Medium Vessel Vasculitis

Medium vessel vasculitis is the category of vasculitides that predominantly affects medium-sized arteries — the main visceral arteries and their branches. Its principal forms in the Chapel Hill nomenclature are polyarteritis nodosa, a necrotising arteritis classically sparing the lungs and not associated with ANCA, and Kawasaki disease, a self-limited febrile vasculitis of childhood with a predilection for the coronary arteries.

Definition

Medium vessel vasculitis is vasculitis predominantly affecting medium-sized arteries (the main visceral arteries and their branches), comprising principally polyarteritis nodosa and Kawasaki disease, per the 2012 Revised Chapel Hill Consensus Conference nomenclature.

Scope

The entry covers the definition of medium vessel vasculitis, its two main entities (polyarteritis nodosa and Kawasaki disease), their characteristic vessel involvement and complications such as aneurysm formation, and the position of these entities within the Chapel Hill nomenclature. It is a reference topic and does not provide diagnostic or treatment instructions.

Core questions

• Which medium-sized arterial beds are involved, and what aneurysmal or ischaemic complications result?
• How does polyarteritis nodosa differ from ANCA-associated small vessel vasculitis?
• What distinguishes Kawasaki disease as a childhood vasculitis with coronary predilection?
• How does association with hepatitis B inform some cases of polyarteritis nodosa?

Key concepts

• Necrotising arteritis
• Polyarteritis nodosa
• Kawasaki disease
• Coronary artery aneurysms
• Visceral artery microaneurysms
• Absence of ANCA association
• Hepatitis B-associated polyarteritis nodosa

Mechanisms

In medium vessel vasculitis, necrotising inflammation of medium-sized arteries can produce wall destruction with microaneurysm formation, thrombosis, and infarction of supplied organs. Polyarteritis nodosa is typically a non-granulomatous necrotising arteritis without glomerulonephritis or ANCA, and a subset is associated with hepatitis B virus infection. Kawasaki disease is an acute self-limited vasculitis of childhood whose major consequence is inflammation of the coronary arteries, which can lead to coronary artery aneurysms; it is frequently accompanied by a mucocutaneous lymph node syndrome.

Clinical relevance

Medium vessel vasculitis is the reference category for vasculitis of the main visceral arteries, and recognising its aneurysmal and ischaemic patterns informs how clinicians interpret angiographic and histologic findings reported in the literature. This entry characterises the disease category for educational reference and is not a basis for individual diagnosis or treatment.

Epidemiology

Polyarteritis nodosa is uncommon and has become rarer where hepatitis B vaccination and treatment have reduced virus-associated cases; it can occur across adulthood. Kawasaki disease is among the more common vasculitides of childhood, with the highest reported incidence in East Asian populations, particularly Japan, and predominantly affects children under five.

Evidence & guidelines

The 2012 Revised Chapel Hill Consensus Conference defines the category and distinguishes polyarteritis nodosa from ANCA-associated vasculitis. For Kawasaki disease, the American Heart Association scientific statement summarises diagnosis and long-term management, including coronary surveillance. These documents frame how the entities are recognised and classified.

History

Polyarteritis nodosa was described by Kussmaul and Maier in 1866 as periarteritis nodosa, long serving as a prototype of systemic necrotising vasculitis until later schemes separated ANCA-associated forms from it. Kawasaki disease was first reported by Tomisaku Kawasaki in 1967, and recognition of its coronary complications established it as a distinct medium-vessel entity in the Chapel Hill nomenclature.

Key figures

• Adolf Kussmaul
• Rudolf Maier
• Tomisaku Kawasaki
• J. Charles Jennette

Seminal works

• jennette-2012
• mccrindle-2017

Frequently asked questions

What are the main forms of medium vessel vasculitis?

Polyarteritis nodosa, a necrotising arteritis of medium-sized arteries that is not associated with ANCA, and Kawasaki disease, a childhood vasculitis with a predilection for the coronary arteries.

How does polyarteritis nodosa differ from ANCA-associated vasculitis?

Polyarteritis nodosa predominantly affects medium-sized arteries, is typically not associated with ANCA, and characteristically lacks glomerulonephritis, whereas ANCA-associated vasculitis chiefly affects small vessels and is often associated with ANCA and pauci-immune glomerulonephritis.