I. Overview and Approach – NUS Pathweb

Let's learn about the histologic components of the breast; its functions, and some important clinical considerations.

1. What is the breast?

Modified skin appendage (sweat gland) -
- Terminal duct lobular unit - small ducts and lobules lined by specialised epithelium, bilayered
  - Myoepithelial - outer, against basement membrane
  - Epithelial - inner - facing lumen - many epithelial proliferations and neoplasms arise from this
- Specialised intralobular stroma
  - Can become neoplastic -> induce proliferation of epithelial cells too -> develop fibroepithelial neoplasms (eg. fibroadenoma, phyllodes tumour)
- These two components are hormonally responsive and may undergo morphologcal changes during various parts of the menstrual cycle, as well as during lactation

Large ducts and lactiferous ducts - larger ducts also lined by bilayered epithelium, the latter open into the nipple. Benign, in-situ and malignant neoplasms can also arise from these (may cause bloody nipple discharge)

2. What are the functions of the breast?

3. Important Clinical Considerations

- As breast cancer is the commonest malignancy in women, one of the key questions when approaching a female patient with a breast complaint is: Is this malignant?

- Even benign lesions (eg. benign epithelial proliferations) may carry an increased risk of malignancy, so these need to be followed-up

- Family history and past history are very important when evaluating a patient for possible breast malignancy

- The triple test - a combination of clinical evaluation (History and physical examination); diagnostic imaging and tissue biopsy, is the mainstay of the diagnostic approach to breast cancer.

In the next section you will learn about some of the main breast diseases, and thereafter the main clinical manifestations of breast disease.

Look at these side by side to work out how individual diseases may be picked up clinically.