Cyst vs. Tumor: What Is the Difference?

Medically Reviewed By Jenneh Rishe, RN
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Cysts and tumors are abnormal growths and have different causes. However, their appearances may be similar. Imaging studies or a biopsy can help determine whether a lump is a cyst or a tumor.  Several conditions cause cysts and tumors. Most cysts and tumors are noncancerous, and many do not require treatment. However, if you notice an unusual growth, seek advice from your medical professional.

This article explores the differences between cysts and tumors. It also discusses diagnosis and when to contact a doctor.

Cyst vs. tumor

Person going through a CT scan
PER Images/Stocksy United

A cyst is a closed, sac-like capsule that may contain fluid, pus, or other material. Cysts can form anywhere on the body and are usually noncancerous. Cysts are typically slow growing and stay localized. They do not spread to surrounding tissue or other parts of the body. 

A tumor is a solid mass of tissue. It occurs when cells grow and divide faster than usual or do not die off when they should. Some tumors are noncancerous, while others can be cancerous. Cancerous tumors are typically fast growing. They can spread to other parts of the body or invade nearby tissues. 

Conditions and types of cysts

There are several conditions that cause cysts and several different types of cysts. Listed below are some common conditions and types.

Breast cysts

Breast cysts are a common diagnosis. They are one of the most common reasons for seeking medical care regarding a breast mass. Breast cysts are part of a condition called fibrotic disease of the breasts.

Irregular breast development causes breast cysts. They are usually fluid sacs that may range in size from small to large. They can also appear as a single cyst or multiple ones.

Some people have no symptoms. Others may experience a palpable lump, pain, or discharge from the nipple. 

Breast cysts usually are noncancerous. Rarely, they may become cancer over time. 

Most breast cysts do not require treatment. Some may disappear after fluid aspiration. Depending on the cyst size and type, the medical professional may suggest follow-up imaging within a certain time frame. 

Epidermoid cysts

Epidermoid cysts, also called sebaceous cysts, are slow-growing keratin-filled capsules in the skin. Keratin is the protein that makes up skin, hair, and nails. These cysts can occur anywhere on the body but usually grow on the face, neck, and trunk. 

Typically, epidermoid cysts are benign, but they do have the potential to become cancerous. 

Treatment usually involves surgical removal of the cyst. If an infection is present, initial treatment may involve draining the cyst and antibiotics

Hepatic cysts

Hepatic cysts are fluid-filled capsules in the liver. A person with a hepatic cyst usually has no symptoms. Doctors may discover the cyst accidentally during imaging studies. 

Typically, hepatic cysts cause no harm. In rare cases, hepatic cysts can cause complications with the biliary tree. These complications include hemorrhage, rupture, or compression. 

Cysts smaller than 4 centimeters (cm) generally do not require treatment. Cysts larger than 4 cm typically require follow-up ultrasounds to monitor growth. Cysts causing symptoms may require surgical removal or aspiration.

Pilar cysts

Pilar cysts, also called trichilemmal cysts, are the most common type of cyst in the skin. However, they typically occur in less than 10% of the population. These slow-growing keratin-filled capsules usually affect the scalp. There is no recorded case of a pilar cyst turning into cancer. 

A more aggressive form of pilar cysts, called proliferating trichilemmal cysts, are rare. These occur in less than 3% of all pilar cysts. Proliferating trichilemmal cysts may cause skin ulcerations and grow aggressively.

Treatment usually consists of surgical removal of the cysts to prevent a recurrence.

Renal cysts

Renal cysts are common findings during imaging studies. Renal cysts occur in about 40% of the population. Most are noncancerous, but some may cause cancer. Cysts growing inside the kidney can cause obstructions. 

Some renal cysts do not require treatment. Depending on the cyst type and location, treatment may involve dialysis and surgical removal of the kidney. 

Ovarian cysts

Ovarian cysts are common fluid-filled sacs on the ovaries. They usually occur or grow during ovulation. Many people have no symptoms. Others, however, may experience bloating, swelling, or abdominal pain. Several types of ovarian cysts exist, most of which are noncancerous. 

Sometimes, ovarian cysts rupture and cause sudden and severe pain. In other cases, they can cause an ovary to twist. This also causes severe pain, along with nausea and vomiting.

Some cysts require surgery when the person is past menopause, or if the cyst does not go away, becomes larger, or looks unusual on an ultrasound. 

Cysts that do not require surgery may require treatment for pain. Hormonal birth control may be helpful for people who have frequent cysts.

Learn more about cysts.

Conditions and types of tumors 

Several conditions cause cancerous and noncancerous tumors to grow. There are also several different types of tumors that can either be cancerous or noncancerous.


Adenomas are noncancerous tumors that grow in gland-like cells of organs, glands, and other structures. Although noncancerous, some adenomas may develop into cancer over time. There are several types of adenomas, including:

Treatment usually involves surgical removal to reduce the risk of possible cancer. 


Fibroids are tumors that develop in muscle tissue, usually in the muscle wall of the uterus. Fibroids are always noncancerous, and many people have no symptoms. People who do have symptoms may experience:

  • heavy menstrual bleeding
  • lower back pain
  • pain during sex
  • reproductive problems
  • full feeling in the pelvic area

People who do not experience symptoms usually do not require treatment. 

People who do have symptoms may require treatment such as:

  • over-the-counter (OTC) pain medications
  • iron supplements for anemia during menstruation
  • low dose birth control 
  • medications to shrink the fibroid
  • surgical removal of the fibroid


Lipomas are common, noncancerous tumors that develop in the fat layer under the skin. They appear as soft lumps, most often on the trunk, arms, or legs. 

Treatment is usually for cosmetic purposes. Weight loss may decrease their size. Liposuction and surgical removal are also treatment options.

Malignant tumors

Malignant tumors are cancerous tumors that can develop anywhere in the body. These tumors contain cells growing out of control. These cells can spread to nearby tissue or to other parts of the body. There are several types of malignant tumors and cancers, including:

  • Sarcomas: This is a cancer of the connective tissues.
  • Carcinomas: This is a cancer of skin or organ tissue.
  • Leukemia: This is a cancer of the blood cells.
  • Lymphoma: This is a cancer of the immune system.
  • Central nervous system cancer: This is a cancer of the brain or spinal cord.

Treatment may include:

Learn more about benign and malignant tumors.

Diagnosing cysts and tumors

Doctors use several methods to determine if a growth is a cyst or a tumor. 

Cysts on the skin do not usually require biopsy or special imaging. Diagnosis typically involves physical examination by a medical professional along with understanding the history of the growth. 

Internal lumps may require other diagnostic tests to determine if they are cysts or tumors. 


A biopsy is removing cells or tissue for examination under a microscope. Several types of biopsies are available, including:

  • Incisional biopsy: This means removing a small tissue sample.
  • Excisional biopsy: This means removing an entire lump or suspicious area.
  • Fine needle or core biopsy: This means removing a sample of tissue or fluid with a needle. 


Diagnostic imaging includes the use of:

  • ultrasound
  • CT scan
  • MRI scan
  • X-ray
  • PET or SPECT scan

Each type of imaging has its strengths and weaknesses. The location of the tumor determines which method of imaging is the most effective. For example, CT scans are great for visualizing bone. An MRI is better for deeper soft tissue or very tiny tumors. 

When to see a doctor

If you see or feel an unusual growth on your body, contact your doctor for an accurate diagnosis. Most tumors and cysts are noncancerous, and many do not require treatment. However, those that are cancerous may grow quickly and require a fast response.

Let your medical professional know immediately if you notice a lump that:

  • changes color
  • grows quickly
  • bleeds or oozes
  • itches
  • ruptures
  • looks red or swollen


Unusual growths on and in the body are common. Cysts and tumors are no exception. Most of the time, these lumps are noncancerous and do not require treatment.

Contact your doctor for an accurate diagnosis of any unusual growth. 

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Medical Reviewer: Jenneh Rishe, RN
Last Review Date: 2022 Sep 21
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