Discovering a lump on your shoulder can be unsettling, even though the great majority turn out to be nothing serious. Understanding the possible causes, and knowing when to get it checked, makes it far easier to know what to do next.
This guide walks through the most common causes of shoulder lumps, the symptoms worth paying attention to, and how a same-day ultrasound scan gives you a clear answer.
01Common causes of a shoulder lump
A lump on your shoulder can come from many different sources, from a simple cyst to inflamed muscle. The most common include:
- Cyst, a closed sac of tissue containing fluid, air or pus. Epidermoid cysts and ganglion cysts are the most common types on the shoulder.
- Lipoma, a benign, soft and doughy lump of fatty tissue, usually painless unless it presses on a nerve or blood vessel.
- Muscle knot, a group of tense muscle fibres (a myofascial trigger point), often from overuse or inactivity.
- Abscess, a pus-filled lump caused by a bacterial infection, usually firm, warm and sometimes painful.
- Arthritis-related nodules, rheumatoid nodules from rheumatoid arthritis, or bony osteophytes from osteoarthritis.
- Injury, a fracture, a separated shoulder or a muscle contusion (a bruise that pools as a hematoma) can all leave a lump behind.
- Wart or large pimple, usually harmless, though warts are caused by HPV and can occasionally be confused with other skin changes.
Less commonly, a lump can be a soft tissue sarcoma or a skin cancer such as squamous cell carcinoma. These are rare, but it is exactly why any new or changing lump is worth having assessed properly.
02When to get a shoulder lump checked
Most shoulder lumps are harmless, but you should see a doctor if:
- It has persisted for more than two weeks
- It is growing in size
- It is painful or uncomfortable
- It does not move when you press it
- It appeared suddenly after an injury
If a lump follows a recent injury, or you notice signs such as fever, spreading redness or rapid growth, seek medical attention promptly rather than waiting.
03How a lump is diagnosed
Your doctor will usually start with a physical examination, feeling the lump and checking for associated signs such as redness or swelling. From there, imaging often gives the clearest answer.
An ultrasound scan is quick, painless and non-invasive, and is often the first and only test needed. It lets your specialist see the shoulder joint, assess your range of movement, examine the tendons, muscles and ligaments, and check for inflammation, fluid or other abnormalities, all in real time. Where a scan raises a question that needs a different kind of answer, an MRI, X-ray, CT scan or biopsy may be used alongside it.
The vast majority of shoulder lumps we see turn out to be simple things, a cyst, a lipoma, a knot in the muscle. An ultrasound tells you which, so you are not left wondering.
Dr Shayan Ahmed, consultant radiologist
04What to expect from your ultrasound
A shoulder ultrasound typically takes 15 to 30 minutes. Your specialist applies a clear, water-based gel and moves the probe over the lump, capturing live images that appear on a screen as they scan.
- Welcome and history5 min
- Physical examination10 min
- Ultrasound scan15 min
- Findings and your plan10 min
View as table
| Part of the visit | Typical time |
|---|---|
| Welcome and history | about 5 minutes |
| Physical examination | about 10 minutes |
| Ultrasound scan | about 15 minutes |
| Findings and your plan | about 10 minutes |
There is no aftercare required, and no anaesthesia involved. Your doctor will usually be able to explain the cause of the lump before you leave, and if follow-up treatment is needed, it is arranged from there.
05What happens next
Most people leave reassured, with a clear explanation of what the lump is and why it formed. If it does need further attention, your specialist tells you face to face and arranges the next step from there, whether that is a guided injection, a referral, or simply a plan to monitor it.