Vasculitis: What It Is, How It’s Diagnosed, and How It’s Treated

When your immune system turns on your own blood vessels, things go wrong fast. Vasculitis isn’t just a rash or a bad ache-it’s your body attacking the very pipes that carry blood to your organs. This isn’t rare, but it’s often missed because the symptoms look like the flu, arthritis, or even a sinus infection. By the time it’s caught, damage might already be done. The good news? If you know what to look for, and get the right care early, most people can live well with it.

What Exactly Is Vasculitis?

Vasculitis means inflammation of your blood vessels. That’s it. But that simple definition hides how dangerous it can be. When the walls of arteries, veins, or capillaries swell, they narrow. Blood flow slows. Sometimes, the vessel closes completely. Other times, it weakens and bulges into an aneurysm. Either way, the tissue downstream-your kidney, your nerve, your lung-starves for oxygen. That’s when organ damage starts.

It’s autoimmune, which means your immune system, confused or overactive, mistakes your vessel walls for invaders. It’s not caused by infection or injury. It’s not contagious. It’s not your fault. And it’s not one disease-it’s a group of more than 20 different conditions, each with its own pattern, severity, and treatment.

Doctors group them by the size of the vessels they hit:

• Large-vessel vasculitis: Affects the aorta and its biggest branches. Think giant cell arteritis (GCA), which hits arteries in the head, especially in people over 50. It can cause headaches, jaw pain when chewing, and even sudden vision loss.
• Medium-vessel vasculitis: Targets medium-sized arteries. Polyarteritis nodosa (PAN) and Kawasaki disease fall here. Kawasaki is mostly in kids under 5 and can cause coronary artery aneurysms if not treated fast.
• Small-vessel vasculitis: Hits the tiniest vessels-capillaries, venules. This includes the ANCA-associated types: granulomatosis with polyangiitis (GPA), microscopic polyangiitis (MPA), and eosinophilic granulomatosis with polyangiitis (EGPA). These often affect kidneys, lungs, and nerves.

What Are the Warning Signs?

There’s no single symptom. Vasculitis wears many masks. That’s why it takes, on average, 6 to 12 months to get diagnosed. People see multiple doctors before someone connects the dots.

Common signs include:

• Red or purple spots, bumps, or bruises on the skin-especially on the legs
• Joint pain or swelling that doesn’t go away
• Chronic fatigue, fever, or weight loss without reason
• Numbness, tingling, or weakness in hands or feet
• Shortness of breath or coughing up blood
• Stomach pain, diarrhea, or bloody stools
• Headaches, vision changes, or scalp tenderness (especially if you’re over 50)

If you’re over 50 and have new headaches or jaw pain when eating, don’t brush it off as aging. That’s classic giant cell arteritis. If a child has a fever for more than five days, red eyes, swollen hands, and a rash, get them checked for Kawasaki disease. These aren’t just random symptoms-they’re red flags for specific types of vasculitis.

How Is It Diagnosed?

There’s no single blood test for vasculitis. Diagnosis is a puzzle. Doctors piece it together using four things: your symptoms, lab tests, imaging, and biopsy.

Blood tests often show high inflammation:

• ESR (erythrocyte sedimentation rate) over 50 mm/hr
• CRP (C-reactive protein) above 5 mg/dL

But the real clue? Autoantibodies. The ANCA test finds anti-neutrophil cytoplasmic antibodies. c-ANCA (targeting proteinase-3) is 80-90% specific for GPA. p-ANCA (targeting MPO) often shows up in MPA. Finding these doesn’t confirm vasculitis alone-but it’s a huge clue.

Imaging helps too. CT scans, MRIs, or angiograms can show narrowed or blocked vessels. For large-vessel vasculitis like Takayasu’s or GCA, a PET scan can light up inflamed arteries.

But the gold standard? A biopsy. Taking a small piece of affected tissue-skin, kidney, lung, or temporal artery-lets pathologists see the inflammation up close. They look for white blood cells tearing through vessel walls, fibrinoid necrosis, or nuclear debris (leukocytoclasia). That’s the smoking gun.

How Is It Treated?

Treatment isn’t one-size-fits-all. It depends on the type, how bad it is, and which organs are at risk. The goal? Stop the immune attack, protect organs, and avoid long-term damage.

For most severe cases, treatment starts with high-dose steroids like prednisone-often 0.5 to 1 mg per kg of body weight daily. But steroids alone aren’t enough. They’re like putting a bandage on a gunshot wound. You need something stronger to calm the immune system.

That’s where immunosuppressants come in:

• Cyclophosphamide: Used for severe ANCA vasculitis. Powerful, but has long-term risks like bladder damage and infertility.
• Rituximab: Targets B-cells. Now often preferred over cyclophosphamide because it’s just as effective with fewer side effects.
• Methotrexate or azathioprine: Used for maintenance after remission. You’ll take these for 18 to 24 months to keep the disease quiet.

Newer drugs are changing the game. Avacopan, approved in 2021, blocks a protein called C5a that drives inflammation. In clinical trials, it let patients cut their steroid dose by 2,000 mg over a year-without losing control of the disease. That’s huge. Less steroid means fewer bone fractures, less weight gain, fewer infections.

For giant cell arteritis, tocilizumab (an IL-6 blocker) is now approved to help reduce steroid use. For EGPA, mepolizumab (which targets eosinophils) has shown promise in cutting relapses by half.

And then there’s Buerger’s disease-vasculitis tied to smoking. No drug works unless you quit tobacco completely. No exceptions. Even one cigarette a day can undo everything.

What’s the Long-Term Outlook?

The good news? Most people go into remission. Around 80-90% of those with ANCA-associated vasculitis do. The bad news? Half of them will relapse within five years. That’s why lifelong monitoring is key.

Your risk of serious complications depends on which organs are involved. The Five Factor Score helps predict survival:

• No major organ damage? 95% five-year survival.
• One major organ affected (kidney, heart, GI)? Drops to 75%.
• Two or more? Falls to 50%.

Kidneys are especially vulnerable. Vasculitis can damage them silently. That’s why doctors check urine for blood or protein-even if you feel fine. A simple dipstick test can catch early kidney injury before it’s too late.

For kids with Kawasaki disease, the biggest concern is coronary artery aneurysms. Up to 25% of untreated cases develop them. But with IVIG and aspirin within 10 days of fever, that risk drops below 5%.

What Should You Do If You Suspect Vasculitis?

If you’ve had unexplained symptoms for more than a few weeks-fatigue, rashes, joint pain, numbness, or breathing trouble-don’t wait. Go to your doctor. Ask: “Could this be vasculitis?”

If your primary care provider isn’t familiar, ask for a referral to a rheumatologist. These are the specialists who see vasculitis every day. They know which tests to order and when to act fast.

Keep a symptom journal. Note when things started, what makes them better or worse, and any new symptoms. Bring it with you. This isn’t just helpful-it’s critical. Many patients are dismissed because their symptoms seem “vague.” But when you can show a pattern, it changes everything.

And if you’re diagnosed? Stay on your meds. Don’t stop steroids just because you feel better. Relapse is common. And if you smoke-quit now. No half-measures. Your blood vessels are already under attack. Don’t give them another enemy.

What’s New in Research?

Scientists are looking for better ways to predict flares before they happen. Studies are testing biomarkers like BAFF (B-cell activating factor) and MCP-1 in urine to spot early signs of inflammation. The goal? To replace guesswork with precision.

Clinical trials are also testing drugs like abatacept for giant cell arteritis and newer B-cell therapies for relapsing cases. The future is moving toward personalized treatment-matching the right drug to the right patient based on their immune profile.

One thing’s clear: vasculitis is no longer a death sentence. With early diagnosis, proper treatment, and ongoing care, most people live full, active lives. It’s not easy. But it’s manageable. And the tools to fight it are better now than ever before.