STEPTRACKERCARDIOVASCULAR | PATHOLOGY + IMMUNOLOGY | HIGH-YIELD REVIEW

Medium-Vessel Vasculitis

Polyarteritis nodosa, Kawasaki disease and Buerger disease — three very different patients, one vessel size.

FOCUS ON
PAN: HBV, kidneys and gut, mononeuritis multiplex, microaneurysms, ANCA-negative, spares the lungs. Kawasaki: child under 5 with 5 days of fever plus mucocutaneous signs; the danger is coronary aneurysm; treat with IVIG + aspirin. Buerger: young male smoker; stopping smoking is the treatment.
FEATURE
POLYARTERITIS NODOSA
KAWASAKI DISEASE
BUERGER DISEASE
Who
Middle-aged adults; ~30% HBV-associated
Children < 5, especially of Asian ancestry
Young male heavy smokers
Vessels
Medium arteries of kidney, gut, skin, nerves, heart — not lungs
Coronary and other medium arteries
Small and medium arteries and veins of hands and feet
Pathology
Transmural fibrinoid necrosis; acute and healed lesions side by side; immune complexes; ANCA ⁻
Acute necrotizing vasculitis → coronary aneurysms
Segmental thrombosing vasculitis that spreads to adjacent veins and nerves
Clinical
Hypertension (renal → renin), abdominal pain, melena, mononeuritis multiplex, skin nodules/ulcers, livedo reticularis, testicular pain
Fever ≥ 5 days + bilateral non-exudative conjunctivitis, polymorphous rash, cervical node, red cracked lips/strawberry tongue, swollen hands/feet → later desquamation
Claudication, Raynaud, superficial migratory thrombophlebitis, painful digital ulcers, gangrene, autoamputation
Diagnosis
Angiography: "string of pearls" microaneurysms; tissue biopsy
Clinical criteria; echocardiography for coronaries; ↑ ESR/CRP, later thrombocytosis
Angiography: corkscrew collaterals; exclude other causes
Complications
Renal failure, bowel infarction, MI
Coronary aneurysm → thrombosis, MI in childhood
Amputation
Treatment
Steroids + cyclophosphamide; antivirals for HBV-PAN
IVIG + aspirin (aspirin is the Reye exception)
Smoking cessation — the only effective treatment

Mechanism — immune complexes in medium arteries (PAN)

Antigene.g., HBsAg
→
Immune complexesDeposit in wall
→
Complement + neutrophilsFibrinoid necrosis
→
Healing fibrosisAneurysm or stenosis
→
Organ infarctsKidney, gut, nerve

Different segments at different stages give the classic "acute and healed lesions together" picture.

Medium- vs small-vessel clues

CLUE
MEDIUM VESSEL
SMALL VESSEL
Skin
Nodules, ulcers, livedo
Palpable purpura
Kidney
Renal infarcts, renovascular HTN
Glomerulonephritis
Lung
Spared (PAN)
Alveolar hemorrhage, nodules
Nerve
Mononeuritis multiplex
Possible (EGPA)
Imaging
Microaneurysms
Usually normal angiogram

How it's tested

COMMON CONFUSIONPAN causes kidney infarcts and hypertension, not glomerulonephritis. Glomerulonephritis with RBC casts points to a small-vessel vasculitis.
THE TRAPA child with Kawasaki disease gets aspirin despite the Reye syndrome warning. IVIG plus aspirin is the correct answer.
YOUR APPROACHAge and habits pick the disease: child → Kawasaki; young smoker → Buerger; adult with HBV, gut and nerve involvement → PAN.

If you see… think…

HBV carrier with hypertension, abdominal pain, foot drop, ANCA ⁻ → PAN
Renal and mesenteric "string of pearls" on angiography → PAN
Vasculitis that spares the lungs → PAN
3-year-old, fever 6 days, red eyes, strawberry tongue, swollen hands → Kawasaki — IVIG + aspirin
Child with an MI weeks after a febrile rash illness → coronary aneurysm (Kawasaki)
Fingertip peeling 2–3 weeks after a fever → Kawasaki (subacute phase)
Young male smoker, painful finger ulcers, migratory phlebitis → Buerger disease
Mononeuritis multiplex + livedo + testicular pain → PAN
Corkscrew collaterals on hand angiography → Buerger disease