Lump on Shoulder: What It Could Be

What causes a lump on the shoulder

Most shoulder lumps come from the skin, the fat just under it, or the joint structures around the shoulder. The feel of the lump and its exact position are the best early clues.

Lipoma

A lipoma is the commonest shoulder lump in adults. It is a benign collection of fat cells wrapped in a thin capsule. The shoulder, upper back, neck and upper arm are favorite sites.

• Feels soft, doughy or rubbery
• Slides a little under your fingers
• Usually painless, and grows slowly over months or years
• Most are 1 to 5 cm across, though some grow larger

Lipomas are harmless and do not turn into cancer. A very large, deep or fast-growing "lipoma" is still worth imaging, because a liposarcoma can look similar.

Skin cysts (epidermoid and sebaceous cysts)

A cyst is a closed sac under the skin filled with keratin, a cheesy material. On the shoulder and upper back these are often called sebaceous cysts, although most are technically epidermoid cysts.

• Round, smooth and firm, attached to the skin
• Often has a tiny dark dot (punctum) on top
• Can become red, swollen and painful if it gets inflamed or infected, and may leak a foul-smelling paste

The "shoulder bump" at the top of the shoulder

A visible bony bump where the collarbone meets the tip of the shoulder is usually the end of the collarbone sitting higher than normal after an AC joint separation. It follows a fall onto the point of the shoulder, common in cycling, rugby, football and skiing.

Once healed, the bump is mostly cosmetic. Many people asking whether a big shoulder bump "will cause problems" can be reassured: most mild and moderate separations (grades I to III) regain normal strength and movement without surgery, even when the bump stays. Ongoing pain, clicking or weakness with overhead lifting can develop in some people, and arthritis of the AC joint can cause a bony bump later in life too. Those cases are assessed for physical therapy, injections or, occasionally, surgery.

Bursitis

A bursa is a small fluid-filled cushion that reduces friction. Inflamed bursae can swell, especially over the back of the shoulder blade (scapulothoracic bursitis) or on top of the shoulder. Bursitis feels like a soft, tender, squashy swelling and is often linked to repetitive overhead movements or a direct knock.

Abscesses and boils

A boil or abscess is a pocket of pus, often caused by Staphylococcus aureus. It is red, hot, tender and gets bigger over a few days, sometimes forming a yellow head. It is not subtle, and it usually needs draining if it is larger than a pea.

Swollen lymph nodes

The shoulder area has no large lymph node groups of its own, but swollen nodes in the armpit or just above the collarbone can be felt as a "shoulder lump". Nodes that are tender and appear with an infection usually settle within 2 to 3 weeks. Swollen lymph nodes above the collarbone (supraclavicular nodes) are always worth checking, because they are more often linked to cancer in the chest or abdomen.

Bone lumps

• Osteochondroma: a benign bony outgrowth, usually found in teenagers and young adults near the growth plates of the upper arm bone (humerus). It feels rock-hard and does not move.
• Healed fracture: a broken collarbone often leaves a firm bony lump (callus) along the bone for months.
• Bone tumors: rare. Deep, constant bone pain that is worse at night is more typical than a lump.

Soft tissue sarcoma and other cancers

Soft tissue sarcoma is a rare cancer of fat, muscle or connective tissue. On the shoulder it usually shows up as a painless lump that keeps growing, is deep to the muscle and is often larger than 5 cm when found. Skin cancers such as melanoma can also appear on sun-exposed shoulder skin as a changing dark spot or nodule.

Lump on shoulder: how to tell the common causes apart

Lump on the right or left shoulder

The side does not change the likely causes. A lump on your right shoulder is no more or less worrying than one on the left. What matters is the lump itself: its size, depth, hardness and whether it is changing. If you are right-handed you may notice a right-sided lump sooner, or have more overuse bursitis on that side.

When to worry about a shoulder lump

Doctors use a few simple rules to decide which lumps need imaging. Get your lump checked if it:

• is bigger than a golf ball (about 5 cm or 2 in)
• is growing, or has appeared in the last few weeks and is not shrinking
• feels hard and does not move, or sits under the muscle
• comes back after being removed
• comes with unexplained weight loss, night sweats or fevers
• is a dark, irregular or changing spot on the skin

Pain is not a reliable warning sign. Many sarcomas are painless, while infected cysts and bursitis can be very sore.

How doctors diagnose a shoulder lump

Your doctor will ask how long the lump has been there, whether it has changed, whether you injured the shoulder, and about fever, weight loss and night sweats. They will examine the lump for size, texture, depth and tenderness, check the armpit and neck for lymph nodes, and test shoulder movement and arm strength.

Tests depend on what the lump looks like:

• Ultrasound: the first test for most soft lumps. It shows whether a lump is a cyst, fat or fluid, and how deep it lies.
• X-ray: for bony lumps, an AC joint bump or a suspected fracture.
• MRI: for deep, large or unusual lumps, and before surgery.
• Biopsy: a needle sample, done at a specialist sarcoma center if a sarcoma is possible.
• Blood tests: if infection, lymphoma or another general illness is suspected.

Treatment for a lump on the shoulder

Treatment depends on the cause:

• Lipomas and small cysts can be left alone if they cause no trouble. They can be removed under local anesthetic if they are painful, growing, catch on straps or bother you cosmetically.
• Inflamed cysts may settle with warm compresses. Infected cysts and abscesses usually need to be cut open and drained. Antibiotics are added if the skin around is spreading red. The cyst wall is removed later, once things calm down, to stop it coming back.
• Bursitis is treated with rest from aggravating movements, ice and anti-inflammatory painkillers (follow the label dose, and avoid NSAIDs if you have kidney disease, stomach ulcers or take blood thinners), physical therapy and sometimes a steroid injection.
• AC joint bumps rarely need treatment. Physical therapy restores strength. Surgery is reserved for severe separations or ongoing pain.
• Sarcomas and other cancers are treated at specialist centers with surgery, often with radiotherapy.

Do not try to squeeze or lance a lump yourself. It can push infection deeper and leave a worse scar.

Frequently asked questions

What causes a lump on the shoulder?

The commonest causes are lipomas (soft fatty lumps), skin cysts, bursitis, abscesses and a bony bump from an old AC joint injury. Less common causes include swollen lymph nodes, bony growths such as osteochondroma and, rarely, soft tissue sarcoma. The lump's feel, size and growth pattern point to which one it is.

Will a big shoulder bump cause problems?

A bony bump at the top of the shoulder after an AC joint separation is usually only cosmetic. Most people regain full strength and movement with physical therapy. A minority develop pain with overhead or heavy lifting, or arthritis in the joint later. See an orthopedic specialist if the bump hurts, clicks or limits what you can do.

Is a hard lump on the shoulder cancer?

Usually not. Hard lumps are often bone (an AC joint bump, a healed collarbone fracture or an osteochondroma) or a firm skin cyst. A hard lump that is growing, fixed to deeper tissue or larger than 5 cm should be checked with an ultrasound or MRI, because these features raise the chance of a sarcoma.

Can a shoulder lump come from muscle strain?

A muscle knot or a tear can feel like a firm, tender area, and bleeding into the muscle after an injury can form a lump (a hematoma). These usually shrink over 2 to 6 weeks. A lump that stays firm or grows after a muscle injury should be imaged, as a rare bone-forming reaction called myositis ossificans can develop.

Should I get a soft lump on my shoulder removed?

You do not have to. A soft, movable, slowly growing lipoma or cyst can safely be left alone. Removal is reasonable if it is painful, keeps getting inflamed, is growing, or you dislike how it looks. Any lump that is growing quickly or is larger than 5 cm should be imaged before removal.

What kind of doctor should check a shoulder lump?

Start with your primary care doctor, who can examine it and arrange an ultrasound. Depending on the result, you may be referred to a dermatologist for skin lumps, an orthopedic surgeon for bone and joint lumps, or a sarcoma specialist center for anything suspicious.