Painless Thigh Lump: Top Causes
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Finding a painless thigh lump can be concerning, however most lump on the thigh are caused by non cancerous fatty tissue growth, also known as lipoma, or skin conditions like warts, cysts, or abscess. Swollen lymph nodes may also cause painless lumps on the inner thigh.
Symptoms of a painless knot on the thigh
A new or persistent lump anywhere on your body can be alarming. The good news is that there are many potential causes for painless thigh lumps, and most of these causes are not serious or difficult to treat. Sometimes, however, a painless thigh lump may require evaluation by a medical professional either for treatment or a diagnosis.
Common characteristics of painless thigh lumps are
Depending on their cause, painless thigh lumps may be:
- Large or small
- Soft or firm
- Single or multiple
- Mobile: This means it moves when you touch or press it.
- Fixed: This means it feels stuck in its location.
Common accompanying symptoms are
Painless thigh lumps can also be associated with:
- Skin that feels hot to the touch in the area of the lump
The length of time that you may experience a painless thigh lump can vary.
- Temporary: Depending on the cause, a thigh lump may last for only a few days before resolving on its own or you may notice it persist for a week or more.
- Persistent: You may notice that a thigh lump that is persistent seems to grow over time as well.
- How to monitor: When monitoring your thigh lump, keep track of its size and color and any associated symptoms.
What causes a painless lump on the thigh?
There are many potential causes for painless thigh lumps. Painless thigh lumps can be a symptom of abnormal growths or a reaction to injury.
Typically, a painless thigh lump is caused by abnormal growth of a variety of different cells that make up your body. These can include:
- Fat cells: These can grow into lumps called lipomas.
- Keratin collections: Thigh lumps can also be caused by a collection of keratin, the main protein in your skin, which can lead to cysts.
- Connective tissue cells: Some cells in your body are responsible for rebuilding tissue after injury. These cells can also abnormally grow or reproduce to form thigh lumps called dermatofibromas.
Thigh lumps may also be caused by damage to your thigh. You may have recently bumped or otherwise injured the area and noticed a swelling form afterward. This swelling is formed by blood or fluid collecting under the skin of your thigh and can be associated with bruising and tenderness.
Skin infections or those within the body due to bacteria, viruses or fungi can cause a painless thigh lump, though more often than not, infections usually cause painful thigh lumps.
- Viral skin infections: Viruses can cause painless thigh lumps in the form of skin-colored warts.
- Fungal skin infections: Fungi can cause a variety of painless skin infections, including ringworm, which causes an itchy, red, circular rash that may have an associated lump.
- Bacterial skin infections: Your skin is covered in hair follicles, tiny sacs from which each strand of hair grows. Sometimes a hair follicle can become infected by bacteria which leads to something called folliculitis. An open cut, if exposed, can also become infected leading to something called cellulitis, an infection of the skin and area under the skin. A skin infection that isn’t cleared up can lead to an abscess, which is a pocket of pus that forms as your body tries to fight the infection. These bacterial infections usually cause painful thigh lumps, but early on in the infectious process, they may be painless.
- Lymph node enlargement: Lymph nodes are small glands where the cells that fight infections live. In reacting to infection caused by bacteria, fungi or viruses in and around the area, lymph nodes can grow in size and appear as single or multiple lumps under your skin.
This list does not constitute medical advice and may not accurately represent what you have.
Lipoma is a word that translates as "fatty tumor," but a lipoma is not cancer. It is simply a growth of fat between the muscle layer and the skin above it.
The exact cause is not known. The condition does run in families and is associated with other unusual syndromes such as adiposis dolorosa, which is similar. Lipomas most often appear after age 40.
Symptoms include a soft, easily moveable lump beneath the skin, about two inches across. A lipoma is painless unless its growth is irritating the nerves around it. They are most often found on the back, neck, and abdomen, and sometimes the arms and upper legs.
It is a good idea to have any new or unusual growth checked by a medical provider, just to make certain it is benign.
Diagnosis is made through physical examination, biopsy, and imaging such as ultrasound or CT scan.
Most of the time, treatment is not necessary unless the lipoma is unsightly or is interfering with other structures. It can be removed through surgery or liposuction.
Top Symptoms: skin-colored groin bump, marble sized groin lump, small groin lump
Symptoms that always occur with lipoma: skin-colored groin bump
Urgency: Wait and watch
A cyst is a small sac or lump, filled with fluid, air, fat, or other material, that begins to grow somewhere in the body for no apparent reason. A skin cyst is one that forms just beneath the skin.
It's believed that skin cysts form around trapped keratin cells – the cells that form the relatively tough outer layer of the skin.
These cysts are not contagious.
Anyone can get a skin cyst, but they are most common in those who are over age 18, have acne, or have injured the skin.
Symptoms include the appearance of a small, rounded lump under the skin. Cysts are normally painless unless infected, when they will be reddened and sore and contain pus.
Diagnosis is made through physical examination. A small cyst can be left alone, though if it is unsightly or large enough to interfere with movement it can be removed in a simple procedure done in a doctor's office. An infected cyst must be treated so that the infection does not spread.
Top Symptoms: skin-colored armpit bump, marble sized armpit lump, small armpit lump
Symptoms that always occur with skin cyst: skin-colored armpit bump
Urgency: Wait and watch
Warts, also called common warts or verrucae, are small, rough, rounded growths on the top layer of the skin. They may appear alone or in clusters. Common warts are caused by the human papillomavirus (HPV) and are contagious through direct contact. They may spread from one place on the body to another simply through touch.
Cancer of fat cells
Liposarcoma is a type of cancer characterized by tumors growing in fatty tissues. This cancer can occur in any part of the body, but most often involves the thigh or the belly (abdomen).
Rarity: Ultra rare
Top Symptoms: fatigue, unintentional weight loss, abdominal bump, hard palpable mass, painless abdominal lump
Symptoms that always occur with cancer of fat cells: lump below the skin on the chest
Urgency: Primary care doctor
Enlarged lymph nodes in the groin
Enlarged lymph nodes occur when the node becomes larger as it fills with inflammatory cells. This often is a result of an infection but can occur without a known cause.
Top Symptoms: groin lump, movable groin lump
Symptoms that always occur with enlarged lymph nodes in the groin: groin lump
Symptoms that never occur with enlarged lymph nodes in the groin: fever, unintentional weight loss, hard groin lump
Urgency: Phone call or in-person visit
When and how to treat a painless knot on the thigh
There are certain at-home remedies you can try to alleviate symptoms of painless thigh lumps.
- Infection: If your thigh lump is due to an infectious cause, warm and cold compresses and over-the-counter painkillers can prevent them from getting worse or from becoming painful.
- Abnormal growth: If your thigh lump is due to abnormal cell growth you should have it evaluated by a medical provider. He or she can recommend any further workup of the thigh lump if needed.
When to see a doctor
While some painless thigh lumps resolve without treatment or can be treated with at-home remedies, some require evaluation by a medical professional in the coming days, especially if you notice any of the following:
- Redness that is worsening or spreading around the lump
- Change in shape, size, or color of a thigh lump over time
Medical tests and treatments
The following are medical treatments or diagnostic tests your medical provider may recommend:
- Ultrasound, X-ray, CT Scan or MRI: These are all various methods to gather images of the affected body part before moving on to more invasive tests, if indicated.
- Blood tests: Your medical provider may recommend getting blood tests which may reveal whether your thigh lump is due to an infection or if abnormal growths are causing lymph node enlargement.
- Surgery: If the thigh lump is caused by an abnormal growth of cells (tumor), a physician may recommend surgery to remove the lump to assess what kind of cells are causing the growth and whether the growth is cancerous or not. Sometimes this surgery happens after a biopsy, during which a small sample of the lump is cut out and a pathologist looks at the sample under a microscope to determine whether the abnormal cells are cancerous or at risk of becoming cancerous.
- Incision and drainage: If your thigh lump is caused by an infection that has led to a collection of pus under your skin, a medical professional may need to cut a small hole (incision) in the skin overlying the lump in order to drain the pus collection.
- Antibiotics or antifungals: You may also be prescribed an antibiotic or antifungal in pill or cream/ointment form in order to fight the infection if the thigh lump is due to a bacterial or fungal cause.
When it is an emergency
You should seek immediate medical attention if your painless thigh lump is associated with any of the following symptoms or factors:
- Severe, sudden, or worsening pain and/or swelling
- Nausea and/or vomiting
FAQs about painless thigh lump
Why is my thigh lump becoming painful?
The pain you’re feeling depends on the cause of the thigh lump. Thigh lumps caused by infection may be painful because the body’s immune response is reacting to the infection, and one of the symptoms of this reaction is pain to alert you that something is wrong. If your thigh lump is due to trauma, the pain you’re feeling is most likely the aftermath of the damage to the area in and around the lump. If your pain doesn’t get any better or gets worse, seek the attention of a medical provider.
Will my thigh lump go away on its own?
It depends. If your thigh lump is due to abnormal cell growth, it might stay the same, grow, or shrink. If it is caused by infection, it might go away on its own as your body fights the infection or might go away with some over-the-counter anti-inflammatory medication NSAIDs like ibuprofen (Advil, Motrin). If the infection has caused a collection of pus (an abscess) to form, it might go away, but typically this requires draining by a medical professional. Any lump that persists or grows over time should be seen by a medical provider.
Why is my thigh lump growing?
Your thigh lump may be growing due to fluid or blood collecting in and around the area of the lump. If your thigh lump is due to trauma, you can often get swelling around the injured area, but this swelling should decrease over time. A thigh lump due to infection may grow as pus collects in the lump under the skin or as lymph nodes enlarge in reaction to the infection. A thigh lump can also grow if abnormal cells or protein (like keratin) are building up. These cells can either be cancerous or non-cancerous. A thigh lump that is growing rapidly in size, persistently grows, or is associated with a change in color or shape should be medically evaluated.
Is my thigh lump a sign of cancer?
Rarely, a painless thigh lump may be a sign of cancer. Thigh lumps due to cancer are usually in the area of the groin and represent swelling of the lymph nodes which can occur as a reaction to cancer or due to cancer within the lymph nodes themselves. If your painless thigh lump is associated with fevers, chills, night sweats or unexplained weight loss, it may be due to cancer and you should be evaluated by a medical provider.
Is my painless thigh lump serious?
A small thigh lump that resolves on its own is typically not serious. A large thigh lump that is associated with redness or that does not seem to be resolving should be seen by a medical professional, especially if you also have a fever. Thigh lumps that are growing and feel fixed may be serious and/or a sign of cancer and should be evaluated by a medical professional.
Questions your doctor may ask about painless thigh lump
- What color is the bump?
- Do you have a rash?
- Any fever today or during the last week?
- Are you experiencing a headache?
Self-diagnose with our free Buoy Assistant if you answer yes on any of these questions.
Dr. Maina graduated from Princeton University (BA, 2013) with a degree in psychology and received her medical degree from the University of Pennsylvania Perelman School of Medicine. She is currently a resident physician in Otolaryngology at the University of Pennsylvania affiliated hospitals. After graduating from Princeton, she spent a year researching embryonic gene expression with the Center for Research on Reproduction and Women's Health at UPenn. She also received a grant from the National Institutes of Health to study abnormal innate immune responses and taste-related genes in chronic sinus infections. In her free time, she enjoys cooking, reading, listening to podcasts, and finding new DIY décor projects.
- Cysts. American Osteopathic College of Dermatology. AOCD Link
- Dermatofibroma. Genetic and Rare Diseases Information Center. Updated March 19, 2017 GARD Link
- Ringworm. American Academy of Dermatology. AAD Link
- Folliculitis and carbuncles. Massachusetts General Hospital. Mass General Hospital Link
- Cellulitis. U.S. National Library of Medicine: MedlinePlus. Updated June 6, 2018. MedlinePlus Link
- Abscess. U.S. National Library of Medicine: MedlinePlus. Updated June 6, 2018. MedlinePlus Link