Pathology of the Breast

A. Disorders of Breast Development

1.       Supernumerary breasts or nipple- can be an extra breast or nipple anywhere in the “breast line” which extends from the axilla to groin

2.       Accessory axillary breast- breast tissue in the axilla

3.       Congenital inversion of nipple- congenital and can be surgically corrected because it presents as a problem during lactation.

4.       Macromastia- enlarged breast.  There is no “normal” size of a breast but this is when the breast is so enlarged that it causes problems such as back pain, that a breast reduction is desired.
 

B. Inflammatory Conditions

1. Acute and Granulomatous Mastitis - inflammation in the breast ductal system. Presents with pain and mass.
2. Duct ectasia- more common is older women.  It is a benign dilation of ducts that may cause discharge.
3. Fat necrosis- trauma will cause fat necrosis and lead to a mass (ie. will feel like a lump)
4. Silicone breast implants – silicone leaks and will cause a reaction that leads to fat necrosis.
    

C. Fibrocystic Change

Most common disorders (40% of breast pathologies). Cyst formation in the ductal system that will lead to a “lumpy bumpy breast.”  Grossly it will look blue on biopsy.  It is benign and has the following 3 changes.

a.       Cyst formation with aprocrine metaplasia

b.       Fibrosis

c.       Adenosis – increase in number of acini/lobules
 

D. Proliferative Breast Diseases

Proliferative Breast Diseases are clinically significant because there has been an increase in numbers of mammographic abnormalities and there are associated risks for breast carcinoma.  

1.       Epithelial hyperplasia - see multiple layers of luminal epithelium where there is an increase in the number of layers of duct epithelium from normal 2 layers (1 epithelium and 1 myoepithelium) to 4 or more layers. 

a.       Typical- proliferating cells appears as solid masses encroaching duct lumen and there is NO concern about it turning into something malignant.

b.       Atypical- ductal cells proliferate more and fill the lumen and cells appear to be more monotonous, which is a sign that it can become malignant.

c.       Atypical lobular hyperplasia-  acinar cell proliferation

2.       Sclerosing adenosis- Increased number of distorted and compressed acini. 

a.       Commonly presents as a calcification on mammography

b.       Myoepithelial cells are preserved and increased. 

c.       Sclerosing can mimic cancer proliferation

Sclerosis is a syn for induration “A focus or region of indurated (firm or hard) tissue” (Stedman’s online)

3.       Small duct papillomas - small projections into duct. Can be differentiated microscopically
 
 

Risks for breast carcinoma

1.       No risk- adenosis, fibrocystic changes, mild duct hyperplasia

2.       1.5-2 times risk- sclerosing adenosis, moderate to florid epithelial hyperplasia, papilloma  (Proliferative diseases)

3.       4-5 times risk- atypical hyperplasia (ductal and lobular)

4.       Family History of breast cancerà all categories are at risk

 

Male Breast Diseases

1. Gynecomastia

• Unilateral or bilateral
• Sub-areolar enlargement
• Dense periductal hyaline and collagenous connective tissue and hyperplasia of duct epithelium.
• No lobules in males
• Can be caused by

1.       Hormonal imbalance

2.       Klinefelter’s syndrome (XXY)

3.       Testicular neoplasms

4.       cirrhosis of liver

5.       drugs (alcohol, marijuana, heroin, anabolic steroids)

2. Carcinoma of male breast

·         Rare with a frequency ratio to female breast cancer of less than 1:100

·         Risk factors similar to females

·         Associated BRCA 2

·         DCIS and LCIS rare, almost always invasive cancers.

·         Histological subtypes similar to females

·         Estrogen receptors are usually present

·         Prognostic factors same and matched by stage.

Back to the Reproductive System Index