Types of benign tumours

Fibroadenoma

• Most common benign growth in the breast
• Usually occurs in women of reproductive age with peak incidence in 3rd decade but can occur at any age
• More common in Afro-Carribbean women
• Histology: proliferations of stromal and epithelial tissue of the duct lobules (biphasic)
• On examination, they are highly mobile lesions (historically termed a ‘breast mouse’) that are well-defined and rubbery on palpation, with most less than 5cm in diameter
• Have very low malignant potential, do not need to be removed because they tend to remain unchanged or decrease in size approaching the menopause (may be removed for comfort/cosmetic reasons - see management below)

Phyllodes tumour

• Rare fibroepithelial tumours which most commonly affects women 40-50 years
• Biphasic tumour dominated by stromal overgrowth
• They often grow rapidly
• Behaviour depends on stromal features - benign, borderline, malignant
  • Around one third of Phyllodes tumours have malignant potential - see notes on malignant phylodes tumour
  • Consequently, most Phyllodes tumours should be widely excised

Hamartoma (fibroadenolipomas)

• Circumscribed lesion composed of cell types normal to the breast but present in an abnormal proportion or distribution

Sclerosing lesions

• Benign, disorderly proliferation of acini and stroma
• Can cause a mass or calcification

Sclerosing adenosis

• Age 20-70