This document summarizes the pathology of the breast, including normal anatomy, developmental abnormalities, benign and malignant tumors, and carcinoma. It describes the ducts, lobules, and stroma that make up normal breast tissue. It also discusses ectopic breast tissue, inflammatory conditions like fat necrosis and granulomatous lobular mastitis, benign proliferative lesions including fibrocystic changes and hyperplasias. Common benign tumors mentioned are fibroadenomas and phyllodes tumors. Malignant tumors discussed in detail are ductal carcinoma, lobular carcinoma, and invasive carcinomas. Pathology of the male breast including gynecomastia and rare breast cancer is also summarized.

1. Pathology of the breast
• normal anatomy
•developmental abnormalities
•inflammations
• fibrocystic changes
• tumors
• benign
• malignant
• pathology of the male breast

2. Normal anatomy
•Epithelium:
•Ducts
•Lobules
•Stroma:
•Interlobular
•Lobular

3. Ectopic breast
• supernumerary breast
along the milk lines
Developmental abnormalities

4. Inflammatory and reactive
conditions
Fat necrosis
• can form mass clinically
• history of trauma or prior surgical intervention)
• histiocytes with foamy cytoplasm

5. Inflammatory and reactive
conditions
Granulomatous Lobular Mastitis
• etiology unknown
Mammary duct ectasia
• periductal inflammation, duct sclerosis
• intermittent nipple discharge
Tuberculosis
•lactating breast, innoculation via the lactiferous ducts
• slowly growing, solitary, painless mass

6. Benign proliferative lesions
Fibrocystic changes:
• Fibrosis, cysts, Apocrine change and papillae
Hyperplasia:
• ductal and lobular hyperplasia
• atypical ductal and lobular hyperplasia

7. Benign tumors
Fibroadenoma
• proliferation of epithelial and stromal elements
• most common breast tumor in adolescent and young
adult women (peak age = third decade)
•well-circumscribed, freely movable, nonpainful mass
• ducts distorted into slit-like structures
Tubular adenoma
Lactating Adenoma

8. Cystosarcoma phyllodes
(phyllodes tumor)
•fleshy tumor, leaf-like pattern and cysts on cut surface
•benign, malignant (low grade, high grade)

9. Breast carcinoma
• most frequent malignant tumor in
females
•risk factors: genetic predisposition
(breast ca in close/ 1st
degree relatives),
history of ca (breast, ovary,
endometrium)
• importance of preventive controls! –
early diagnosis better prognosis

10. Breast carcinoma -
classification
Ductal carcinoma
• Insitu
• Invasive
Lobular carcinoma
• Insitu
• Invasive

11. Carcinoma in situ
• preinvasive - does not form a palpable tumor
• not detected clinically (only X-ray – screening !!!)
•no metastatic spread (basement membrane)
• risk of invasion depending on grade

12. Invasive carcinoma
Invasive ductal carcinoma
• largest group (65 to 80 % of mammary carcinomas)
• mid to late fifties
Invasive lobular carcinoma
• uniform cells, infiltrative growth (linear arrangement -
indian file pattern)

13. • other types: tubular, mucinous, medullary,
inflammatory – together about 10 % of breast ca
• metastases: regional lymph nodes
• treatment: surgery
radiotherapy
antihormonal therapy (Tamoxifen)
chemotherapy
Invasive carcinoma

14. Pathology of the male breast
Gynecomastia
• most common clinical and pathologic abnormality of the
male breast
• increase in subareolar tissue
• associated with decreased androgens or increased
estrogen: cirrhosis of the liver, chronic renal failure and hypogonadism
Carcinoma of the male breast
• uncommon < 1 % of all breast cancers