- is common breast disorder
- common between 25 and 50 years of age
Pathogenesis:
1- Estrogen & Progesterone:
Estrogen predominance over progesterone is considered causative
2- Others: i- Prolactin: levels are increased in 1/3 of women with FCC ii- Thyroid hormones: sensitize mammary epithelium to Prolactin stimulation

Morphology:
- morphologically divided into 3 groups:
1- Nonproliferative change
2- Proliferative change without atypia
3- Proliferative change with atypia
1- Nonproliferative change:
- not associated with risk of breast cancer
- 3 forms: 1- cyst
2- fibrosis
3- adenosis
1) Cysts:
- formed by dilatation of lobules
- may cause breast lumpiness, nipple discharge
2) Fibrosis :
- cysts frequently ruptured, release their content into stroma leads to chronic inflammation and fibrosis

3) Adenosis :
- is an increase in the number of acini (tubules) per lobule
- either : - physiological, during pregnancy (diffuse change)
- pathological , in nonpregnant (focal change)
C

2- Proliferative change without atypia :
- characterized by proliferation of ducts and lobules epithelium and or stroma without atypia
1) epithelial hyperplasia
2) sclerosing adenosis ( adenosis with dense fibrous stroma , mistaken for cancer )
3) Intraductal papilloma :
- occurs in large lactiferous ducts
- clinically may cause serous or bloody discharge

3- Proliferative change with atypia :
- includes atypical ductal hyperplasia (ADH) and atypical lobular hyperplasia (ALH)
- there is proliferation of epithelium with atypical changes
- ADH is more common than ALH
- both predispose to carcinoma

Clinical features:
- discovered incidentally (mammography)
- present as palpable mass
- nipple discharge, serous, bloody,… (cyst, intraductal papilloma)
Investigations:
1- mammography
2- ultrasonography
3- FNA and histopathology

- is the most common breast tumor
- may occur at any age, common before 30
- it is hormone responsive (increase in size during cycle)
Morphology:
- single or multiple, small or large
- usually unilateral but may be bilateral
- Grossly: firm, white or gray, well-circumscribed mass
- Micro: cellular stroma enclosing the acini or glands:
1- in slit-like spaces (intracanalicular)
2- glands retain rounded shape (pericanalicular)
C/F: - palpable mass
- FNA, histopathology, mammography
- surgical excision

(giant fibroadenoma )
- is uncommon
- in middle-aged or elderly women, rare before 40 years
Morphology:
- Grossly: huge, lobulated, circumscribed mass
- Micro: cleft-like or cystic spaces lined by epithelium with cellular stroma
C/F:
- huge lobulated mass
- FNA, histopathology, mammography
- Complete excision is curative
- 10% recurrence (incomplete excision)
- malignant change occurs in < 5% of cases (sarcoma)