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What’s the difference between a cyst vs. tumor?

Key takeaways:

  • One difference between a cyst vs. tumor is a cyst is a sac-like pocket while a tumor is a mass of abnormal cells.
  • Cysts can be simple (fluid-filled) or complex (containing blood or a solid substance).
  • Simple cysts are common and usually go away on their own. Complex cysts may need treatment.
  • Tumors are a mass of abnormal cells. There are benign tumors and malignant tumors.
  • Sometimes, a cyst may indicate malignancy.
  • An MRI, ultrasound, or CT scan can indicate a need for a follow-up biopsy.

When comparing cysts vs. tumors, they seem to be alike. But they are, in fact, different in crucial ways.

It’s not uncommon to find a lump on your body. When you see your medical practitioner for a brief physical exam, in many cases, they’ll tell you it’s a cyst. Generally, cysts aren’t a cause for concern because any of several conditions causes them.

There are also cases when a lump could constitute a tumor. That doesn’t mean it’s bad news, though. There are benign (non-cancerous) tumors as well as malignant tumors.

What is a cyst?

A simple cyst is a slow-growing, sac-like pocket filled with fluid or a viscous substance.

When you have several cysts (usually on organs) or the cyst is filled with blood or another semi-solid material—usually a thick, cheese-like fluid—it’s called a complex cyst.

Cysts are smooth and tend to grow slowly. Unless they are substantial and pressing on neighboring tissue, cysts aren’t painful.

They can form for several reasons, including infections, chronic inflammation, duct blockages, and inherited diseases.

Simple cysts can go away on their own, but they may come back. If they’re painful or annoying, cysts can be drained or surgically removed.

Where could a cyst appear on my body?

Cysts develop in all kinds of places in and on your body. Most cysts develop on the surface of your body. However, internal cysts can develop on your kidneys, ovaries, breasts, and other organs. Other cysts develop on the bone.

Epidermoid cysts (sometimes called epidermal cysts) are small and form under the skin. The cyst is caused when outer skin cells move deeper into the dermal layer.

A sebaceous cyst forms in your skin’s sebaceous glands, which is a gland in the skin that leads into a hair follicle. When a sebaceous gland becomes blocked, sebum, a cheese-like, thick substance, fills the gland to form the cyst.

Other types of benign skin cysts include cystic acne, a severe form of acne. Cystic acne starts in your skin’s deep layers when bacteria, oils, and skin cells are trapped in your pores.

Can benign cysts form elsewhere in my body?

Cysts can form in your breasts and are mostly benign.

Vaginal and cervical cysts develop because of gland secretion build-up.

Simple cysts on your kidneys are usually fluid-filled pouches that don’t produce symptoms. Family history or a genetic predisposition to develop multiple cysts can result in polycystic kidney disease (PKD). PKD can cause hypertension and lead to renal failure.

Ovarian cysts occur monthly in menstruating women. It’s a normal part of the ovulation cycle. These cysts can also develop after menopause—that said, most of these are benign.

When multiple cysts are present on the ovaries, it’s called polycystic ovary syndrome (PCOS). Most women with PCOS don’t ovulate, as the hormonal imbalance interferes with the growth and release of eggs from the ovaries. That’s why PCOS may be a risk factor for breast cancer and ovarian cancer.

What is a tumor?

A mass of abnormal cells that have grown, mutated, divided, or haven’t died off when they should have is a tumor. Such tumors are said to have solid components.

A benign tumor isn’t cancerous, but a malignant tumor is.

In some cases, benign tumors can cause pain or disfigurement. While a benign tumor may grow, it doesn’t invade neighboring cells or spread (metastasize) to other areas of your body.

A malignant tumor can be invasive, spreading to lymph nodes, organs, or other areas of your body, such as your spine or brain.

What are benign tumors?

cyst vs tumor: Father and son smiling at each other while outdoors

Some people may have benign tumors for their whole lives. For example, moles are benign tumors that won’t always require treatment.

Other types of benign tumors include:

  • Adenomas, which appear on gastrointestinal tract surfaces. A colon polyp is an example of this.
  • Fibromas, or connective tissue tumors in any organ. They’re named for the organ—for example, plantar fibromas are in the arch of the foot.
  • Leiomyomas, which are gynecological tumors. Hormones fuel their growth. Uterine fibroids (fibromas) are an example of this kind of tumor.
  • Desmoid tumors, a non-cancerous growth. They don’t metastasize, but they may move into nearby tissue and organs.
  • Hemangiomas, which are made up of a collection of blood vessel cells. They can appear in your skin or internal organs. They have a birthmark-like appearance and frequently disappear without treatment.
  • Lipomas, a slow-growing fatty tumor often found between your skin and the underlying muscle layer.

When do you need to further investigate a cyst vs. tumor?

A malignant tumor appears suddenly and tends to be painless and hard. You might be able to feel such a tumor in your breast or testicles or on your neck, arms, or legs.

A mass larger than 1 inch or 2 centimeters that grows steadily over time is cause for concern. You should seek medical advice from your healthcare provider.

How do medical providers decide if my cyst or tumor is malignant (cancerous)?

According to the Mayo Clinic, cysts that look uniform on an MRI, CT scan, or ultrasound are nearly always benign.

It’s also worth noting that potentially malignant cysts secrete mucus. So, mucus secretion could be another way to identify cancerous cysts.

Cysts that have solid components can be either malignant or benign. These cysts will require follow-ups, such as repeat imaging and examination. Your doctor will want to see if it grows over time.

A biopsy remains the only conclusive way to tell if your cyst or tumor is benign. Your clinician takes tissue samples from the growth and sends them to the pathology lab for microscopic evaluation.

Can a CT scan show the difference between a cyst and a tumor?

A computed tomography (CT) scan uses multiple low-dose X-rays to show cross-sectional slices of your cyst or tumor. Think of that slice as similar to an onion slice—the technician can see inside your lump, which helps them determine if a biopsy is necessary.

CT scans show the location, size, and shape of the tumor or cyst. Because CT scans provide clear and accurate information, your medical practitioner may use a scan to guide a needle biopsy.

How do I get a CT scan or ultrasound?

If your lump is very small and not causing problems, your medical provider may suggest just monitoring it during physical exams.

However, you may feel more reassured if you take a look inside your body. You can easily arrange for a full-body MRI, a mammogram, or a low-dose CT scan without a medical order.

If a lump or growth appears on your body, it’s normal to feel concerned. Take control of your health by scheduling a regular, annual full-body MRI screening with Ezra.