A shoulder lump refers to a bump, growth, or mass in your shoulder area. You might feel it rub against clothing or the straps of a bag.

Not all lumps are equal. Some might hurt, while others are painless or cause mild discomfort. The lump might also look pink, white, or the same color as your skin. These traits depend on what’s causing the lump.

While there are many possible causes, most are harmless. But it’s a good idea to visit the doctor if the lump is new, growing, or painful. You should also seek emergency help if you were recently injured.

In this article, we’ll discuss the potential reasons for shoulder lumps, along with symptoms and treatments.

The causes of shoulder lumps vary in type and severity. To determine what you might have, take note of other symptoms.

Lipoma

A lipoma is a lump of fat tissue underneath the skin. It’s a benign (noncancerous) soft tissue tumor. Scientists don’t know why they occur.

Lipomas are common. About 1 in every 1,000 people have one. Often, lipomas show up on the shoulders, trunk, neck, and armpits.

They’re usually:

  • rubbery, soft, and doughy
  • movable
  • usually less than 2 inches, but may be bigger
  • occasionally painful

Usually, the lipoma itself doesn’t cause pain. But if it presses on nerves or has blood vessels, it can hurt.

Cyst

Your shoulder lump might be a cyst, or a closed sac of tissue. Depending on the type of cyst, it might contain air, pus, or fluid. Cysts are usually benign.

There are many kinds of cysts. But some types can appear on the shoulder, including the following:

  • Epidermoid cyst. An epidermoid cyst, also called a sebaceous cyst, is a painless flesh-colored sac under the skin. It’s filled with a protein called keratin, a thick, yellowish material that may drain from the bump.
  • Paralabral cyst. This cyst contains joint fluid and develops around the shoulder joint. While it’s usually painless, it can hurt if it presses against nearby nerves or tears the surrounding cartilage.
  • Ganglion cyst. Ganglion cysts usually form on the hands or wrists, but in rare cases, they can occur near other joints, like the shoulders. A ganglion cyst is often round or oval and painless.
  • Bone cyst. A bone cyst is a fluid-filled pocket in the bone. It usually isn’t painful, though it can get big enough to cause a fracture.

Abscess

Another cause is a skin abscess, or a pus-filled lump deep under the skin. It’s typically caused by a bacterial infection.

An abscess might look like a big pimple. Other symptoms include:

  • round shape
  • firm, yet squishy
  • pain
  • redness
  • pus draining from the center
  • warm to the touch

Since an abscess is caused by a bacterial infection, you may also have a fever and chills.

Trauma or injury

A shoulder lump can form after hurting your shoulder. Potential causes include:

  • Fracture. A shoulder fracture, or broken shoulder, involves a break in one of your shoulder bones. Symptoms include pain, swelling, and a lump where the bone broke.
  • Separation. A separated shoulder occurs when the ligaments between the collarbone and shoulder blade tear. The shoulder blade can move downward, which forms a bump on top of your shoulder.
  • Muscle contusion. A muscle contusion, or an injury to the muscle fibers, causes swelling and bluish discoloration. If blood collects within the tissue, it can form a bump called a hematoma.

Muscle knot

A muscle knot is a group of tense muscle fibers. It happens when muscle tissue contracts, even when you’re relaxing.

Also called myofascial trigger points, muscle knots can affect any part of the body. They commonly form on the neck and shoulders.

Symptoms include:

  • aching and pain
  • sensitivity when touched
  • hardness
  • swelling

Muscle knots are often caused by inactivity or overuse. Regular exercise and therapeutic massages can help get rid of them.

Large pimple or wart

Your shoulder lump might be a big pimple or wart. These skin conditions are usually harmless, though they can cause discomfort and pain.

Pimples, or acne, happen when your pores are clogged with oil and dead skin cells. They often form on the shoulders, face, upper back, and chest.

Larger pimples are most likely:

  • Cystic acne. Cystic acne are painful bumps filled with pus. They form underneath the skin.
  • Nodular acne. Nodules are harder lumps. Like cystic acne, they develop beneath the skin and are painful.

On the other hand, warts are caused by a human papilloma virus (HPV) infection. They usually show up on the hands, but they can appear anywhere, including the shoulders.

Warts might be:

  • small or big
  • rough or smooth
  • white, brown, pink, or flesh-colored
  • itchy

Arthritis

Arthritis, or joint inflammation, can lead to shoulder lumps. The characteristics of the lump will depend on the kind of arthritis you have.

Rheumatoid arthritis (RA), a type of autoimmune arthritis, can cause rheumatoid nodules. These nodules form under the skin and usually appear on bony areas, like the shoulders.

A rheumatoid nodule can be as big as a lemon. They are:

  • flesh-colored
  • hard or dough-like
  • movable or connected to underlying tissue

Osteoarthritis (OA), or degenerative arthritis, can cause bone spurs called osteophytes. These bony lumps grow around joints affected by osteoarthritis.

Osteophytes often appear on the shoulders, neck, knees, fingers, and feet. They don't always cause symptoms. If a lump presses against nerves or other tissues, you may have pain or loss of joint motion.

Cancer

A shoulder lump might indicate soft tissue sarcoma. This is a rare cancer that forms a tumor in the connective tissue, including the muscle, tendons, and nerves.

The tumor is typically painless. It most often affects the:

  • shoulders
  • thighs
  • pelvis
  • abdomen
  • chest

As the tumor progresses, it may cause pain and restrict your movement.

Squamous cell carcinoma, as type of skin cancer, can also cause shoulder lumps. These bumps are rough scaly patches that may look like warts.

The location of your shoulder lump can tell you more about the cause.

Lump on shoulder blade

A lump on your shoulder blade might indicate a fracture or separated shoulder.

Lump on shoulder bone

The shoulder bones include several bones, including the shoulder blade. Bumps in this area might be caused by:

  • separated shoulder
  • fracture
  • rheumatoid nodule
  • osteophyte
  • bone cyst

Shoulder lump under skin

Typically, a shoulder lump under the skin’s surface is a:

  • lipoma
  • cyst
  • cystic or nodular pimple
  • abscess

Shoulder lump on the skin

If the lump is on the skin’s surface, it might be a:

  • non-cystic pimple
  • wart
  • squamous cell carcinoma tumor

Lump on shoulder muscle

Possible causes of shoulder muscle lumps include:

  • muscle contusion
  • muscle knot
  • soft tissue sarcoma

Most causes of shoulder lumps are painful or uncomfortable. However, the following causes are typically painless:

  • lipoma
  • cyst
  • rheumatoid nodule
  • osteophyte
  • warts
  • cancerous tumor

In general, the above lumps only cause pain when they put pressure on nearby nerves or tissue.

Most lumps aren’t serious. But if the shoulder lump doesn’t go away in 2 weeks, it’s best to visit a doctor.

You should also seek medical help if the lump:

  • gets bigger
  • hurts
  • doesn’t move
  • comes back after it’s removed

If you were recently injured, get medical attention immediately. You might have a serious injury, like a broken bone.

To diagnose your shoulder lump, a doctor might use a:

  • Physical exam. A doctor will examine the lump by touching it. They’ll also look for other symptoms, like redness and swelling.
  • MRI scan. An MRI uses radio waves to take an image of soft tissues.
  • X-ray. If a doctor thinks the lump is on your bone, they’ll have you get an X-ray.
  • CT scan. A CT scan takes X-rays at multiple angles.
  • Biopsy. If a doctor suspects a lipoma or tumor, they might request a biopsy. A sample of tissue from the lump will be examined in a lab.

Because there are many causes of shoulder lumps, there are many possible treatments. The appropriate method depends on the condition.

Some options include:

  • Surgical removal. Some lumps can be surgically removed. This is best for conditions like lipomas, cysts, warts, and rheumatoid nodules.
  • Drainage. Drainage is useful for lumps like abscesses, cysts, and hematomas.
  • Prescription medication. If you have cystic acne, the doctor can prescribe topical or oral medication. They can also prescribe medication to shrink rheumatoid nodules.

Minor causes of shoulder lumps usually don’t need treatment.

Shoulder lumps can vary in size. Depending on the cause, the lump might feel hard, doughy, smooth, or rough. It may or may not be painful.

Generally, shoulder lumps aren’t a cause for concern. Most lumps go away on their own. But if your lump keeps growing, or if it doesn’t go away in 2 weeks, see a doctor. You should also seek medical help if it hurts or causes discomfort.