Benign Breast Lesions and Clinical Presentations

Study Notes

Pathology of Benign Breast Lesions: Includes various types of cysts (Type I & II), papilloma, ductal hyperplasia, sclerosing adenosis, fibrocystic, and fibroadenoma. Visual aids (images) show examples of each.

Pain (Mastalgia): 95% of cases are benign.
Mass >2cm: Can be a cyst, fibroadenoma, or carcinoma.
Nipple Discharge: Can be bloody/serous (cyst, intraductal papilloma), or milky (galactorrhea, pituitary adenoma, hypothyroidism, anovulation).

Inflammation: Includes mastitis (acute and chronic forms). Chronic mastitis further breaks down to granulomatous, periductal, and plasma cell mastitis.
Galactocele: Obstructed mammary ducts resulting in a cyst filled with milky fluid, potentially secondary infection.
Fat Necrosis: Painless mass, skin thickening, or nipple retraction, mammographic density or calcifications are possible. Results from trauma or surgical procedures.
Benign Epithelial Lesions: Categorized as non-proliferative (fibrocystic changes), proliferative (without atypia-fibroadenosis, etc.), and proliferative (with atypia, a higher risk of developing cancer).

Acute Mastitis: Acute pyogenic infection, common in the first few weeks of breastfeeding (lactation). Mode of spread is often via nipple fissures.
Chronic Mastitis: Includes granulomatous, periductal, and plasma cell mastitis.
- Granulomatous mastitis: Linked to systemic diseases (sarcoidosis), foreign bodies (silicone implants), or infections (TB or fungi).
- Periductal mastitis: Smoking is a significant risk factor. Characterized by painful subareolar masses, duct dilation, rupture, and chronic/granulomatous inflammation.
- Plasma cell mastitis (mammary duct ectasia): NOT associated with smoking; it affects perimenopausal/multiparous women (ages 50-70). Symptoms include a painless mass, nipple discharge, and sometimes a lump.

Characteristics: Peri-areolar location; no association with smoking; usually affects multiparous women (50-70 years). Symptoms include a poorly defined painless mass, white nipple discharge, and thick, viscus nipple secretions.

Clinical Presentation: Painless mass, skin thickening, possible nipple retraction, mammographic density or calcification, linked to trauma/surgery
Histology: Hemorrhage and acute inflammation, leading to fat necrosis, followed by chronic inflammation with giant cells/hemosiderin and scar tissue, often with dystrophic calcification.

Risk Factor: Lactation
Pathogenesis: Obstruction and dilation of mammary ducts, forming a thin-walled cyst filled with milky fluid. Possible secondary infection

Fibrocystic Changes: Increased numbers of acini per lobule, with cystic and fibrous tissues often leading to a lumpy breast appearance. May include cysts with flat or apocrine metaplasia, fibrosis (ruptured cyst), and calcification.
Proliferative without Atypia: Includes sclerosing adenosis (increased acini per lobule), papillomas (epithelial growth with fibrovascular core, often causing nipple discharge), and complex sclerosing lesions (sclerosing adenosis + papillomas). Epithelial hyperplasia (layers of cells) is key, as are normal cytology and architecture.
Proliferative with Atypia: Atypical ductal hyperplasia (ADH) and atypical lobular hyperplasia (ALH) resemble carcinoma in situ, but are monomorphic (similar-looking) and lack atypical characteristics.

Stromal Origin: Fibroadenoma, Phyllodes (tumor origin from connective tissue)
Epithelial Origin: Duct papilloma (benign tumor in the milk ducts)

Description: A common benign breast tumor most common in women ages 15–30 during their reproductive years, characterized by a solitary, mobile, well-encapsulated nodule.
Histology: Circumscribed borders, low cellularity, and rare mitoses. Intracanalicular or pericanalicular patterns of fibrous overgrowth (and ducts).

Description: Uncommon, potentially aggressive breast tumor seen in women 30–70.
Gross Anatomy: Usually large (10–15 cm), round/oval, bosselated, with possible cystic areas, hemorrhages, necrosis, and degenerative changes.
Histology: Increased connective tissue (stromal) overgrowth with proliferating stromal cells covered by epithelium.
Behavior: Can range from benign to borderline to malignant; mitoses, atypia, cellularity, and infiltrative margins may highlight the aggressive nature of the tumor.

Description: Benign papillary tumor usually found near the nipple in milk duct areas.
Clinical Presentation: Serous or serosanguinous nipple discharge is a common symptom.
Gross Anatomy: Typically solitary, small (less than 1 cm).
Histology: Multiple papillae with well-developed fibrovascular stalks. Benign cuboidal epithelial cells supported by myoepithelial cells.