A lipoma is a slow-growing, fatty lump that’s most often situated between your skin and the underlying muscle layer. A lipoma, which feels doughy and usually isn’t tender, moves readily with slight finger pressure. Lipomas are usually detected in middle age. Some people have more than one lipoma.
A lipoma is a benign (noncancerous) tumor made up of fat tissue. The typical lipoma is a small, soft, rubbery lump located just beneath the skin. They are usually painless and are most often found on the upper back, shoulders, arms, buttocks, and upper thighs. Less commonly, these tumors can be found in deeper tissue of the thigh, shoulder, or calf.
However, people may wish to remove a lipoma that causes pain, complications, or other symptoms. Some people also have concerns about the cosmetic appearance of lipomas.
Lipomas can occur anywhere on the body where fat cells are present, but they tend to appear on the shoulders, chest, trunk, neck, thighs, and armpits. In less common cases, they may also form in internal organs, bones, or muscles.
If you have a lipoma, you are not alone: They are the most common soft tissue tumor found in adults, according to the American Academy of Orthopaedic Surgeons. It’s possible to have more than one lipoma, and they are slightly more likely to occur in men than in women.
A lipoma isn’t cancer and usually is harmless. Treatment generally isn’t necessary, but if the lipoma bothers you, is painful or is growing, you may want to have it removed.
What Is Lipoma?
A lipoma is a round or oval-shaped lump of tissue that grows just beneath the skin. It’s made of fat, moves easily when you touch it and doesn’t usually cause pain. Lipomas can appear anywhere on the body, but they’re most common on the back, trunk (torso), arms, shoulders and neck.
Lipomas are benign soft tissue tumors. They grow slowly and are not cancerous. Most lipomas don’t need treatment. If a lipoma is bothering you, your healthcare provider can remove it with an outpatient procedure.
Types of Lipoma
While all lipomas are made up of fat, there are subtypes based on the way they appear under the microscope. Some varieties include:
- Conventional lipoma (common, mature white fat)
- Hibernoma (brown fat instead of the usual white fat)
- Fibrolipoma (fat plus fibrous tissue)
- Angiolipoma (fat plus a large amount of blood vessels)
- Myelolipoma (fat plus tissue that makes blood cells)
- Spindle cell lipoma (fat with cells that look like rods)
- Pleomorphic lipoma (fat with cells of all different shapes and sizes)
- Atypical lipoma (deeper fat with a larger number of cells)
What Are The Symptoms Of A Lipoma?
There are many types of skin tumors, but a lipoma usually has distinct characteristics. If you suspect that you have a lipoma it will generally:
- be soft to the touch
- move easily if prodded with your finger
- be just under the skin
- be colorless
- grow slowly
Lipomas are most commonly located in the neck, upper arms, thighs, forearms, but they can also occur on other areas such as the stomach and back.
A lipoma is only painful if it compresses nerves underneath the skin. A variant known as angiolipoma is also more often painful than regular lipomas.
You should call your healthcare provider if you notice any changes in your skin. Lipomas can look very similar to a rare cancer called a liposarcoma.
Causes of Lipoma
Doctors do not fully understand what causes a lipoma.
Some people inherit a faulty gene from their parents that can cause one or more lipomas. This is rare and is known as familial multiple lipomatosis.
Lipomas can occur more frequently in people with specific medical conditions, such as:
- Gardner’s syndrome
- Cowden syndrome
- Madelung’s disease
- adiposis dolorosa
Researchers have also suggested that some lipomas may result from an injury that involves a substantial impact on the area.
Providers usually diagnose a lipoma during a physical examination. Your provider will touch the lipoma and ask if it’s painful or tender. You may need a biopsy to confirm that the lipoma isn’t cancer. During this procedure, your provider removes a sample of the lipoma and sends it to a lab for testing.
Oftentimes, these may be mistaken for a cyst. To see a clear picture of this lump, your provider may order an imaging test such as an ultrasound, magnetic resonance imaging (MRI) scan, or computed tomography (CT) scan . These imaging studies help your provider determine if it is a lipoma versus a cyst. It can also help identify the lipoma’s location and how deep it is if it has blood vessels and whether it’s pressing against nerves or other tissues.
Medical History and Physical Examination
Before a physical examination, your doctor will talk with you about your general health, as well as your current condition. He or she will want to get a good history of the problem from your perspective, particularly how long the mass has been there and what symptoms—such as pain—are associated with it.
During the physical examination, your doctor will feel the mass, checking its size and consistency, as well as its mobility. He or she will also examine the skin overlying the mass, looking for any changes.
Although doctors can usually diagnose lipomas based on history and physical examination alone, imaging tests can be helpful for some cases.
X-rays. Although these tests create clear pictures of dense structures like bone, plain x-rays can show a prominent shadow caused by a soft tissue tumor, such as a lipoma.
Computerized tomography (CT) scans. These scans are more detailed than x-rays and will often show a fatty mass to confirm the diagnosis of lipoma.
Magnetic resonance imaging (MRI) scans. The best information for diagnosing lipomas comes from an MRI scan, which can create better images of soft tissues like a lipoma. MRI scanning will show a fatty mass from all perspectives. Oftentimes, doctors can make the diagnosis of lipoma based on MRI imaging alone, and a biopsy is not required.
Biopsy. A biopsy is sometimes necessary to confirm the diagnosis of lipoma. In a biopsy, a tissue sample of the tumor is taken and examined under a microscope. Your doctor may give you a local anesthetic to numb the area and take a sample using a needle. Biopsies can also be performed as a small operation.
In most lipoma cases, a biopsy is not necessary to confirm the diagnosis. After the lipoma is removed, a biopsy will be done on a sample of the tissue.
Under a microscope, lipomas often have a classic appearance with abundant mature fat cells. Sometimes there can be a small amount of other cell types, too, such as cartilage or bone.
Liposarcoma. During the diagnosis phase, your doctor will work to differentiate a lipoma from a more aggressive form of fatty tumor called liposarcoma. Liposarcomas are cancerous. The symptoms of liposarcoma vary from those of lipoma. Liposarcomas typically grow quickly, are often painful, and are not as moveable as lipomas.
People with lipomas are not more likely to develop a fatty cancer in the future. The exception is people with atypical lipomas. This lipoma subtype can turn into a liposarcoma, but this is rare.
A lipoma that’s left alone usually doesn’t cause any problems. However, a dermatologist can treat the lump if it bothers you. They will make the best treatment recommendation based on a variety of factors including:
the size of the lipoma
the number of skin tumors you have
your personal history of skin cancer
your family history of skin cancer
whether the lipoma is painful
The most common way to treat a lipoma is to remove it through surgery. This is especially helpful if you have a large skin tumor that’s still growing.
Lipomas can sometimes grow back even after they’re surgically removed. This procedure is typically done under local anesthesia through a procedure known as an excision.
Liposuction is another treatment option. Since lipomas are fat-based, this procedure can work well to reduce its size. Liposuction involves a needle attached to a large syringe, and the area is usually numbed before the procedure.
Steroid injections may also be used right on the affected area. This treatment can shrink the lipoma, but it doesn’t completely remove it.
When Should I See Doctor
Usually not. If you are not bothered by a lipoma that develops then it is best just to leave it alone. However, some people want lipomas that are unsightly to be removed for cosmetic reasons. For example, if they occur on the face.
Occasionally, a lipoma needs to be removed if it is causing symptoms – for example, by pressing on another part of the body. Sometimes if the diagnosis is not clear, a lipoma is removed to look at under the microscope. This is to make sure the growth that has been detected is a lipoma and not something more serious.
If you have a skin growth, lump or knot under your skin, see your provider. It’s essential to get evaluated and rule out serious conditions, such as liposarcoma (a type of cancer). Symptoms of liposarcoma are similar to signs of a lipoma.
If you have a lipoma, see your provider if you notice any changes, such as sudden pain. Call your provider if it’s growing rapidly (over weeks), feels hard or doesn’t move as easily when you touch it. Your provider will check the lipoma to see if it has blood vessels, which is a sign of a rare type of painful lipoma called an angiolipoma.