Patients commonly present to us with an ultrasound showing something they cannot feel. We call these incidental lesions. They may not be felt if they are too small, too deep or if the breast tissue is too dense.
The most common of these are breast cysts. Cysts are also the cause of many breast lumps which you may feel.
The word cyst in medicine refers to a sac filled with fluid. Cysts can be found in many organs such as the liver, kidneys, ovaries and breast. These are usually unrelated so that having cysts in the ovaries does not increase your chance of having breast cysts.
To understand what a breast cyst is, it is useful to understand the structure and function of the glandular part of the breast.
The breast glands are made of lobules and ducts – all of which are lined by secretory cells (ie. Cells that produce fluid).
These secretory cells are always producing fluid and then absorbing it (taking it back up). That’s why we do not see fluid coming out of the nipples all the time.
Cysts arise within the breast lobules where the cells may stop absorbing the fluid back up or there is a blockage which results in the fluid building up inside the lobules producing a cyst.
Cysts are classified based on how they look on ultrasound:
- A simple cyst has fluid only. It can range in size from tiny to very large but usually causes no symptoms. If it is large and painful, it can be drained with a needle under ultrasound guidance. Otherwise, there is no need to do anything else to simple cysts and no need to follow them up with more ultrasound scans.
- A complicated cyst is one where the fluid is thick or the cyst wall itself is thick.
- A complex cyst is one that has solid components inside the cyst wall.
- Complex and complicated cysts may require a biopsy or follow up ultrasound scans.
Surgery is not required for a simple cyst and is rarely required for complicated or complex cysts.