Vasculitis Buzzwords for Board Exams: Vessel Size, Organs, and Antibodies

Vasculitis questions on COMLEX and USMLE get easy once you sort each disease by vessel size and then attach one patient, one organ pattern, and one lab clue to it. Large-vessel disease is giant cell arteritis (over 50, headache, jaw claudication) and Takayasu arteritis (young Asian woman, weak arm pulses). Medium-vessel disease is polyarteritis nodosa (hepatitis B, spares the lungs), Kawasaki disease (child under 5, coronary aneurysms), and Buerger disease (young smoker, digital gangrene). Small-vessel disease is where the antibodies live: c-ANCA for granulomatosis with polyangiitis, p-ANCA for microscopic polyangiitis and EGPA, IgA deposits for IgA vasculitis, and hepatitis C with low C4 for cryoglobulinemia.

That's the whole map. The rest of this guide fills in the buzzwords that question writers plant for each disease and the traps that make two of them look alike.

Why does vessel size matter so much on board questions?

Vessel size predicts what the patient looks like. Large vessels are the aorta and its major branches, so blocking them causes limb claudication, pulse differences, and vision loss from cranial branches. Medium vessels are the main visceral arteries, so inflaming them causes organ infarcts, aneurysms, and nerve damage. Small vessels are arterioles, capillaries, and venules, so inflaming them causes palpable purpura, glomerulonephritis, and lung hemorrhage.

You can use that logic in reverse on a stem. Palpable purpura on the legs is a small-vessel finding almost every time. A wrist drop or foot drop from mononeuritis multiplex points to the vasa nervorum, which means medium-vessel disease (or EGPA, which reaches into medium vessels too). Unequal blood pressures between the arms point to the aortic arch. Once you've named the vessel size, the differential drops from about a dozen diseases to three or four.

The classification here follows the 2012 Chapel Hill consensus nomenclature, which is what First Aid and the major question banks use. Behçet disease sits in its own "variable vessel" group, and I've covered it separately below.

The vasculitis cheat sheet

Read across any row and you'll see one patient profile and one clue that nobody else on the table shares. The stem usually gives you that clue in the first two or three lines.

Large-vessel vasculitis: giant cell arteritis and Takayasu arteritis

Both large-vessel diseases are granulomatous inflammation of the aorta and its main branches, and both raise the ESR. Age is what splits them. The age line is 50, and a stem will almost always give you a patient well on one side of it.

Giant cell arteritis: the older patient with a headache

Giant cell arteritis (temporal arteritis) is the most common systemic vasculitis in adults over 50. The stem gives a new headache over the temple, scalp tenderness when combing hair, and jaw pain that comes on with chewing (jaw claudication). Shoulder and hip girdle stiffness in the morning is polymyalgia rheumatica, which often travels with giant cell arteritis. The temporal artery may feel tender, thickened, or pulseless.

The feared complication is permanent vision loss from ischemia of the optic nerve. That's why the management answer is high-dose glucocorticoids right away, before the biopsy result comes back. Steroids don't erase the biopsy findings in the first days, so waiting for tissue only risks the other eye.

Temporal artery biopsy shows granulomatous inflammation with multinucleated giant cells. The inflammation is segmental, with "skip lesions," so a negative short biopsy doesn't rule the disease out. Over the long term, these patients carry a higher risk of thoracic aortic aneurysm, which is how giant cell arteritis sometimes shows up in an aortic dissection question.

Takayasu arteritis: the young woman without a pulse

Takayasu arteritis is called "pulseless disease." The classic patient is a woman under 40, often of Asian descent, with weak or absent radial pulses, arm pain with use, a blood pressure difference between the two arms, and a bruit over the subclavian artery. Early on she may only have fever, night sweats, weight loss, and joint pain, which is why the stem often adds an elevated ESR.

Imaging shows thickening and narrowing of the aortic arch and its proximal branches. Involvement of the aortic root can cause aortic regurgitation. Treatment starts with glucocorticoids.

Medium-vessel vasculitis: polyarteritis nodosa, Kawasaki, and Buerger

Medium-vessel disease attacks the main arteries feeding the organs. Expect infarcts, aneurysms, and nerve damage rather than purpura and glomerulonephritis.

Polyarteritis nodosa: hepatitis B and a body full of infarcts

Polyarteritis nodosa (PAN) is a necrotizing vasculitis of medium arteries, classically tied to hepatitis B infection. A middle-aged adult comes in with fever, weight loss, and a scattered set of organ problems. Renal artery involvement causes new hypertension and renal infarcts. Mesenteric artery involvement causes abdominal pain after meals and can cause bowel infarction. Nerve involvement causes mononeuritis multiplex, such as a sudden foot drop. The skin may show livedo reticularis, tender nodules, or ulcers, and testicular pain is a classic extra.

Two negatives carry this disease on exams. PAN spares the lungs, and it's ANCA negative. If a stem gives you lung involvement or a positive ANCA, you're looking at a small-vessel disease instead.

Angiography shows multiple microaneurysms and narrowing along renal and mesenteric arteries, described as a "string of pearls" or "rosary" pattern. Histology shows transmural inflammation with fibrinoid necrosis, and lesions at different stages sit side by side in the same vessel. Treatment is glucocorticoids, with cyclophosphamide for severe disease. Hepatitis B associated cases also get antiviral therapy.

Kawasaki disease: the child with five days of fever

Kawasaki disease is the medium-vessel vasculitis of young children, usually under 5, with a higher incidence in children of Asian descent. The diagnosis is clinical: fever for at least 5 days plus at least 4 of 5 findings. Those findings are nonexudative conjunctivitis, red cracked lips or a strawberry tongue, a polymorphous rash, cervical lymphadenopathy (usually one node at least 1.5 cm), and red, swollen hands and feet that later peel. The common mnemonic is "CRASH and burn," with burn standing for the fever.

The question that matters is the heart. Kawasaki disease can cause coronary artery aneurysms, which can thrombose and cause a myocardial infarction in a toddler. Every patient gets an echocardiogram. Treatment is intravenous immunoglobulin (IVIG) plus aspirin. The 2017 American Heart Association statement reports that IVIG lowers the risk of coronary aneurysm from about 25% to about 4%. Aspirin in a child is a deliberate exception to the Reye syndrome rule, and boards like to test that.

The rash itself is covered with the other pediatric exanthems in the childhood rash buzzwords guide.

Buerger disease: the smoker losing fingertips

Buerger disease (thromboangiitis obliterans) is a segmental, thrombosing vasculitis of small and medium arteries and veins in the hands and feet. The patient is almost always a young man who smokes heavily. The stem gives painful fingertips or toes, foot claudication, Raynaud phenomenon, superficial thrombophlebitis that moves around, and eventually ulcers, gangrene, and autoamputation of digits.

There's no antibody to order. The only treatment that stops progression is complete smoking cessation, and that's the answer when the question asks for the most effective intervention.

Small-vessel vasculitis: where the antibodies live

Small-vessel disease hits arterioles, capillaries, and venules. The organ findings repeat across these diseases (purpura, nephritis, lung hemorrhage), so the antibody or deposit is usually what names the disease.

Granulomatosis with polyangiitis: the c-ANCA triad

Granulomatosis with polyangiitis (GPA, formerly Wegener granulomatosis) hits three areas. The upper airway gives chronic sinusitis, otitis media, nasal ulcers, and a saddle-nose deformity from cartilage destruction. Lower airway involvement brings hemoptysis and cavitating lung nodules. The kidneys develop a rapidly progressive, pauci-immune glomerulonephritis with crescents.

The antibody is c-ANCA directed against proteinase 3 (PR3). Biopsy shows necrotizing granulomatous inflammation. Treatment is glucocorticoids plus rituximab or cyclophosphamide.

Microscopic polyangiitis: GPA without the nose

Microscopic polyangiitis (MPA) also causes pulmonary hemorrhage and pauci-immune glomerulonephritis. What it lacks is granulomas and upper airway disease. No sinus findings, no saddle nose, no cavitating nodules. The antibody is p-ANCA directed against myeloperoxidase (MPO).

EGPA: the asthmatic with eosinophils and a foot drop

Eosinophilic granulomatosis with polyangiitis (EGPA, formerly Churg-Strauss syndrome) shows up in an adult with adult-onset or worsening asthma, chronic sinusitis, and marked peripheral eosinophilia. Mononeuritis multiplex is common, and cardiac involvement (myocarditis, cardiomyopathy) is the leading cause of death. IgE is often elevated, and p-ANCA (MPO) is positive in a subset of patients.

When a stem gives asthma plus eosinophils plus a neuropathy, think EGPA before you think about allergies.

IgA vasculitis: the child with purpura on the buttocks

IgA vasculitis (Henoch-Schönlein purpura) is the most common systemic vasculitis of childhood. The stem gives a child, often a week or two after an upper respiratory infection, with palpable purpura on the buttocks and the backs of the legs, joint pain, and colicky abdominal pain. IgA immune complexes deposit in small vessels of the skin, gut, and kidney.

Platelets and coagulation studies are normal, which is how you separate it from ITP. The GI complication boards love is ileoileal intussusception, covered in the pediatric intussusception guide. The kidney lesion looks the same as IgA nephropathy, with mesangial IgA deposits on biopsy, and kidney involvement drives long-term prognosis.

Cryoglobulinemic vasculitis: hepatitis C and a low C4

Mixed cryoglobulinemia is an immune complex vasculitis most often driven by hepatitis C. Immunoglobulins precipitate in the cold and deposit in small vessels. The classic triad is palpable purpura, joint pain, and weakness, and a peripheral neuropathy can join it. The kidney lesion is usually membranoproliferative glomerulonephritis. Complement is low, with C4 dropping more than C3. Treating the hepatitis C is central to management.

If you want the kidney side of these small-vessel diseases in more depth, the nephritic syndrome buzzwords guide walks through the biopsy and complement patterns.

Behçet disease: ulcers in two places plus the eye

Behçet disease can involve vessels of any size, which is why Chapel Hill lists it as variable-vessel vasculitis. The patient is usually a young adult from the old Silk Road belt (Turkey, the Middle East, East Asia). Look for recurrent painful oral aphthous ulcers, genital ulcers, and uveitis. Erythema nodosum and a positive pathergy test (a pustule at the site of a needle prick) round it out. The genetic association is HLA-B51. Behçet disease can also cause venous thrombosis.

What do c-ANCA and p-ANCA actually tell you?

c-ANCA (PR3) points to granulomatosis with polyangiitis. p-ANCA (MPO) points to microscopic polyangiitis or EGPA. A negative ANCA with a multi-organ vasculitis and hepatitis B points to polyarteritis nodosa. That three-way split answers most antibody questions in this topic.

A few extra associations show up often enough to memorize:

• Drug-induced p-ANCA. Hydralazine and propylthiouracil can induce MPO-ANCA vasculitis. Stopping the drug is part of the answer.
• Levamisole-adulterated cocaine. This can cause an ANCA-positive vasculitis with purpura classically on the ears.
• p-ANCA outside vasculitis. Ulcerative colitis and primary sclerosing cholangitis can also have a positive p-ANCA. A positive test in a patient with bloody diarrhea is not a vasculitis question.
• Anti-GBM antibodies. These are not ANCA. They point to Goodpasture syndrome, which shows linear IgG on kidney biopsy and has normal complement.

Which organ patterns point to which vasculitis?

Organ patterns are the second filter after vessel size. When a stem gives you two organs together, this list narrows it fast.

• Lungs and kidneys together (pulmonary-renal syndrome). GPA, MPA, EGPA, and anti-GBM disease. PAN is never on this list.
• Nerves (mononeuritis multiplex). PAN, EGPA, and sometimes MPA. Cryoglobulinemia causes a peripheral neuropathy as well.
• Gut. PAN causes mesenteric ischemia with pain after meals. IgA vasculitis causes colicky pain and intussusception in a child.
• Eyes. Giant cell arteritis causes sudden vision loss. Behçet disease causes uveitis. Kawasaki disease causes conjunctivitis without pus.
• Heart and aorta. Kawasaki disease causes coronary aneurysms. EGPA causes myocarditis. Takayasu arteritis can cause aortic regurgitation, and giant cell arteritis raises the risk of thoracic aortic aneurysm.
• Skin. Palpable purpura means small-vessel disease. Livedo reticularis and tender nodules suggest PAN. Digital gangrene in a smoker is Buerger disease.

How do I pick the right vasculitis when two look alike?

Run the stem through the same clues I look for in every question: age, acuity, unusual findings, matching timelines, labs and imaging, and the question part. Here's how they apply to vasculitis.

1. Age. Under 5 with fever is Kawasaki. A school-age child with purpura is IgA vasculitis. A woman under 40 with weak arm pulses is Takayasu. Over 50 with a headache is giant cell arteritis.
2. Acuity. New vision symptoms in suspected giant cell arteritis make steroids urgent. Kidney function dropping over days to weeks means a crescentic, pauci-immune glomerulonephritis, which points back to the ANCA diseases.
3. Unusual findings. Saddle nose, asthma, jaw claudication, genital ulcers, and peeling fingertips each map to one disease on the cheat sheet.
4. Matching timelines. Purpura a week or two after a URI fits IgA vasculitis. Fever that has lasted 5 days in a toddler fits Kawasaki.
5. Labs and imaging. Hepatitis B points to PAN, hepatitis C to cryoglobulinemia, PR3 to GPA, MPO to MPA or EGPA, and eosinophilia to EGPA. A "string of pearls" angiogram is PAN.
6. The question part. "Most likely diagnosis," "next best step," and "most likely complication" are three different questions. For Kawasaki, the complication is a coronary aneurysm. For giant cell arteritis, the next step is steroids before biopsy.

These pairings stick faster when you review missed questions by pattern instead of one at a time. The guide on how to review practice questions efficiently covers that habit. If you want vasculitis and the rest of cardiovascular pathology scheduled into the weeks you have left, the free Premeducated Study Plan Builder builds a day-by-day plan around your exam date.

Common traps on vasculitis questions

Trap 1: Waiting for the biopsy in giant cell arteritis. A patient over 50 with a temporal headache and visual symptoms needs high-dose steroids now. Biopsy comes after.

Trap 2: Giving PAN a lung finding. PAN spares the lungs and is ANCA negative. Hemoptysis or a positive ANCA moves you to the small-vessel diseases.

Trap 3: Calling IgA vasculitis ITP. Both cause purpura in a child after a viral illness. Palpable purpura on the buttocks and legs with normal platelets is IgA vasculitis, and a low platelet count with flat petechiae is ITP.

Trap 4: Mixing up GPA and MPA. Both cause lung hemorrhage and pauci-immune glomerulonephritis. Upper airway disease, granulomas, and c-ANCA belong to GPA. MPA has none of those and carries p-ANCA.

Trap 5: Holding aspirin in Kawasaki disease. Reye syndrome is the reason to avoid aspirin in most children. Kawasaki disease is the exception, and aspirin goes in with IVIG.

Frequently asked questions about vasculitis buzzwords

Which vasculitis is associated with hepatitis B and which with hepatitis C?

Hepatitis B is classically associated with polyarteritis nodosa, a medium-vessel vasculitis that causes renal infarcts, mesenteric ischemia, and mononeuritis multiplex while sparing the lungs. Hepatitis C is associated with mixed cryoglobulinemic vasculitis, a small-vessel disease that causes palpable purpura, joint pain, weakness, and membranoproliferative glomerulonephritis with a low C4. Both are immune complex diseases, so treating the underlying viral infection is part of management.

What is the difference between c-ANCA and p-ANCA?

c-ANCA produces a cytoplasmic staining pattern and targets proteinase 3 (PR3). It's the antibody of granulomatosis with polyangiitis. p-ANCA produces a perinuclear pattern and targets myeloperoxidase (MPO). It's seen in microscopic polyangiitis, EGPA, and drug-induced vasculitis from hydralazine or propylthiouracil. p-ANCA can also be positive in ulcerative colitis and primary sclerosing cholangitis, so it isn't specific for vasculitis on its own.

How do I tell giant cell arteritis from Takayasu arteritis?

Age is the fastest split. Giant cell arteritis affects adults over 50 and presents with a temporal headache, scalp tenderness, jaw claudication, vision changes, and often polymyalgia rheumatica. Takayasu arteritis affects women under 40, classically of Asian descent, and presents with weak arm pulses, arm claudication, and a blood pressure difference between the arms. Both are granulomatous large-vessel vasculitides with a high ESR, and both are treated with glucocorticoids.

Why is aspirin given in Kawasaki disease if it causes Reye syndrome?

Kawasaki disease can cause coronary artery aneurysms, which can clot and lead to myocardial infarction in a young child. Aspirin is given with IVIG for its anti-inflammatory and antiplatelet effects, and that benefit outweighs the Reye syndrome risk in this setting. The 2017 American Heart Association statement reports that IVIG lowers the rate of coronary aneurysm from about 25% to about 4%. Every child with Kawasaki disease also gets an echocardiogram.

Which vasculitides cause both lung and kidney disease?

Granulomatosis with polyangiitis, microscopic polyangiitis, and EGPA can all cause pulmonary hemorrhage with a pauci-immune glomerulonephritis. Anti-GBM disease (Goodpasture syndrome) causes the same pairing through antibodies against type IV collagen, with linear IgG on biopsy. Polyarteritis nodosa affects the kidney through renal artery infarcts but spares the lungs. Upper airway findings and the ANCA type separate the small-vessel diseases from each other.

Are vasculitis buzzwords tested differently on COMLEX and USMLE?

Both exams test the same diseases and the same buzzwords. The question types repeat: name the vasculitis from the patient profile, pick the antibody or biopsy finding, name the complication, or choose the next step in management. Sorting by vessel size first, then by patient, organ, and antibody, covers those question types on either exam.

Related guides

• Nephritic syndrome board buzzwords: a disease-by-disease guide
• Childhood rash buzzwords for COMLEX and USMLE
• Intussusception vs volvulus vs pyloric stenosis on pediatric board questions
• Aortic dissection buzzwords on COMLEX and USMLE
• How to review practice questions efficiently
• Doctor Lucas DO on YouTube: question breakdowns and high-yield clinical comparison videos