57. Mastitides (lactational, ductus ectasia, fat necrosis, galactocele). Mastopathies (fibrocystic change). Fibroepthelial tumours.

Functional unit of the breast?

Terminal duct lobular unit (TDLU)

Lobule + terminal duct that the lobule empties into

- Lobule produces milk

- Duct carries milk to nipple

Cell layers of ducts and lobules of the breast?

They all have two cell layers:

1. Luminal cell layer (faces lumen)

2. Myoepithelial layer

Why is TDLU significant?

It is from here the breast tumors originate from

Mastitis?

Inflammation of the breast

Associated with:

- Redness

- Edema

- Pain

- Tenderness

- Fever

May be infectious or non-infectious

Subtypes of mastitis?

- Lactational mastitis

- Mammary duct ectasia

- Fat necrosis

- Galactocoele

- Mastitis carcinomatosa

Lactational mastitis?

Milk stagnation in the breast -> due to lactating mothers cannot lactate enough; for various reasons

Allows for organisms to grow in the stagnated milk -> causing infection

- Staphylococcus aureus is the most common organism

How does bacteria enter the breast in lactational mastitis?

Bacteria enter the breast through fissures in the skin that develop during breastfeeding

Treatment lactational mastitis?

Symptomatic treatment:

- Painkillers

- Cold compresses

- Emptying of the breast regularly

- Antibiotics may be used

Mammary duct ectasia? "Plasma cell mastitis"

- Non-bacterial lymphoplasmacytic inflammation of the breast

- Occurs in older, non-breastfeeding women

Etiology&pathogenesis: unknown

- Ducts are dilated

How does mammary duct ectasia mimic cancer?

Breast secretions from the ducts into the periductal C.T. occurs -> a periareolar mass forms (mimics cancer)

This condition is harmless

There is green nipple discharge

Fat necrosis of the breast?

A non-bacterial, non-neoplastic condition that occurs after trauma to the breast

Firm mass is formed

- may mimic cancer

- The necrotic debris may calcify -> can be visualized on mammography

Galactocoele?

Milk-containing cyst in the breast

- Occurs in young, lactating women

Due to obstructed milk duct

- Importance: to distinguish it from cancer

Mastitis carcinomatosa?

Inflammatory breast carcinoma

- Type of breast cancer that manifests with an inflamed breast

Should be considered in patients with mastitis which does not resolve with antibiotic therapy

Fibrocystic changes of the breast?

Refers to multiple conditions where the TDLU is cystically dilated and fibrotic

- Happen in women in the reproductive age -> can be thought of as physiological aging (rarely cause problem)

Clinical relevance - fibrocystic changes of the breast?

They are not harmful themselves, but some may have increased risk for progressing into carcinoma

- If atypia is shown -> risk is even higher

Must be distinguished from cancer

Difference in fibrocystic changes of the breast and breast carcinoma?

Fibrocystic changes: myoepithelial cells are present -> these are not present in breast cancer

Types of fibrocystic changes of the breast?

• Non-proliferative pattern

• Proliferative pattern

- Epithelial hyperplasia

- Sclerosing adenosis

- Complex sclerosing lesion

are important...

Non-proliferative fibrocystic changes?

Most common of the two types

- Formation of cysts

- Increase in fibrous stroma

- No epithelial hyperplasia

Cysts range from <1cm to 5cm

They are typically blue -> "blue dome cysts"

Proliferative fibrocystic changes?

- Epithelial hyperplasia

- Sclerosing adenosis

- Complex sclerosing lesion

Epithelial hyperplasia - Proliferative fibrocystic changes?

Proliferative fibrocystic change, characterized by hyperplasia of the two epithelial layers of the TDLU

If there is atypia, it is called:

- Atypical ductal hyperplasia

or

- Atypical lobular hyperplasia

Depending whether the ducts of lobules are affected

What is epithelial hyperplasia of the breast a precursor for?

- DCIS

- LCIS

Sclerosing adenosis - Proliferative fibrocystic changes?

An increase in glands and stroma

- Glands will be compressed by the surrounding stroma

- May cause calcifications -> visualized on mammography

Complex sclerosing lesion - Proliferative fibrocystic changes?

Characterized by:

- A stellate architecture with prominent fibroelastosis and epithelial hyperplasia

Forms nodules that can cause skin retraction & palpable nodules

Should be removed - as they increase risk for malignancy

Fibroepithelial tumors?

- Fibroadenoma

- Phyllodes tumor

- Intraductal papilloma

Fibroadenoma?

Most common benign neoplasm of the breast

Comprised of:

- Neoplastic fibroblastic stroma and normal glands

Most frequent in 20-30y/age

Morphology fibroadenoma?

Firm, solitary, mobile, off-white well-circumscribed masses

Are not necessary to remove, as they are benign

Phyllodes tumor?

Similar to fibroadenoma

- However: their stromal component is more cellular

Phyllodes = "leaf-like" -> stroma often form leaflike projections

- Less common than fibroadenoma

- 75% are benign, rest is malignant

- Should be surgically removed

Intraductal papilloma?

Papillary growth that occurs inside dilated ducts

- More frequent in premenopausal women

- Lesions are less than 1cm, usually solitary

- Can cause bloody nipple discharge

Should be removed, as they can have malignant potential