August 24, 2023
August 24, 2023

Cyst vs. Tumor: What’s the Difference? What You Need to Know

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Cyst vs. Tumor: What’s the Difference? What You Need to Know

You’ll often hear the terms “lesion,” “cyst,” and “tumor” used interchangeably, yet they carry distinct meanings in medical context. Each represents a different type of tissue abnormality.

“Lesion” is the umbrella term given to any abnormal area of tissue. Lesions can occur in any tissue or organ in your body and take various forms, including that of a cyst or tumor. They may be benign (noncancerous) or malignant (cancerous), and their appearance, size, color, and texture can vary widely. Like cysts and tumors, lesions can be caused by a range of factors, including infections, autoimmune diseases, chronic conditions, and cancer.

Here, we’ll delve into the similarities and differences between a cyst vs. tumor. We’ll go into some detail about where you might find tumors and cysts, discuss different types, and cover what testing is needed to diagnose them. We’ll also answer some of the most frequently asked questions about cysts vs. tumors.

Cyst vs. Tumor: What’s the Difference?

A cyst is generally a slow-growing, sac-like pocket of tissue that may contain pus, fluid, air, or other substances. Cysts are usually uniform, smooth, and painless until they become significantly larger. They can form due to infections, chronic inflammation, blockages, or inherited diseases.

There are two types of tumors also called neoplasms: Cancerous ones (malignant) and non-cancerous ones (benign). 

A benign tumor grows slowly and is generally harmless — unless it becomes large enough to compress blood vessels, nerves, or other structures, which may cause pain or interfere with functioning. A benign tumor will not spread to other areas.

A malignant (cancerous) tumor grows faster and features rough edges and irregular boundaries. Cancerous tumors can spread to nearby tissues or other parts of the body through the lymph system. 

Some benign tumors can turn into cancer later on — for example, this can be the case with colon polyps and skin moles. Your healthcare provider should routinely check your benign lesions for changes or growth.

What Are the Most Common Types of Cysts?

Cyst vs tumor: Doctor examining a patient's neck area

Numerous types of cysts can develop in various parts of the body, each with its own characteristics. Here are some of the most common ones.

Sebaceous cysts: These cysts form in the sebaceous glands that produce the oily substance (sebum) that coats the skin and hair. They’re usually caused by blocked glands or hair follicles.

Epidermoid cysts: Also known as epidermal cysts, they develop in the top layer of the skin (epidermis) and are filled with keratin, a protein that's found in skin, hair, and nails.

Pilar cysts: These cysts, filled with keratin, form around hair follicles and are most commonly found on the scalp.

Ovarian cysts: These cysts develop in or on the ovaries. They're most often caused by the normal function of the menstrual cycle but can sometimes be a sign of a hormonal imbalance or another condition. When multiple cysts are present on the ovaries, it’s called polycystic ovary syndrome (PCOS). Most women with PCOS don’t experience ovulation, as the hormonal imbalance interferes with the growth and release of eggs from the ovaries. PCOS may be a risk factor for breast cancer and ovarian cancer.

Baker's cysts: Also known as popliteal cysts, these fluid-filled cysts form behind the knee, often due to arthritis or a knee injury.

Breast cysts: These are fluid-filled sacs that develop in the breasts and are more common in premenopausal women. Large cysts and clusters of small cysts can usually be seen on a mammogram.

Kidney cysts: These cysts form on the kidneys and are usually harmless. However, some may be associated with polycystic kidney disease or other serious conditions.

Ganglion cysts: These are noncancerous lumps filled with a jelly-like fluid that most commonly develop along the tendons or joints of the wrists or hands.

Chalazions: These cysts form on the eyelids due to blocked oil glands and may resemble a stye.

Dermoid cysts: These cysts may contain skin, hair, and other tissues and are usually present at birth.

Liver cysts: These usually appear alone, though they sometimes occur in groups. The cause of liver cysts is usually unknown, and they may be present from birth.

While many cysts are benign and may not require treatment, they can sometimes cause discomfort or other complications. That’s why it's important to consult with a health care provider if you have concerns about a cyst.

How Common Are Benign Tumors?

As previously discussed, benign tumors may become cancerous in the future. However, some people have benign tumors that remain unchanged their entire lives. Here’s a closer look at some common types of benign tumors.

Fibromas: Connective tissue tumors that can occur in any organ, they’re named for the organ they’re present in—for example, plantar fibromas are in the arch of the foot.

Leiomyomas: Another word for these is fibroids. These are benign tumors that arise from the smooth muscle layer (myometrium) of the uterus. They can vary greatly in size from small, barely detectable nodules to large masses that can distort and enlarge the uterus. A woman can have more than one leiomyoma at a time.

Desmoid tumors: A noncancerous growth, these don’t metastasize, but they may move into nearby tissue and organs.

Lipomas: This is a slow-growing fatty tumor often found between your skin and the underlying connective tissue.

Do Cancer Lumps Feel the Same as Cysts? Do They Hurt When You Press Them? 

Distinguishing between a benign cyst or a cancerous tumor isn’t always straightforward. The following are general characteristics of each type of lesion.


  • Usually round, smooth, and movable
  • May be filled with fluid or other material
  • Most often painless, but they can sometimes be tender

Cancerous lumps or tumors

  • Are often hard, irregular, and fixed in place (do not move when you touch them)
  • May be painful or painless
  • Tend to grow quickly
  • May change in shape, color, or appearance over time

As you see, there’s a lot of overlap between the two. If you have a suspicious lump, seek the advice of your health care provider, especially if it’s larger than 1 inch (or 2 centimeters) with consistent growth.

Can a Medical Provider Distinguish Between Cysts, Tumors, and Cancerous Lesions?

Cyst vs tumor: Doctor reassuring patient during an exam

You may wonder if a medical provider can distinguish between cyst vs. tumor vs. cancerous lesion. The following methods will help your health care provider understand the nature of the lesion and decide on the best treatment course.

Physical examination

Often, the initial step in the evaluation process involves a physical examination. Although this alone cannot definitively diagnose cancer, it can provide valuable insight. For instance, malignant tumors often manifest as painless, hard masses that may appear suddenly. 

Imaging tests

Imaging studies help tell the difference between a cyst vs. tumor; they may also help differentiate between benign and suspicious abnormalities. Advanced imaging technologies such as magnetic resonance imaging (MRI), computed tomography (CT scan), or ultrasound are commonly used to assess the nature of the growth. Typically, cysts that appear uniform in these scans are mostly benign. On the other hand, if the cyst or tumor shows solid components or irregular features, it may warrant a more detailed investigation, as it could be either benign or cancerous (malignant). 

Follow-up examinations and repeat imaging

For cysts or tumors exhibiting atypical characteristics, regular follow-up examinations and repeat imaging might be recommended. This surveillance helps to observe any growth over time, which could suggest malignancy.


The gold standard method to confirm the nature of a cyst or tumor is a biopsy. In this procedure, a sample of tissue from the abnormal growth is obtained and sent for microscopic examination in a pathology lab. This analysis can accurately determine whether the growth is benign or malignant, providing vital information for appropriate treatment planning.

Can a Cyst Turn Into a Tumor?

Cysts and tumors are distinct entities, and a cyst does not typically "turn into" a tumor. However, there are rare exceptions. According to Stanford Medicine, a cyst may develop or contain malignant cancer cells either in its lining or in the fluid contained within.

For instance, intraductal papillary mucinous neoplasms (IPMNs) and mucinous cystic neoplasms (MCNs) that grow in the pancreas are considered “precancerous cysts.” Patients with known IPMNs should be vigilant, as it is difficult to predict which cysts will develop or harbor cancer cells.

MCNs which usually occur in the tail and body of the pancreas are another type of precancerous cysts. These are more common in women than men, and larger cystic lesions with compartmented linings are more likely to harbor cancerous cells.

Research published in “Gland Surgery” indicates that diagnostic imaging studies like MRI scans l) have drastically improved the early diagnosis of cancer. It’s important to have yearly scans for the best chance to spot cancer earlier when it is smaller and easlier to treat. 

Get to Know Your Risk Factors and Take Control of Your Health

Distinguishing between a cyst vs. tumor can be challenging, given the complex nature of these lesions and their diverse presentations. Moreover, the potential of a cyst to contain malignant cells, although a rare occurrence, necessitates a comprehensive understanding and appropriate management.

Awareness, early detection, and proactive measures remain key in managing potential risks and maintaining optimal health. In this light, knowing your risk factors can be a game-changer. 

To gain critical insight into your personal health, take Ezra Scan’s 5-minute risk assessment. Simply provide information about your medical history, family health background, and lifestyle habits. An advanced algorithm will calculate your risk scores, helping you understand and navigate your health landscape better. 

Book your Ezra Full Body MRI and begin your journey toward better health awareness and management.