Lump or Mass
A lump is any bump, swelling, nodule, or mass you can see or feel that was not there before. The overwhelming majority turn out to be benign - fatty lipomas, cysts, reactive lymph nodes, and swellings from injury or inflammation account for almost all of them. What a lump feels like, how fast it appeared, and where on the body it sits do most of the diagnostic work. This guide explains how to read those clues, then points you to the detailed guide for your exact location.
Last updated August 27, 2026
⚠️ Get a Lump Checked Promptly If:
- It is growing noticeably over weeks
- It is larger than about 5 cm (2 inches)
- It feels hard and does not move when pressed
- It is deep to the muscle rather than just under the skin
- It hurts at night or wakes you from sleep
- The skin over it is red, hot, ulcerated, or breaking down
- You also have fever, night sweats, or unexplained weight loss
- It is in the breast or testicle
Find the Guide for Your Location
Lumps behave differently depending on what tissue lies beneath them, so the most useful next step is usually the guide for the exact body part.
Arm Lump or Mass
Upper arm and forearm lumps, including lipomas and cysts.
Leg Lump or Mass
Thigh, calf, and shin lumps, including Baker's cysts.
Shoulder Lump or Mass
Lipomas, sebaceous cysts, and bursitis swelling.
Elbow Lump or Mass
Olecranon bursitis, gouty tophi, and rheumatoid nodules.
Wrist Lump or Mass
Ganglion cysts and tendon sheath swellings.
Hand or Finger Lump
Joint nodules, cysts, and knuckle swellings.
Knee Lump or Mass
Baker's cysts, bursitis, and bony growths.
Foot or Toe Lump
Ganglion cysts, bunions, and gout tophi.
Neck Mass
Lymph nodes, thyroid swellings, and cysts.
Back Lump or Mass
Lipomas and cysts along the back and shoulder blade.
Groin Mass
Hernias, lymph nodes, and cysts in the groin.
Breast Lump
Always worth prompt assessment.
Mass in Scrotum
Testicular lumps, cysts, and varicoceles.
Lump in Throat
Globus sensation and genuine throat swellings.
Mass on Eyelid
Chalazion, styes, and eyelid cysts.
Lump Around the Anus
Haemorrhoids, skin tags, and abscesses.
How to Describe a Lump: The Five Features That Matter
When a doctor examines a lump, they are working through the same short checklist every time. Running through it yourself will tell you a great deal about how urgently it needs attention, and it makes the appointment far more productive.
1. Size
Measure it against something familiar - a pea, a grape, a golf ball. Anything over about 5 cm across is considered large and is usually imaged, regardless of how it feels. More important than the absolute size is whether it has changed: a lump that has been the same for five years behaves very differently from one that has doubled in a month.
2. Consistency
Soft and squashy suggests fat or fluid - typically a lipoma, cyst, or bursa. Rubbery and firm suggests a lymph node or a fibrous nodule. Rock-hard suggests bone, calcification, or dense scar tissue. Fluctuant, meaning it feels like a water balloon and springs back, points strongly to fluid and often to an abscess or cyst.
3. Mobility
Push the lump gently from side to side. If it slides freely under the skin, it is mobile, and that is generally reassuring. If it stays anchored no matter which way you press, it is fixed - tethered to muscle, tendon, or bone - and that is a feature doctors take seriously.
4. Depth
Lumps you can pinch up with the skin sit superficially and are usually skin or fat. Lumps that stay put when you lift the skin sit deeper. Depth to the muscle layer is one of the strongest predictors that a lump warrants imaging.
5. Pain and Skin Changes
Painful, red, hot lumps are usually inflammatory or infected, and often appear over hours to days. Painless lumps that grow slowly are more often benign growths - but painless does not mean harmless, since many concerning masses cause no pain at all until late. Skin that is ulcerating, dimpling, or discoloured over a lump always deserves attention.
The Most Common Causes of Lumps
Fat and Skin
- Lipoma (soft fatty lump)
- Sebaceous or epidermoid cyst
- Skin tag
- Dermatofibroma
- Wart or verruca
- Keloid scar
Lymph Nodes
- Reactive node from infection
- Node after vaccination
- Glandular fever
- Persistent enlarged node
- Node in neck, armpit, or groin
- Multiple enlarged nodes
Joints and Tendons
- Ganglion cyst
- Bursitis
- Baker's cyst
- Rheumatoid nodule
- Gouty tophus
- Bone spur (osteophyte)
Injury and Infection
- Haematoma (blood collection)
- Abscess
- Cellulitis with swelling
- Insect bite reaction
- Foreign body reaction
- Healing fracture callus
How Lumps Are Investigated
Most lumps need nothing more than an examination. When testing is warranted, it follows a predictable sequence.
- Ultrasound: The usual first test. It distinguishes solid from fluid, is quick, and involves no radiation.
- X-ray: Used when the lump feels bony or sits over a joint, to look for spurs, calcification, or bone changes.
- MRI: Reserved for lumps that are deep, large, or unclear on ultrasound. It shows soft tissue in detail.
- Blood tests: Inflammatory markers, urate levels, and infection screens when the picture suggests gout, infection, or a systemic cause.
- Aspiration: Drawing off fluid both relieves a swollen cyst or bursa and allows the fluid to be analysed.
- Biopsy: Taking a tissue sample, used when imaging cannot settle the diagnosis or concerning features are present.
Frequently Asked Questions
What does it mean when a lump moves under the skin?
A lump that slides freely when you push it is described as mobile, and mobility is generally reassuring. Lipomas (soft fatty lumps), sebaceous cysts, and reactive lymph nodes all move under the fingers because they are not attached to deeper structures. A lump that stays fixed in place when you press it may be anchored to muscle, tendon, or bone, and that is one of the features doctors use to decide whether imaging is needed.
Are hard lumps more serious than soft lumps?
Consistency is a clue rather than a verdict. Soft, squashy lumps are usually fat, fluid, or a cyst, and are very often harmless. Hard lumps more often involve bone, calcified tissue, or dense fibrous tissue, so they are looked at more carefully - but many hard lumps, such as a bone spur or a gouty tophus, are still benign. What matters more than hardness alone is the combination of hard, fixed, growing, and larger than about 5 cm.
How long should I wait before getting a lump checked?
A small, soft, painless lump that appeared after a knock or alongside an infection can reasonably be watched for two to four weeks, since many settle on their own. Book an appointment sooner if the lump is growing, is bigger than a golf ball, feels hard or fixed, is painful at night, or comes with fever, weight loss, or night sweats. Any lump in the breast or testicle should be checked promptly rather than watched.
What kind of doctor should I see about a lump?
Start with your primary care doctor or GP, who can examine the lump and arrange an ultrasound - the usual first test for a soft-tissue lump. From there you may be referred on: to dermatology for skin lumps, orthopaedics or a sarcoma service for lumps deep to the muscle, general surgery for lumps in the abdominal wall or groin, or a breast clinic for breast lumps. Going straight to a specialist is rarely necessary.