8. Benign tumors of the mammary gland; precancerosis

BREAST ANATOMY AND ASSESSMENT

• The breast extends from the second to sixth ribs and from the sternal edge towards the mid-axillary line, with an axillary tail.
• It contains lobules, ducts, fibrous stroma and adipose tissue.
• Lymph drains mainly to axillary nodes, with internal mammary and supraclavicular pathways.
• Clinical assessment uses triple assessment: history/examination, imaging and tissue diagnosis when indicated.
• A new lump should not be assumed benign based on age alone.

BENIGN LESIONS

• Fibroadenoma is a common benign fibroepithelial tumour, often mobile, firm and well circumscribed in younger patients.
• Phyllodes tumours are fibroepithelial lesions that may grow rapidly and can be benign, borderline or malignant; wide excision with clear margins is important.
• Breast cysts are common, may be simple or complicated, and can be painful.
• Intraductal papilloma may cause spontaneous unilateral bloody or serous nipple discharge.
• Duct ectasia causes dilated subareolar ducts and sticky discharge or nipple retraction.
• Fat necrosis can follow trauma or surgery and may mimic carcinoma.
• Mastalgia may be cyclical or non-cyclical and requires assessment for a focal lesion.