Fibrocystic change (FCC) is a general term used to describe a group of non-cancerous changes that often develop together in the breast. It is a common finding seen in up to 60% of reproductive-aged women. FCC is believed to develop in response to stimulation from hormones such as estrogen and progesterone.
Adult breast tissue is made up of small structures called glands which are organized into groups called lobules. Under certain conditions, these glands can produce milk, which is transported to the nipple by a series of small channels called ducts.
The inside of both glands and ducts is lined by specialized cells called epithelial cells which form a barrier called the epithelium. The tissue surrounding glands and ducts is called stroma and contains long, thin cells called fibroblasts.
In normal, healthy breast tissue, the ducts and glands are lined by a single layer of epithelial cells. Pathologists describe these cells as cuboidal because each cell is as tall as it is wide (like a square).
The diagnosis of fibrocystic change (FCC) can be made after a small sample of tissue is removed from the breast in a procedure called a core needle biopsy. The biopsy may be performed after densities or calcifications were seen on mammography. FCC can also be seen in tissue removed to diagnose or treat cancer or other non-cancerous condition in the same breast.
Normal glands in the breast are small, round structures that often look empty when examined under the microscope. A cyst is an enlarged, fluid-filled gland. These cysts can be single or numerous and may be varied in size.
When groups of cysts or single cysts become large enough, they can be felt when the breast is examined. Over time, some of the calcium in the fluid is left in the tissue where it creates calcifications. These large cysts and calcifications can be seen as abnormalities on ultrasound or mammography.
If a cyst breaks, the fluid inside will spill into the surrounding stroma. This can cause inflammation and the creation of new stromal fibroblasts. Over time this reaction can create a scar that pathologists describe as fibrosis.
Metaplasia is a word that pathologists use to describe a change from the normal cell type to another cell type. It is a non-cancerous type of change. In apocrine metaplasia, the epithelial cells lining the breast ducts change from columnar cells to apocrine cells. Apocrine cells are easy to see under the microscope because they are larger than normal cells and the body of the cell (the cytoplasm) is bright pink.
Adenosis means an increased number of glands in the breast. It is also a non-cancerous change. The new glands may be larger than the normal glands and some may contain fluid. Adenosis is often seen together with columnar cell change and columnar cell hyperplasia.
Fibrocystic changes are not associated with an increased risk of developing breast cancer.