Better Me

What Is the Difference Between a Cyst and a Tumor

It’s natural to get some lumps here and there from time to time, such as a pimple or an injury from a bump or fall. Our bodies are wonderfully lumpy and bumpy.

But, when you discover a lump, bump or unusual mass somewhere on your body with no known cause, it can be quite alarming. The first thought for some people is, “Could this be cancer?”

More often than not, that strange bump is generally harmless, like a benign (not cancerous) cyst or tumor.

While you’ll need a health care provider to rule out whether it’s a benign cyst or tumor or something more serious, here are a few things you should know about cysts and tumors.

What is a cyst?

“A cyst is typically a fluid-filled mass or sac-like structure,” said Michael Choti, MD, a surgical oncologist and division chief of surgery at Banner MD Anderson Cancer Center at Banner Gateway Medical Center. “A cyst doesn’t contain solid tissue within it but has its own capsule or wall around it.”

Cysts have a wide range of causes and types. Some are congenital or related to an underlying medical condition such a polycystic ovary syndrome, while other cysts form because of an infection, a clogged duct or damaged hair follicle.

Cysts can range in size and develop anywhere in the body, including the abdomen, brain, joints and on the skin. Some common types of cysts include:

  • Ovarian cyst, an ovarian follicle that doesn’t release its egg may form a cyst on the ovary
  • Breast cyst, a lump that can develop and change in size throughout the menstrual cycle
  • Kidney cyst, a solitary cyst that can be present at birth or develop due to a medical condition, such as polycystic kidney disease
  • Pancreatic cyst, a growth on the pancreas
  • Liver cyst, a fluid-filled sac that forms on the liver
  • Acne cyst, or acne that develops under the skin
  • Epidermoid cyst (also known as a dermoid cyst or dermal/epidermal inclusion cyst), a noncancerous bump found on the face, head, neck, back or genitals
  • Sebaceous cyst, a slow-growing bump under the skin that often appears on the scalp, face, ears, body, back and groin area
  • Ganglion cyst, a bump that forms on or near a joint, often the hand, foot, ankle or knee
  • Baker’s cyst, a lump that forms behind the bend of the knee joint

Can cysts turn into cancer?

Most cysts are benign, but some can also develop into cancer. “Depending on the cyst location and type, some can be precancerous and need to be followed or removed. It can be like a polyp in the colon, each type having varying risk of developing into cancer,” Dr. Choti said.

If you or your health care provider are concerned, the next step typically involves imaging such as an ultrasound, MRI or CT scan. Sometimes a biopsy or sample of fluid (drawn using a needle and syringe) is required. If the cyst doesn’t pose a health threat, you probably won’t need any treatment. “Many cysts don’t cause any symptoms or issues and go away on their own,” Dr. Choti noted. “Other times, your provider may drain or surgically remove the cyst usually with no complications or side effects.”

In rare cases where the cyst is precancerous or next to or inside cancerous tissue, treatment will depend on the type of cancer and whether the cancer has spread.

What are tumors?

Basically, a tumor (also called a neoplasm) is an abnormal growth that develops inside or on the body. Such masses can grow at different rates. They can be benign or malignant (cancerous). Unlike lumps or masses from other causes such as scars, neoplasms often need to be removed because of symptoms and, in some cases, to assure that they are not cancerous.

Are all tumors cancerous?

Like with a cyst, having a tumor doesn’t automatically mean you have cancer. “It can be very concerning for people, and even some physicians, if they notice a mass in a scan,” Dr. Choti said. “But the growth or mass alone won’t always indicate it’s cancerous.”

A tumor can fall into three categories:

  • Cancerous: A malignant tumor can spread into nearby tissues, glands and body parts and be life-threatening. Brain tumors like glioblastoma, pancreatic cancer, squamous cell carcinoma are types of cancerous tumors.
  • Noncancerous: A benign tumor is localized, or restricted to a particular area, and doesn’t typically affect nearby tissues or body parts. These typically don’t require treatment and are rarely life-threatening. Types of noncancerous tumors include brain tumors like meningiomas, benign bone tumors, lymphatic tumors, lipomas and uterine fibroids.
  • Precancerous: This type of tumor can become cancerous if not treated. Colon polyps, breast ductal carcinoma in situ and skin actinic keratoses are types of precancerous tumors. Also, mucinous cysts of the pancreas called IPMN (intraductal papillary mucinous neoplasms) are also considered precancerous.

To determine if your tumor is cancerous, noncancerous or precancerous, your provider will order further testing, which may include a biopsy, bloodwork, and imaging, such as ultrasounds, CT scans, MRI scans and mammogram.

Many noncancerous tumors don’t need treatment, but some benign tumors can continue to grow and may need to be surgically removed. Treatment for cancerous tumors may include surgery, chemotherapy and radiation therapy, immunotherapy and/or targeted therapy.

How can you tell the difference between a cyst and a tumor?

The only way to truly tell the difference between a cyst and a tumor is to have it evaluated by a health care specialist.

See your health care provider right away if your lump or bump:

  • is growing quickly
  • changes color
  • is red or swollen
  • bleeds
  • is painful
  • interferes with your quality of life

Finding a new lump or bump can be unnerving, but don’t let this stop you from getting appropriate care. To find a health care provider near you, visit

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