
Acquired nipple inversion, by contrast, is often a late sign of breast cancer.
Characteristics of hypertrophy of breast tissue
Juvenile hypertrophy (virginal hypertrophy): super-normal increase in size of the breasts, usually during puberty
Can be unilateral or bilateral.
Rare
Etiology unclear.
Often treated with breast reduction surgery.
Characteristics of gynecomastia
Gynecomastia → Enlargement of one or both breast in a male
Most common benign lesion in men
On histology you see large duct structures and lots of interlobular stroma.
Many cases idiopathic but can be due to an increase in estrogen.
Most often occurs at puberty and is self-limited; can be due to drug use.
Types of benign inflammatory breast lesions
- acute mastitis and abscess
- chronic mastitis
- mammary duct ectasia
- plasma cell mastitis
- granulomatous mastitis
- periductal mastitis
- fat necrosis
Characteristics of Acute mastitis/abscess
- Acute inflammation of the breast, often with abscess. Often young women at onset of lactation
- Painful, tender. Due to cracking of skin that allows entry of bacteria → Staph a.
- If untreated abscesses can cause fistulas with the skin.
- Differential dx: inflammatory carcinoma
- Rx: antibiotics, drainage of pus
- If doesn’t respond to antibiotics get a biopsy