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Polyarteritis Nodosa

Polyarteritis nodosa

For medical students2 min readUpdated 2026-10-10

Polyarteritis nodosa (Polyarteritis nodosa, Kussmaul-Maier disease) is a systemic necrotizing vasculitis affecting medium- and small-sized muscular arteries. Without treatment, the disease carries a poor prognosis, with mortality rates reaching up to 90%.

EtiologyKey role of Hepatitis B and C viruses

MechanismANCA-associated damage (c-ANCA)

MorphologySegmental fibrinoid necrosis of vessels

Mortality75–90% mortality rate without treatment

Etiology and Pathogenesis

Classical polyarteritis nodosa is a distinct disease entity, though similar clinical features can be seen in secondary conditions such as rheumatoid arthritis, Sjögren syndrome, or hairy cell leukemia.

Key triggers and risk factors include:

Viral agents: Hepatitis B and C viruses play a major role, with cytomegalovirus, HIV, and parvovirus B19 being less common.
Infections and toxins: Streptococcal infections, medications (antibiotics, sulfonamides), toxins, and vaccinations.
Precipitating factors: Sun exposure can trigger disease manifestation.

The pathogenesis is driven by an immune-mediated response involving antineutrophil cytoplasmic antibodies. Polyarteritis nodosa is typically characterized by cytoplasmic c-ANCA directed against proteinase-3.

Morphological Changes and Stages

The pathological process affects small- and medium-sized muscular arteries, predominantly at bifurcations and branching sites due to immune complex deposition. A hallmark morphological feature is segmental fibrinoid necrosis.

The disease progresses through several sequential stages:

Acute stage: Vessel walls are infiltrated by neutrophils, eosinophils, and macrophages. Characteristic beaded nodular thickenings form, and areas of necrosis lead to ruptures and microaneurysms up to 1 cm in size. Vessel lumens are typically occluded by thrombi.
Chronic stage: The cellular infiltrate is replaced by mononuclear cells.
Healing/Sclerosis stage: Vessel lumens become completely obliterated, and their walls undergo cuff-like thickening.

A specific feature of this pathology is evolutionary polymorphism — the simultaneous presence of different stages of inflammation within the same blood vessel.

Clinical Forms and Complications

Modern classification distinguishes two primary forms:

Classical polyarteritis nodosa: Affects medium- and small-sized arteries, spares large arteries, veins, and venules, and does not cause glomerulonephritis.
Microscopic polyangiitis: Characterized by involvement of arterioles, capillaries, and venules, leading to pneumonitis and glomerulonephritis without immune complex deposition (typically associated with perinuclear p-ANCA).

Severe complications determine the prognosis:

Profuse hemorrhages due to the rupture of vascular aneurysms.
Peritonitis resulting from intestinal perforation secondary to ulcerating and necrotizing lesions.
Renal failure, which is the most frequent cause of patient mortality.

Mnemonic

Polyarteritis nodosa = N (nodules/aneurysms at bifurcations), P (polymorphism of stages in a single vessel), H (Hepatitis B and C as major triggers).

Frequently asked questions

Which target organs are most frequently involved in polyarteritis nodosa?

In polyarteritis nodosa, the kidneys, heart, liver, gastrointestinal tract, skeletal muscles, peripheral nervous system, and skin are most frequently involved.

Frequency of organ involvement by site:

Kidneys — renal arteries (most common).
Heart — coronary arteries.
Liver — hepatic arteries.
Gastrointestinal tract — mesenteric arteries.

Notably, pulmonary circulation vessels and glomerular capillaries are never involved in this disease.

What macroscopic and microscopic changes develop in the kidneys in classical polyarteritis nodosa?

Classical polyarteritis nodosa causes focal necrotizing inflammation of medium- and small-sized renal arteries, leading to infarctions.

Microscopic findings — segmental fibrinoid necrosis of the vessel wall, thrombosis, and microaneurysm formation. Glomerular capillary involvement and glomerulonephritis are absent.
Macroscopic findings — tissue infarction resulting from vascular thrombosis.
Renal involvement frequently leads to arterial hypertension and represents the leading cause of death.

Which vessels are affected in classical polyarteritis nodosa?

Medium- and small-sized muscular arteries are affected. Large arteries, veins, venules, and arterioles are spared in the classical form.

What is evolutionary polymorphism?

A specific feature of morphogenesis where different stages of vascular remodeling—ranging from acute inflammation with necrosis to fibrous scarring—are simultaneously observed within a single blood vessel.

Which antibodies are characteristic of polyarteritis nodosa?

Cytoplasmic antineutrophil cytoplasmic antibodies (c-ANCA) directed against proteinase-3 are typically characteristic.

What is the leading cause of death in this disease?

Progressive renal failure is the most frequent cause of death among patients.

Go deeper

Microscopic polyangiitis: morphological and mechanistic differences
The role of Hepatitis B virus in inducing systemic vasculitides
Differential diagnosis of c-ANCA and p-ANCA associated vasculitides
Pathomorphology of secondary vasculitides in rheumatic diseases
Dynamics of vascular remodeling during vasculitis healing into sclerosis