Benign Breast Histology

Question 1

Describe the lining of mammary ducts.

Answer 1

Mammary ducts are lined by 2 layers of cells:

• One layer of secretory epithelial cells
• One layer of myoepithelial cells

Question 2

Compare intralobular v interlobular response to hormones

Answer 2

Intralobular stroma is responsive to hormones

Interlobular stroma is not

Question 3

When do mammary gland acini develop?

Answer 3

Puberty

Question 4

Name one change that occurs to the breast tissue after menopause

Answer 4

Fat replaces stroma/fibrous tissue

Question 5

What causes gynecomastia?

Name 3 time periods in which it may be normal

Answer 5

Relative increase in estrogen (compared to androgens)

Can be normal in neonates, puberty, or elderly

Question 6

What is the pathogenesis of acute mastitis?

What is the typical pathogen?

Answer 6

• Cracks in nipple occur during breastfeeding -> bacterial infection
• Staph aureus most common

Question 7

Tx of lactational mastitis (2)

Answer 7

Antibiotics

Continue breastfeeding

Question 8

What causes fat necrosis?

How does it typically present

Answer 8

• Due to injury to breast tissue
• Hard, irregular, painless mass

Question 9

What age group gets fibroadenomas?

How does this affect cancer risk?

Answer 9

• Women under 35 yo
• Fibroadenomas do not increase cancer risk

Question 10

What age group gets Phyllodes tumor?

How does this affect cancer risk?

Answer 10

• Women in 40s
• Extremely variable cancer risk - may be totally benign or progress to high grade cancer

Question 11

How does Phyllodes tumor get its name?

Answer 11

Phyllodes = leaf in greek

Tumor looks “leaf-like”

Question 12

Name one benign cause of bloody nipple discharge.

How does this process affect cancer risk?

Answer 12

Intraductal papilloma

Slight increase in cancer risk

Question 13

Name 4 drugs that cause gynecomastia

Answer 13

1. Spironolactone
2. Cimetidine
3. Finasteride
4. Ketoconazole

Question 14

Describe the mammogram and biopsy of fat necrosis

Answer 14

• Mammogram: calcified, oil cyst
• Biopsy: necrotic fat, giant cells

Question 15

What benign breast tumor is responsive to estrogen?

Answer 15

Fibroadenomas

(they grow and increase in tenderness with estrogen)

Question 16

What is an intraductal papilloma?

Answer 16

Fibro/epithelial tumor within the lactiferous duct

Question 17

What age group gets fibrocystic changes?

How does it present?

Answer 17

Women under 35 yo

Can present with premenstrual breast pain or lumps

Question 18

What is sclerosing adenosis?

How does it affect cancer risk?

Answer 18

• Acini and stromal fibrosis, with calcification
• Slight increase in cancer risk

Question 19

Name 2 non-malignant pathologies that affect the lactiferous and major ducts

Answer 19

• Intraductal papilloma
• Mastitis

Question 20

Name 1 benign disease of the terminal duct/lobular epithelium

Name 2 benign diseases of the terminal duct/lobular stroma

Answer 20

• Terminal duct epithelium: fibrocystic change
• Terminal duct stroma: fibroadenoma, Phyllodes tumor

Question 21

What is a ductal carcinoma in situ?

How does it appear on mammogram?

Answer 21

• Carcinoma filling the ductal lumen (no invasion of basement membrane)
• Appears as microcalcifications

Question 22

True or false:

Bloody nipple discharge is associated only with cancerous conditions.

Answer 22

False.

Both carcinoma and papilloma can display blood discharge

Question 23

Which of these is considered a fibrocystic change?

• Ductal hyperplasia
• Cysts
• Apocrine metaplasia

Answer 23

All of them!

Question 24

What is the most common benign breast tumor?

Answer 24

Fibroadenoma