B15. Benign breast tumors and inflammatory diseases of the mammary gland
There exist multiple types of benign tumours of the breast. Some have potential to progress into breast cancer, some don't.
Treatment
Surgical removal is indicated for:
- Intraductal papilloma with atypia
- Complex sclerosing lesions
- Complex fibroadenomas with suspicious histological features
- Phyllodes tumour
Fibrocystic changes
Fibrocystic changes in the breast refers to multiple conditions where the terminal duct lobular unit is cystically dilated and fibrotic. These changes happen in women in the reproductive age and can even be thought of as part of physiological aging as they rarely cause problems. These changes are benign in themselves, but some may have an increased risk for progressing into carcinoma. If the change shows atypia the risk is even higher.
These changes are clinically relevant as they must be distinguished from breast cancer. In fibrocystic changes myoepithelial cells are present, unlike in breast cancer.
Fibrocystic changes are divided into non-proliferative and proliferative patterns. Of the latter group epithelial hyperplasia, sclerosing adenosis and complex sclerosing lesion are important.
Non-proliferative fibrocystic changes
Non-proliferative fibrocystic changes are the most common of the two types. There is formation of cysts and an increase in fibrous stroma. There is no epithelial hyperplasia. The cysts range from < 1 cm to 5 cm in diameter. They are typically blue, hence the nickname “blue dome cysts”.
Proliferative fibrocystic changes
Epithelial hyperplasia is a proliferative fibrocystic change characterised by hyperplasia of the two epithelial layers of the terminal duct lobular units. If there is atypia the condition is called atypical ductal hyperplasia (ADH) or atypical lobular hyperplasia (ALH), depending on whether the ducts or lobules are affected. These conditions are precursors for DCIS and LCIS, described in the next topic.
Sclerosing adenosis is a proliferative fibrocystic change characterised by an increase in glands and stroma. The glands are compressed by the surrounding stroma. These changes may cause calcifications, which can be visualized on mammography.
Complex sclerosing lesion is a proliferative fibrocystic change characterised by a stellate architecture with prominent fibroelastosis and epithelial hyperplasia. It forms nodules that can cause skin retraction and palpable nodules. These should be removed due to an increased risk of malignancy.
Fibroepithelial tumors
Fibroadenoma
Fibroadenoma is the most common benign neoplasm of the breast. They’re comprised of neoplastic fibroblastic stroma and normal glands. They’re most frequent in women 20 – 30 years of age. They form firm solitary, mobile, off-whitish well-circumscribed masses. As they are benign they are usually not necessary to remove.
Phyllodes tumour
Phyllodes tumour are similar to fibroadenomas, however their stromal component is more cellular. The name “phyllodes” comes from the Greek word for “leaf-like”, as the stroma often forms leaflike projections. They’re much less common than fibroadenomas. 75% of these are benign, and the remainder are malignant. As they have malignant potential they should be surgically removed.
Intraductal papilloma
Intraductal papilloma is, like the name suggests, a papillary growth that occurs inside dilated ducts. They’re more frequent in premenopausal women. The lesions are small (< 1 cm) and usually solitary. These tumors cause bloody nipple discharge.