Cysts

Overview

A cyst is an abnormal growth shaped like a sac, pouch or capsule. It can be filled with air, fluid, pus or tissue, and it can form almost anywhere in the body. Cysts are different from tumors, and they are almost always benign (not cancer).

What Causes a Cyst

A cyst forms when something in the body gets blocked, such as a duct that carries or drains fluid. An infection or another problem in the duct or the tissue nearby can cause the blockage. Air, fluid, blood or pus then builds up, and a sac forms around it. The sac and what is inside it make up the cyst.

Common Types

• Cysts under the skin, such as ganglion, sebaceous, pilonidal and dermoid cysts
• Fibrous and simple breast cysts
• Follicular and dermoid ovarian cysts, and polycystic ovaries
• Simple kidney (renal) cysts, and polycystic kidney disease

Symptoms

Cysts come in many sizes and shapes. Some can be felt with the hand; others are deep in the body and show up only on x-rays or other imaging tests. A cyst you can feel is often soft if it holds air or fluid, and firmer if it is filled with tissue.

Is a Cyst Cancer?

Almost never. Cysts contain some cells, but usually not the abnormal cells that make up a cancerous tumor. Some cysts, though, contain cells with abnormal changes, and these can possibly turn into cancer.

Cyst or Tumor?

• Most cysts are benign; tumors can be benign or malignant.
• A cyst is a sac filled with air, fluid, pus or tissue; a tumor is made of abnormal cells.
• A cyst forms because of a blockage or an infection; a tumor forms when something goes wrong in the cell cycle and abnormal cells grow into a lump.

Does a Cyst Need to Be Removed?

Some cysts are removed because of their size, their place or other concerns; others can be left alone. A cyst that holds fluid or pus may go away after it is drained, but it can fill up again, or a new cyst can form in the same place. Have a doctor check any cyst that changes size or shape or causes symptoms.

Questions to Ask Your Doctor

• How sure are you that this is a cyst and not a tumor, and do I need an imaging test to be certain?
• What do you think caused this cyst to form?
• Do the cells in this cyst show any abnormal changes?
• Should this cyst be drained or removed, or can we leave it alone?
• What changes in size, shape or symptoms should make me come back?

Source: https://www.cancer.org/cancer/understanding-cancer/what-is-cancer/cysts.html