Is That Lump a Cyst? Why Your Body Forms Them & Medical Next Steps

Finding a lump under your skin can be unsettling. One common cause is a cyst. In many cases, a cyst is harmless. But sometimes it needs medical attention. Understanding what a cyst is, why it forms, and when to see a doctor can help you respond calmly and wisely.

What Is a Cyst?

A cyst is a closed sac-like pocket of tissue that can form anywhere in the body. It usually contains fluid, pus, air, or semi-solid material. Cysts can develop in the skin, under the skin, or even inside organs.

Most cysts grow slowly and are noncancerous (benign). However, not every lump is a cyst, and not every cyst is harmless. That's why proper evaluation matters.

Common Types of Cysts

There are many types of cysts, but some are more common than others:

1. Epidermoid Cyst (Often Called a "Sebaceous Cyst")

• Forms under the skin
• Usually feels like a small, round bump
• May have a visible central pore
• Often found on the face, neck, or trunk
• Can become inflamed or infected

2. Pilar Cyst

• Typically found on the scalp
• Often runs in families
• Firm and smooth to the touch

3. Ganglion Cyst

• Usually appears near joints (like the wrist)
• Filled with thick, jelly-like fluid
• May change size over time

4. Ovarian Cyst

• Develops on or inside the ovaries
• Often related to the menstrual cycle
• Many cause no symptoms

5. Breast Cyst

• Fluid-filled sac in breast tissue
• Common in women ages 35–50
• May feel tender before a period

Why Does the Body Form a Cyst?

A cyst forms when normal processes in the body become blocked or disrupted.

Here are common reasons:

• Blocked ducts or glands – For example, blocked oil glands can lead to an epidermoid cyst.
• Infection – Certain infections can trigger cyst formation.
• Chronic inflammation – Ongoing irritation may lead to tissue changes.
• Injury or trauma – Damage to skin or tissue can trap cells beneath the surface.
• Genetic conditions – Some inherited disorders increase the likelihood of cyst formation.
• Hormonal changes – Particularly with ovarian cysts.

In the case of an epidermoid cyst, skin cells that should shed normally instead move deeper into the skin and multiply. These trapped cells form the cyst wall and produce keratin, a soft, cheese-like material that fills the sac.

If you've noticed a small, round bump under your skin and want to quickly assess whether it might be an Epidermoid Cyst, a free AI-powered symptom checker can help you understand your symptoms and determine your next steps.

What Does a Cyst Feel Like?

A typical cyst may:

• Feel smooth and round
• Move slightly under the skin
• Grow slowly over time
• Be painless (unless infected)
• Become red or tender if inflamed

However, not all lumps are cysts. A lump that is very hard, fixed in place, rapidly growing, or associated with other symptoms deserves prompt medical attention.

When Is a Cyst a Problem?

Most cysts are harmless and do not require treatment. But some situations call for medical evaluation:

• Rapid growth
• Persistent pain
• Redness, warmth, or swelling
• Drainage of pus or foul-smelling material
• Fever
• Interference with movement or daily activities
• Changes in breast lumps
• Severe abdominal or pelvic pain (possible ovarian cyst complications)

Rarely, what appears to be a cyst may actually be a tumor, including cancer. This is uncommon, but it is why proper assessment matters.

How Are Cysts Diagnosed?

Doctors diagnose a cyst based on:

• Physical examination
• Medical history
• Imaging tests, such as:
  • Ultrasound
  • MRI
  • CT scan
• Biopsy, if needed

For skin cysts, a physical exam is often enough. For deeper cysts (like ovarian cysts), imaging is typically required.

If there is any uncertainty about whether a lump is a cyst or something more serious, your doctor may recommend further testing.

Should You Try to Pop a Cyst?

No. Trying to squeeze or pop a cyst at home can:

• Cause infection
• Increase inflammation
• Lead to scarring
• Push contents deeper into the skin
• Delay proper diagnosis

Even if a cyst drains on its own, it can refill because the cyst wall remains intact. Complete removal often requires a minor medical procedure.

Treatment Options for a Cyst

Treatment depends on the type, size, location, and symptoms.

Watchful Waiting

If the cyst is:

• Small
• Painless
• Not infected
• Not interfering with function

Your doctor may recommend simply monitoring it.

Medications

• Antibiotics for infected cysts
• Steroid injections to reduce inflammation

Drainage

A doctor may:

• Make a small incision
• Drain the fluid or pus

This relieves discomfort but does not always prevent recurrence.

Surgical Removal

For cysts that:

• Recur frequently
• Cause discomfort
• Are cosmetically concerning
• Show suspicious features

Complete surgical removal may be recommended. This is typically a simple outpatient procedure.

Can a Cyst Turn Into Cancer?

Most cysts do not become cancerous.

However:

• Some ovarian cysts require close monitoring.
• Complex cysts seen on imaging may need further testing.
• Any unusual changes in a cyst should be evaluated.

If a lump is new, changing, or accompanied by systemic symptoms (like unexplained weight loss or persistent fatigue), speak to a doctor promptly.

How to Monitor a Cyst at Home

If your doctor recommends observation, you can:

• Measure the size occasionally
• Take note of pain or tenderness
• Watch for redness or drainage
• Track any changes over time

Keep a simple record so you can report accurate information at follow-up visits.

When to Seek Urgent Care

Get immediate medical attention if you experience:

• Severe abdominal or pelvic pain
• Sudden swelling and intense pain
• High fever with a painful lump
• Signs of spreading infection (red streaks, worsening redness)
• A breast lump that changes quickly
• A hard, fixed mass that does not move

While many cysts are benign, serious symptoms should never be ignored.

The Bottom Line: Is That Lump a Cyst?

It might be. Cysts are common, especially under the skin. They often form because of blocked glands, trapped skin cells, or natural hormonal changes.

Most cysts:

• Are noncancerous
• Grow slowly
• Cause minimal symptoms
• Can be safely monitored or easily treated

However, not every lump is a cyst. Proper evaluation helps rule out more serious conditions and gives peace of mind.

If you notice a new lump, changes in an existing one, or symptoms that concern you, speak to a doctor. Only a healthcare professional can provide a clear diagnosis and guide appropriate treatment. If there is any possibility that the lump could be life-threatening or serious, do not delay seeking medical care.

Early evaluation does not mean something is wrong. It simply means you are taking your health seriously — which is always the right next step.