Is Arm or Leg Swelling a Sign of Cancer?

Start with the question a clinician will ask first. Is it one arm or leg, or both?

Both limbs swelling together usually points to something whole-body. Think heart, kidneys, liver, or a medicine that holds fluid.

One limb swelling on its own points to something local. A clot in a vein. An infection in the skin. A blockage in lymph drainage. Those need different tests and different speeds.

Say the side out loud when you call. It genuinely changes what happens next.

The NHS lists these symptoms of deep vein thrombosis:

• throbbing pain in one leg, usually the calf or thigh.
• swelling in one leg.
• skin around the painful area that is red, blue or darkened.
• swollen veins.

The same can happen in an arm. The NHS advice is to ask for an urgent appointment or call 111 in the UK if you think you have a DVT. In the US, call your clinician the same day or use urgent care.

Call 911 or go to an emergency department if swelling comes with breathlessness or chest pain. A clot that moves to the lungs is a pulmonary embolism, and that is time-critical.

Also treat it as an emergency if the limb turns suddenly cold, pale or blue and severely painful.

Cellulitis is a skin infection that can look a lot like a clot. The NHS describes skin that is painful, hot and swollen, often with flu-like symptoms, and advises urgent treatment so it does not spread.

Cellulitis becomes an emergency with a very high temperature, shivering, a fast heartbeat, confusion, or cold clammy skin.

Most swelling is not sinister:

• long flights, long drives, or standing all day.
• an injury, sprain or recent surgery.
• varicose veins and other vein problems.
• heart failure, kidney disease or liver disease.
• medicines, including some blood pressure tablets and steroids.
• pregnancy.

If you have had lymph nodes removed or radiation therapy, lymphedema is a real possibility. NCI describes a heavy, full or tight feeling in the area, swelling that may leave a dent when pressed, and numbness or tingling.

NCI's advice is direct: contact your doctor as soon as you notice heaviness, swelling or other symptoms, because lymphedema is easier to control when treatment starts early.

NCI also warns that cellulitis is a common complication of lymphedema, and says to call your doctor right away if you develop a fever or other signs of infection.

A growth can squeeze a vein and back fluid up behind it. In the chest this is called superior vena cava obstruction.

Macmillan lists breathlessness, facial swelling, a swollen neck, swollen arms and hands, headaches that worsen when you bend forward, visible veins on the chest, and vision changes. Macmillan says to contact your cancer team straight away, because it needs treating quickly.

For a swollen limb, ultrasound is usually the first real test. It shows whether blood is flowing normally through the vein. The NHS says someone with suspected DVT should be referred for a scan within 24 hours.

Beyond that, your clinician may check blood counts and kidney and liver function, look for signs of infection, arrange chest or abdominal imaging if a blockage higher up is suspected, or refer you to a lymphedema service.

Note the date the swelling started and how quickly it grew. Record whether it dents when pressed, whether the skin is warm, and whether it eases overnight.

Add recent flights, surgery, bed rest, hormone medicines, and any past lymph node surgery or radiation therapy. Lymphedema covers day-to-day management if that turns out to be the cause.

• NHS — DVT (deep vein thrombosis)
• NHS — Cellulitis
• National Cancer Institute — Lymphedema (PDQ)
• Macmillan Cancer Support — Superior vena cava obstruction