What’s the Difference Between a Tumor and a Cyst?

If you’ve ever developed a hard lump or soft bump on any part of your body, you’ve probably felt worried. Any new growth on your body that shouldn’t be there can be concerning.

You may be curious about what caused the bump, lump, or soft spot to form. You may worry that it’s cancer. And you may wonder if you need treatment.

These lumps and bumps may be tumors or cysts. If symptoms have you wondering — is it a cyst or a tumor? — here’s what you need to know.

What’s the Difference Between a Tumor and a Cyst?

Your body is a complex and highly organized system. It’s always changing as cells mature and die. When old or damaged cells die, new cells form to replace them.

Cells communicate with each other to keep this system in balance. Your genes tell cells to divide and form new cells during a process called mitosis. Individual cells copy their contents and then split to form two new cells that are the same.

Sometimes, things go wrong during this process. Cells may divide and grow too quickly, or cells may not die as they should. This causes clumps of cells called tumors to form.

Cysts are not the same as tumors. Cysts happen when fluid, cells, or air collect and become trapped inside your body.

A cyst may grow bigger, but it doesn’t spread. It may or may not cause symptoms.

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What Is a Tumor?

Many people think of cancer when they hear the word tumor. But having a tumor doesn’t always mean you have cancer. Some tumors are benign, meaning no cancer cells are present.

When tumors include cancer cells, the tumors are malignant. Malignant tumors can grow into nearby areas or spread cancer cells to other parts of your body. When this happens, you have metastatic cancer.

Tumors can form in different types of tissue. Benign tumor types include:

  • Adenomas: Tumors that begin in the flat cells of tissues that cover organs and glands.
  • Lipomas: Fatty tumors that form in soft tissue.
  • Fibroids: Tumors that form in smooth muscle tissue.
  • Hemangiomas: Tumors that form when blood vessels build up in the skin or an organ.

Benign tumors don’t spread. But all tumor types can become large and cause symptoms. They may press on nearby nerves or interfere with body functions.

Depending on where they’re located, tumors may cause:

  • Swelling or pain.
  • Headaches or changes in how you think.
  • Changes to your vision or hearing.
  • Changes in bowel movements, such as constipation or diarrhea.
  • Coughing or trouble breathing.

What Is a Cyst?

Think of a cyst as a little pouch that forms somewhere in your body. Cells and tissue create this pouch. It may fill with air, fluid, or pus.

You can get a cyst anywhere. But cysts often form in:

  • Skin
  • Ovaries
  • Breasts
  • Kidneys

Depending on the cyst’s location, you may notice a bump or swelling. You may have pain, redness, or tenderness in the area. Sometimes, a cyst causes no symptoms at all, but is visible when you have imaging tests for some other reason.

Your doctor will ask if you’re experiencing pain. If you can see the cyst, they’ll ask:

  • When you saw it for the first time.
  • If the cyst has gotten bigger since you first saw it.

How Doctors Determine If It’s a Cyst or a Tumor

Your doctor will ask about any symptoms you have. They do a physical examination. They ask about your medical history and whether others in your family have had cancer or tumors.

Doctors can sometimes diagnose cysts just by looking at them. But they may need more information. Your doctor may recommend tests such as:

Imaging tests

Imaging tests help doctors visualize parts of your body. You may have a:

  • Computed tomography (CT) scan: A special type of X-ray that takes pictures from many different directions. Together, these different images create a 3-D image.
  • Magnetic resonance imaging (MRI): A test that uses strong magnets and radio waves to create images. These pictures help your doctor see changes to your body’s tissue.
  • Positron emission tomography (PET) scan: Doctors inject a dye into your vein. They take images to see how your cells absorb the dye. This test helps doctors find cancer cells.
  • Ultrasound: Doctors move a hand-held device (transducer) over your skin. The transducer sends sound waves to a computer, which creates images on a monitor.


Biopsy is a test that tells doctors more about the cells inside a cyst or tumor. Doctors use a needle or make a small incision to remove a small sample of tissue or fluid from the area. Specialists examine the sample under a microscope to see if it contains cancer cells.

Laboratory tests

Doctors take a sample of your blood. They look for proteins and other substances (biomarkers) that may indicate cancer. They may also check your kidney and liver function.

Do I Need Treatment for a Cyst or Tumor?

Benign tumors and cysts don’t always need treatment. Some resolve on their own. Your doctor may treat you if the growth:

  • Contains cancer cells or is a precancerous growth (cells that could become cancer).
  • Causes pain or discomfort.
  • Interferes with your activities or body functions.

How doctors treat cysts

When a cyst is large or causes discomfort, your doctor may:

  • Drain it by inserting a needle into the cyst to draw out fluid or tissue.
  • Perform surgery to remove the cyst.

How doctors treat tumors

When tumors are benign, doctors may observe them over time to see if they change in size (known as watchful waiting). If the tumor is large or causing symptoms, doctors may perform surgery to remove it.

Malignant tumors usually require more aggressive treatment. If a tumor is cancerous, doctors may remove it with surgery. Or they may treat you with other cancer treatments, such as:

You may also have these treatments before or after surgery. Doctors may also freeze some malignant tumors (cryotherapy) or treat them with light (photodynamic therapy).

Talk to Your Doctor

It’s important to talk to your doctor when you notice any new growth or lump. An exam and testing can help determine if it’s a cyst or a tumor. Treatment, if needed, can help relieve symptoms and protect your health.

MedlinePlus, Cyst, https://medlineplus.gov/ency/article/003240.htm

MedlinePlus, Tumor, https://medlineplus.gov/ency/article/001310.htm

MedlinePlus, How Do Cells Divide?, https://medlineplus.gov/genetics/understanding/howgeneswork/cellsdivide/

Harvard Health Publishing, Harvard Medical School, Cysts (Overview), https://www.health.harvard.edu/a_to_z/cysts-overview-a-to-z

UPMC.com, Ultrasound at UPMC Imaging Services, https://www.upmc.com/services/imaging/services/ultrasound

NHS, Skin Cyst, https://www.nhs.uk/conditions/skin-cyst/

National Cancer Institute, What Is Cancer?, https://www.cancer.gov/about-cancer/understanding/what-is-cancer

National Cancer Institute, How Cancer Is Diagnosed, https://www.cancer.gov/about-cancer/diagnosis-staging/diagnosis

American Cancer Society, Signs and Symptoms of Cancer, https://www.cancer.org/treatment/understanding-your-diagnosis/signs-and-symptoms-of-cancer.html

National Cancer Institute, Adenoma, https://www.cancer.gov/publications/dictionaries/cancer-terms/def/adenoma

National Cancer Institute, Fibroid, https://www.cancer.gov/publications/dictionaries/cancer-terms/def/fibroid

OrthoInfo, Lipoma, https://orthoinfo.aaos.org/en/diseases--conditions/lipoma

MedlinePlus, Cancer Treatments, https://medlineplus.gov/ency/patientinstructions/000901.htm

About UPMC Hillman Cancer Center

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