A lump on the shoulder or upper arm is a common problem that may be caused by a number of different things.
Shoulder lumps may be the result of an injury such as a fall or an MVC which may have broken or dislocated one of your bones.
Or the lump on your shoulder may be from inflammation such as bursitis or a cyst. It may be a small, soft, mobile lump or a large, hard painful lump.
And what people tend to worry about most is that they may have a cancer lump on their shoulder, but that is very rare and in most cases, a lump on the shoulder will settle down within a few weeks.
Here we will look at the most common causes of lumps on shoulders, how to work out which one you have, how to treat them and what signs to watch for in case something serious is going on.
If you have injured your shoulder through some sort of collision e.g. fall, sports or car accident and there is a lump on your shoulder, you may have broken one of the shoulder bones. Shoulder lumps from fractures can occur in the:
The shoulder lump from a fracture may appear:
A lump on the shoulder from a fracture will usually be very painful, particularly if you touch it. Depending on the severity of the break, it may be left to heal naturally, you may need to wear a sling, or surgery may be advised.
Find Out More: Shoulder Fractures
A shoulder lump after a traumatic event may indicate a dislocation rather than a fracture. A dislocation is where one of the bones pops out of its usual place in the joint resulting in an obvious deformity. There are two types of dislocation that can cause a lump on the shoulder:
A lump in an arm muscle after direct impact may indicate muscle damage rather than a broken bone. With a muscle contusion the muscle fibres are injured due to blunt force trauma, causing swelling and sometimes a bruise with a lump on the shoulder muscle or in the upper arm.
In some cases a haematoma may form (a collection of blood) causing a hard lump in the arm muscle. Whilst it may be uncomfortable for a while, a shoulder or arm contusion usually heals quickly with home treatment.
A soft fatty tissue lump on the shoulder is often a lipoma, a non-cancerous tumour where a fatty mass forms underneath the skin. Lipomas are common affecting around 1 in a 1000 people, usually between the ages of 40-60.
Lipoma shoulder lumps may form:
No-one knows why lipomas form but there is a genetic link so if someone in your family has had a lipoma soft tissue lump on their arm, you are at increased risk of developing them.
A lump on the shoulder caused by a lipoma is usually:
Most lipoma lumps on the shoulder are completely harmless and don’t require any treatment, but if they are causing problems, they can be removed surgically.
A muscle knot is a common cause of a lump on the back of the shoulder, around the shoulder blade, or in the neck. Also known as myofascial trigger points, knots are small, hard lumps caused by tension, spasming or tearing in the muscle fibres.
The trapezius muscle on the back of the shoulder, neck and upper back is a really common place to get muscle knots and these small, firm lumps are often painful to touch. The best way to treat muscle knots are a combination of stretches, massage, heat and posture re-education.
Find Out More: Trapezius Pain & Trigger Points
Another common cause of a painless lump on the shoulder are cysts, small sacs or lumps that may be filled with a substance such as fluid, pus or air and look similar to a blister. Cysts are very common and in most cases are completely harmless.
There are a number of different types of cyst but the ones that most often cause a lump on the shoulder are:
A lump on the shoulder from a cyst is usually:
Another possible cause of a lump on the shoulder is bursitis. Bursa are small, fluid-filled sacs that sit between soft tissues and bones to provide cushioning. Shoulder bursitis is where one of the bursa becomes inflamed, usually from repetitive friction or an injury which can lead to a lump on the shoulder that hurts when any pressure is placed on the affected bursa.
There are a number of different bursa around the shoulder, any of which can become inflamed, but the most common are:
Treatment for shoulder bursitis usually consists of a combination of rest, ice, physical therapy, injections, exercises and occasionally surgery. Find out more about Shoulder Bursitis Treatment.
A painful lump on the shoulder may be caused by an abscess, a collection of infected pus that forms deep below the skin, usually caused by a bacterial infection. The pus in an abscess is made up of white blood cells, dead tissue and bacteria.
A shoulder lump caused by an abscess usually presents as:
A small abscess lump on the shoulder (less than 0.5cm) should settle by itself – it can help to apply a warm compress for 30 minutes 3-4x daily, but larger abscess often need to be drained by your doctor to remove the infected fluid
Shoulder acne can also cause lumps on the shoulders and arms. Shoulder acne ranges from a few small white or black heads, to a large covering of pus filled spots.
Acne lumps under the skin on the shoulders and arms may be caused a range of things including excess oils that block glands, allergic reactions, blocked hair follicles and excess keratin. One of the most common types of acne to causes small lumps on the upper arm is keratosis pilaris.
Find Out More: Shoulder Acne Causes & Treatment
Many people worry when they find a lump on their shoulder that it may be cancer. In most cases, shoulder lumps are completely benign i.e. non-cancerous, but any new lumps should always be taken seriously.
There are a few different types of cancer that can cause a lump on the shoulder or upper arm, the most common being:
A soft, mobile shoulder lump is unlikely to be cancerous. A cancerous lump on shoulder often grows quite rapidly, changes shape or colour, and is hard and non-mobile. If you have a lump on your shoulder like that or you are experiencing unexplained weight loss, fatigue, are feeling unwell or find that your shoulder pain is mainly at night, see your doctor as soon as possible.
Another possible cause of shoulder lumps is arthritis. The term arthritis simply means joint inflammation and refers to a number of different conditions. The most common types of arthritis to cause shoulder lumps are:
In most cases a lump on the shoulder is nothing serious and will usually settle down on its own in a couple of weeks, but if you have any of the following symptoms, you should seek medical attention as soon as possible:
Depending on the size, location and history of your shoulder lump, your doctor may send you for a biopsy, ultrasound, MRI or CT scan to make an accurate diagnosis
There are many different treatments for lumps on the shoulder depending on the underlying cause, which may involve:
There are lots of different things that can cause lumps on shoulders but by thinking about your specific symptoms you can work out what is wrong:
Hopefully you now have a much better idea of what is causing the lump on your shoulder, but if you want more help working out what is wrong, or have other symptoms in your shoulder or upper arm, check out the shoulder pain diagnosis guide.
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Page Last Updated: 21/05/2022
Next Review Due: 21/05/2024