Breast pathology

Question 1

Acute mastitis

Answer 1

• Bacterial infection of breast
• Usually due to S. aureus
• Associated with breast-feeding (lesions cause opening for the bacteria into duct through nipple)
• Presentation: warm, erythematous breast with purulent nipple discharge
• Treatment: continued drainage and antibiotics

Question 2

Periductal mastitis

Answer 2

• Inflammation of subareolar ducts (block in end of duct - inflammation proximal to the block)
• Usually seen in smokers (due to vit. A deficiency)
  Presentation: subareolar mass with nipple retraction

Question 3

Mammary duct ectasia

Answer 3

• Inflammation with dilation (ectasia) of subareolar ducts
• Rare
• Classically arises in multiparous postmenopausal women
• Presentation: perialeolar mass with green-brown nipple discharge
• Chronic inflammation with plasma cells is seen on biopsy

Question 4

Fat necrosi

Answer 4

• Necrosis of breast fat
• Usually related to trauma
• Presents as a mass on exam or calcification on mammography
• Biopsy shows necrotic fat with associated calcifications and giant cells

Question 5

Fibrocystic disease

Answer 5

• Most common disorder of the breast
• Development of fibrosis and cysts
• Presents as lumpy breast, usually in upper outer quadrant
• Postulated to result from increased activity of, or sensitivity to, estrogen or to decrease progesterone activity
• Cysts have blue-domed appearance on gross
• Benign, some changes carry increased risk for invasive carcinoma:
• Fibrosis, cysts, and apocrine metaplasia
• Ductal hyperplasia and sclerosing adenosis (2x increase in cancer risk)
• Atypical hyperplasia (5x)

Question 6

Fibroadenoma

Answer 6

• Most common breast tumor in women younger than 25 years of age
• Tumor of fibrous tissue and glands
• Entirely benign and is not a precursor of breast cancer
• Well-circumscribed, mobile marble-like mass
• Estrogen sensitive
  (1) Intracanalicular fibroadenoma
  (2) Pericanalicular fibroadenoma

Question 7

Phyllodes tumor

Answer 7

• Fibroadenoma-like tumor with overgrowth of fibrous component
• Large, bulky mass of variable malignancy with ulceration of overlying skin
• Characteristically contain leaflike projections from the cyst walls and myxoid contents

Question 8

Intraductal pipilloma

Answer 8

• Papillary growth, usually into large duct
• Fibrovascular projections lined by epithelial and myoepithelial cells
• Bloody nipple discharge in a premenopausal woman
• Must distinguish from papillary carcinoma (no myoepithelial cells in carcinoma)

Question 9

Ductal carcinoma in situ (DCIS)

Answer 9

• Malignant proliferation of cells in duct
• No invasion of basement membrane
• Detected as calcification on mammography
• Comedo type has high-grade cells with necrosis and dystrophic calcification in center of ducts

Question 10

Paget disease

Answer 10

• DCIS that extends up ducts to skin of nipple
• Presents as nipple ulceration and erythemia
• Almost always associated with an underlying carcinoma

Question 11

Invasive ductal carcinoma

Answer 11

• Most common type of invasive carcinoma
• Classically forms duct-like structures
• Presents as mass detected by physical exam or mammography
• Advanced tumors may result in dimpling of skin or retraction of nipple
• Biopsy: duct-like structures in desmoplastic stroma
• Special subtypes: tubular carcinoma, mucinous carcionoma, medullary carcinoma, inflammatory carcinoma
• Graded using the Bloom-Richardson system

Question 12

Lobular carcinoma in situ (LCIS)

Answer 12

• Malignant proliferation of cells in lobules
• No invasion of basement membrane
• Discovered incidentally; does not produce mass or calcification
• Dyscohesive cells lacking E-cadherin
• Often multifocal and bilateral
• Treatment: tamoxifen and close-follow up. Low risk of progression to invasive carcinoma

Question 13

Invasive lobular carcinoma

Answer 13

• Less common than IDC
• Grows in single-file pattern
• No duct formation due to lack of E-cadherin