How to tell if something is a cyst or not: The Ultimate Guide

September 24, 2025 •

4 min read

Over 20% of adults may experience a common type of benign skin cyst at some point, yet many wonder about its nature. A primary distinction of a cyst is that it's a closed sac-like growth with a distinct membrane, filled with various substances. This guide will help you understand how to tell if something is a cyst or not by examining its physical traits and comparing it to other common skin conditions.

Quick Summary

Assessing a lump's texture, mobility, and growth rate provides initial clues to its identity. Cysts are often firm, movable sacs that grow slowly, unlike abscesses, which are tender, pus-filled infections, or lipomas, which are soft, fatty tumors. For an accurate diagnosis and treatment plan, professional medical advice is essential.

Key Points

Check its mobility: Cysts can often be moved slightly under the skin, while other growths might feel more fixed in place.
Assess the texture: A cyst can feel firm or pliable depending on its contents, distinguishing it from a soft, doughy lipoma or a tender, warm abscess.
Look for a punctum: Epidermoid cysts frequently have a small, dark pore or plug at the center of the bump.
Track its growth rate: Cysts typically grow slowly over time, whereas an abscess can swell rapidly due to infection.
Monitor for pain: Most cysts are painless unless infected, while an abscess is usually painful and a lipoma is almost never painful.
Consult a professional for a definitive answer: Because different lumps can have similar appearances, a medical evaluation is the only way to get an accurate diagnosis.

What is a cyst?

Before you can know how to tell if something is a cyst or not, it's crucial to understand what a cyst actually is. A cyst is a sac-like pocket of membranous tissue that contains fluid, pus, air, or other material. Unlike a tumor, it is almost always benign and is typically a result of a blocked duct or gland. The lining, or capsule, is what distinguishes a true cyst from other lumps. They can develop just under the skin or much deeper inside the body, and their size can vary from microscopic to several inches across.

Physical characteristics to examine

When you discover an unexplained lump, performing a simple self-examination of its appearance and feel can offer valuable insight. Remember that this is not a substitute for a professional diagnosis.

Appearance: A skin cyst often presents as a round, dome-shaped bump that may be skin-colored, yellowish, or tan. Some cysts, particularly epidermoid cysts, may have a small, dark opening in the center, known as a punctum. If infected, it can become red and swollen.
Texture: The texture of a cyst depends on its contents. If filled with fluid or pus, it may feel soft or pliable to the touch. If it contains tissue, it may feel more firm and solid. A key differentiator is that it will feel encapsulated, not just a random collection of tissue.
Mobility: Many superficial cysts can be moved around slightly under the skin when you apply gentle pressure, unlike some other growths that feel firmly rooted in place.
Growth Rate: Cysts typically grow slowly over time. If a lump appears and grows very rapidly, it might indicate an infection or a different type of mass.

Cyst vs. other common bumps

Distinguishing a cyst from other common growths, such as a lipoma or an abscess, is a critical step in a preliminary assessment. The following comparison table highlights the major differences.


Feature	Cyst	Abscess	Lipoma
Origin	Blocked gland or duct leads to a membranous sac with fluid or keratin	Bacterial or fungal infection creating a pocket of pus	Accumulation of fatty tissue between skin and muscle
Texture	Firm, but can be pliable and encapsulated; may feel like a contained sac	Soft, warm, tender, and swollen due to infection and inflammation	Soft, doughy, and movable or “squishy” under the skin
Pain	Usually painless unless it becomes inflamed, infected, or ruptured	Typically painful and tender due to inflammation and pressure	Usually painless, unless it presses against a nerve
Growth	Slow, gradual growth	Can develop and grow rapidly, often with intense inflammation	Very slow growth over a long period
Contagious?	No	Yes, the pus is contagious and can spread infection	No

When to seek a professional diagnosis

While a self-assessment can offer an initial idea, only a medical professional can provide a definitive diagnosis. It is always wise to consult a doctor for any new or changing lump, especially if you experience any of the following warning signs:

Rapid Growth: A lump that increases in size quickly.
Painful or Infected: A lump that becomes red, warm, tender, or shows signs of drainage.
Hard and Immovable: A lump that is very hard and doesn't move easily beneath the skin could be a concern.
Irregular Borders: A lump with an irregular, non-symmetrical outline.
Concerning Location: A lump found in the breast, testicles, or that is accompanied by other symptoms like fever or weight loss.
After Removal: A lump that grows back after being treated or removed.

The diagnosis process

A doctor will typically begin with a physical examination to assess the lump's size, texture, and mobility. Based on their findings, they may recommend further evaluation.

Diagnostic Imaging: Imaging tests like an ultrasound can determine if the lump is solid or fluid-filled. More advanced scans like a CT or MRI may be used for deeper masses.
Biopsy: For a definitive diagnosis, a doctor may perform a biopsy, which involves removing a small tissue sample for lab analysis. This is the only way to confirm if a lump is cancerous.
Fine-Needle Aspiration: If the lump is fluid-filled, a needle may be used to draw out a sample of the fluid for analysis.

Types of cysts by location

Cysts can occur almost anywhere on the body, with their location often providing clues to their type:

Epidermoid Cysts: The most common type, occurring just under the skin on the face, neck, and trunk.
Pilar Cysts: Form in hair follicles, most commonly on the scalp.
Ganglion Cysts: Develop on joints or tendons, especially the wrists and hands.
Baker's Cysts: Fluid-filled sacs that form behind the knee.
Ovarian Cysts: Common in menstruating individuals, forming on or inside the ovaries.

Preventing cysts

While many cysts are not preventable, some steps can help reduce the likelihood of developing certain types:

Maintain Good Hygiene: Proper hygiene can help prevent some types of skin infections that can lead to abscesses or infected cysts.
Moisturize: Keeping skin healthy and supple can help prevent some blockages. Use non-comedogenic facial products to avoid clogging pores, which can lead to cystic acne.
Avoid Popping: Never try to pop or squeeze a cyst at home. This can cause the infection to spread, lead to further inflammation, or damage the skin, causing scarring.

Conclusion: Your health is worth the peace of mind

Understanding how to tell if something is a cyst or not based on its physical characteristics is a useful first step, but it is not a diagnosis. The potential differences between a harmless cyst and a more serious condition, like a tumor or an infection, highlight the importance of professional medical advice. Always consult a healthcare provider for any new or unusual lumps. For more information on identifying skin growths and when to seek help, consider resources from reputable health institutions like the American Cancer Society, which can provide additional context and guidance regarding skin and other conditions. Seeking professional evaluation ensures proper diagnosis and treatment, giving you peace of mind and protecting your health.

Frequently Asked Questions

No, you cannot definitively tell if a lump is a cyst just by looking. While visual clues like a central dark spot or being dome-shaped can be suggestive, a professional medical evaluation is the only way to get a conclusive diagnosis, especially to rule out more serious conditions.

The main difference lies in their contents and feel. A cyst is a sac containing various substances and can feel firm. A lipoma is a benign tumor made of fatty tissue and typically feels soft, doughy, and moves easily under the skin.

An infected cyst often becomes red, swollen, warm to the touch, and tender or painful. You might also notice pus or other discharge from it, which distinguishes it from an uninfected cyst.

You should never try to pop or squeeze a cyst. Doing so can push bacteria deeper into the skin, spread infection, and increase the risk of scarring. In many cases, if the cyst wall is not fully removed, it will simply grow back.

Some cysts, particularly smaller ones, may resolve on their own, but many persist indefinitely. For some types, like ovarian or ganglion cysts, they may fluctuate in size or disappear and reappear. If a cyst is causing issues or persists, medical intervention may be necessary.

See a doctor if a lump grows rapidly, is hard and immovable, is painful, shows signs of infection (redness, pus), or appears in a sensitive area like the breast or testicles. Any unexplained lump that doesn't go away within a couple of weeks should be evaluated.

Yes, many internal cysts, such as those on the kidneys or ovaries, may not cause any symptoms at all. However, larger internal cysts can put pressure on organs, causing various symptoms depending on their location. They are often only discovered through imaging scans.