Hard Lump Under Skin: Causes and Symptoms to Look Out For

By Robynn Lowe
Medically reviewed checkmarkMedically reviewed
August 25, 2022

Finding a hard lump under your skin might be alarming, but try to stay calm—there are many causes of such a lump, and most are usually harmless.

Many of these lumps may not require treatment, and even when they do, they are often not severe cases. The more information you have, the calmer a decision you can make about seeking treatment.

In this article, I’ll discuss the common and severe causes of hard lumps under the skin. I’ll explain how to evaluate these lumps and the symptoms to look out for. I’ll also talk about cancerous lumps.

Finally, I’ll explore the possible treatment options, and when to see a medical professional.

Common Causes of Hard Lump Under Skin

Several medical conditions can cause hard lumps under the skin. Some are mild conditions that may not require medical attention, while some will require immediate treatment, so it does not worsen. The common conditions that fall into this category do not usually require medical attention. 

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Epidermoid cysts

Epidermoid cysts are commonly called sebaceous cysts, even though they do not involve the sebaceous gland. They are small lumps under the skin filled with keratin.

They are typically harmless, though new evidence suggests they may develop into a new occurrence of cancer in the body. Epidermoid cysts are commonly found on the face, neck, and trunk, but can also be found anywhere else in the body.

Epidermoid cysts are rarely found in people younger than 30 years old, and are more common in people without vaginas.


Lipoma is a small hard lump under the skin made of fat. They can be anywhere in the body, but are more commonly found in the back, trunk, arms, shoulder, and neck.

They are typically harmless. They move when touched, and often, people can have more than one. Lipomas are quite common, especially during ages 40-60, though they can happen at any age.

They occur more in people with vaginas. Doctors are unsure of the exact cause, but possible causes include physical trauma after an injury, inherited from family, or medical conditions such as Madelung disease, Gardner’s syndrome, adiposis dolorosa (Dercum’s disease), and hereditary multiple lipomatosis.


Dermatofibromas are small, hard bumps that grow under the skin. They are typically harmless, but may cause itching and mild pain. While many people have one dermatofibroma, it is possible to have multiple.

It occurs commonly in people with vaginas. The exact cause is unknown, but suggested possibilities include trauma to the skin, splinters, and insect bites. 


A keratoacanthoma is a dome-shaped lump that grows on your skin. Experts suggest that it may be linked to sun damage, since it is commonly found in areas regularly exposed—like the face, neck, hand, and leg.

It is noncancerous, but can resemble squamous cell carcinoma, and should be checked by a doctor immediately.                                                                      


Pilomatricoma, also spelled as pilomatrixoma, is an uncommon skin lump related to hair follicles. It occurs mainly on the head and neck, but can also be found on the arms and legs. Pilomatricoma usually happens to individuals younger than 20, but can also occur at a later age.

It is typically noncancerous, but there are rare cases where the lump is cancerous, called pilomatrix carcinoma. This occurs most commonly in individuals aged 50 and above. People usually have one pilomatrixoma, but it is possible to have multiple.

This is especially associated with conditions like Gardner’s syndrome, myotonic dystrophy, and Rubinstein-Taybi syndrome.

Swollen lymph node

Lymph nodes are a group of cells in the body that swell in response to viral or bacterial infection. Blood cells gather to fight the infection and exert pressure, which causes swelling. Lymph nodes are located in various parts of the body. 

Lymph nodes will usually return to their usual size once the infection clears. If the lymph nodes swell suddenly with no apparent cause, keep swelling, remain for 2-4 weeks, or do not move when you push them, see a doctor immediately. It may be a sign of a more severe condition. 

More Severe Causes of Hard Lump Under Skin

While hard lumps will usually not need treatment, some may require immediate medical attention.


A hernia occurs when an organ or tissue pushes through an abnormal opening. It is generally caused by both the pressure of the organ and weakness or opening of the surrounding muscle.

Most hernias happen between the chest and the hips. There are several types of hernias. If you self-diagnose a hernia, which is usually the case, seek medical attention immediately.

Evaluation and Symptoms to Look Out For

If you notice a hard lump under your skin, look out for the following symptoms to determine the kind of lump.

Epidermoid cyst

  • Small lump under skin
  • Tiny black head at the center of the cyst
  • Grows slowly
  • Might release thick yellow discharge with bad smell
  • Usually painless, but become red and tender when infected


  • Round or oval-shaped lump
  • Grows slowly
  • Moves easily when touched
  • Usually painless, except if it is pressing against a nerve or contains blood vessels
  • Usually about 2 inches in diameter, but can grow up to 5 inches


  • Occurs commonly on the thighs or leg
  • May cause occasional itching and mild pain
  • Usually about 1 cm in diameter
  • Can be red or brownish


  • May itch or be painful
  • Grows rapidly up to 3 cm in diameter
  • Has keratin as the tough plug at the core of the lesion
  • Common among light skinned people
  • Common among adults


  • Usually a single, firm lump
  • Slight discoloration of the lump area
  • Occurs commonly on the head and neck 
  • May cause pain if the lump puts pressure on other structures
  • Common in children and adolescents

Swollen lymph node

  • Swelling in sides of neck
  • Swelling in armpit
  • Swelling in groin
  • Swelling under your chin

Swelling usually occurs close to the site of infection, but if there is more than one swollen node site, it is likely an infection affecting the entire body.


  • Bulge that can be pushed back in
  • Swelling
  • Pain at the site of bulge
  • Increase in the size of bulge over time
  • Burning sensation
  • Dull ache
  • Sense of feeling full 
  • Signs of bowel obstruction

A doctor or healthcare provider can evaluate the lump to determine its type. They may press it to feel how hard or tender it is. They may also ask if it is painful or require a biopsy to confirm the diagnosis.

Cancerous Lumps Guide

A hard lump under the skin is rarely caused by cancer, but here are some features to note about cancerous lumps:

  • Hard
  • Painless
  • Changes color
  • Changes in size, usually rapidly
  • Immovable when pushed on
  • Appears suddenly
  • Does not disappear after a while

Cancerous lumps that are noticeable are typically found in the breast, neck, testicle, arm, and leg.

Possible Treatment Options

Epidermoid cyst

The treatment of epidermoid cyst may involve surgery to remove the entire cyst, injecting the cyst with a medicine to reduce the swelling, or making a cut on the cyst and draining the contents. 


Lipomas are typically harmless, but they can become uncomfortable. Your doctor can perform surgery to remove the lump. The surgical procedure requires only local anesthesia and is quick enough that you can still leave the hospital on the same day. 

Liposuction is another option involving using a needle and syringe to remove the lump, though it is less frequently used because it is highly likely to reoccur. Steroid injections are also used, though this method only shrinks them.


If the dermatofibroma becomes enlarged or causes pain and itching, it can be surgically removed.


Keratoacanthoma is harmless, and does not need any treatment. It will usually go away on its own, but surgery and medication can speed up the process.


Pilomatricoma can be removed surgically, and usually does not recur after surgery.

Swollen lymph node

The treatment a person will need for swollen lymph nodes depends on the cause of the swelling. If it is a common bacterial or viral infection, your doctor may prescribe an antiviral or antibiotic drug to clear it. 

In rare cases, swollen nodes are caused by lupus, syphilis, measles, or lymphoma. These conditions require specific treatment plans that may span several weeks or months.


Your doctor may choose first to monitor the situation. Surgery may be needed to return the tissue or organ to its normal position and close the abnormal opening.

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When to See a Medical Professional 

Hard lumps are usually harmless, but in rare cases, may be a symptom of a serious condition. 

See a medical professional if you notice:

  • A lump that is hard, painless, and immovable
  • Pain around the lump area
  • Rapid enlargement of the lump
  • Change in color and shape of the lump
  • High fever
  • Pus leaking from the lump

Your doctor may perform a skin biopsy to confirm the diagnosis, which will inform their treatment options.

How K Health Can Help 

If you’ve noticed a spontaneous hard lump under your skin, it may be time to speak to a doctor. Did you know you can get affordable primary care with the K Health app?

Download K Health to check your symptoms, explore conditions and treatments, and if needed text with a clinician in minutes. K Health’s AI-powered app is based on 20 years of clinical data.

Frequently Asked Questions

Are cancerous lumps hard or soft?
Cancerous lumps are usually hard to the touch. They are often large, immovable, and painless.
How do you get rid of a hard lump under your skin?
Getting rid of a hard lump under your skin depends on the cause of the lump. If the hard lump is sudden, and you do not remember hitting that part of your body, you may need to have your doctor check it out. However, if it is caused by physical injury, rest the injured part. You can also apply an ice pack and elevate the affected area.
How do you tell if a lump is a tumor?
A lump is likely a tumor if it is firm, because tumors are solid masses of tissue. Tumors do not typically produce yellow, white, or green discharge, and do not move under the skin.
K Health articles are all written and reviewed by MDs, PhDs, NPs, or PharmDs and are for informational purposes only. This information does not constitute and should not be relied on for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment.

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Robynn Lowe

Robynn Lowe is a board certified Family Nurse Practitioner with over 15 years in the medical field. Robynn received her Bachelor's and Master's degrees from Florida Atlantic University and has been practicing in rural family medicine since. Robynn is married to her college sweetheart, Raymond and they have three awesome children. When Robynn isn't with patients you can find her shopping, coaching her kids sports teams, or spending time on the water.