Vasculitis and Vasculitic Syndromes

Vasculitis denotes inflammation of blood vessel walls, a process that can damage vessels of any size and in any organ. The vasculitic syndromes are a heterogeneous family of diseases grouped chiefly by the calibre of the vessels predominantly affected and by associated immunologic features, and they range from localized cutaneous forms to life-threatening multisystem disease.

Definition

Vasculitis is inflammation of blood vessels leading to vessel-wall damage, which may cause stenosis, occlusion, aneurysm, or rupture and consequent ischaemia or haemorrhage in the tissues supplied; the vasculitic syndromes are the named clinical entities defined by the dominant vessel size and accompanying pathological and serological features.

Scope

This area orients the reader to the classification and shared concepts of the vasculitides as a reference subject within rheumatology. It introduces the size-based framework that organizes large-, medium-, and small-vessel disease and points to the individual syndromes covered as topics. It does not provide diagnostic protocols or treatment regimens.

Sub-topics

• Giant Cell Arteritis (Temporal Arteritis)

Key concepts

• Vessel-size-based classification (large, medium, small)
• Primary versus secondary vasculitis
• ANCA-associated versus immune-complex small-vessel vasculitis
• Chapel Hill Consensus Conference nomenclature
• Ischaemia from luminal narrowing versus aneurysm and rupture
• Single-organ versus systemic involvement

Mechanisms

The vasculitides share inflammation of the vessel wall but differ in the dominant mechanism. Some, such as giant cell arteritis, are driven by granulomatous, T-cell-mediated inflammation of large and medium arteries; others, such as the ANCA-associated vasculitides, involve neutrophil activation and pauci-immune injury of small vessels; and still others, such as cryoglobulinaemic vasculitis, are mediated by immune-complex deposition. The 2012 Revised Chapel Hill Consensus Conference grouped the syndromes primarily by the size of vessel predominantly affected while recognizing these distinct immunopathologic pathways.

Clinical relevance

Recognizing that diverse syndromes share vessel-wall inflammation helps organize a large and otherwise confusing group of diseases, and the size-based framework underlies how these conditions are described and studied. This entry is a conceptual map of the field for reference and education and is not a basis for individual diagnosis or treatment.

Epidemiology

As a group the vasculitides are uncommon, and individual syndromes vary widely in frequency, age distribution, and geography; giant cell arteritis predominates in older adults of northern European ancestry, whereas some small-vessel forms occur across the lifespan. Population-level detail is given in the individual topic entries.

Evidence & guidelines

The 2012 Revised International Chapel Hill Consensus Conference nomenclature is the reference framework for naming and grouping the vasculitides, and professional bodies such as EULAR and the American College of Rheumatology publish classification criteria and management recommendations for the major syndromes. These statements are described here for orientation and are not reproduced as actionable protocols.

History

Individual vasculitic diseases were described across the nineteenth and twentieth centuries under varied eponyms, and successive efforts at unified classification culminated in the Chapel Hill Consensus Conferences of 1994 and 2012, which provided the size-based nomenclature now widely used.

Key figures

• J. Charles Jennette
• Ronald J. Falk
• Cornelia Weyand
• Jörg Goronzy

Seminal works

• jennette-2013-chcc
• hellmich-2020-lvv

Frequently asked questions

How are the vasculitides classified?

The most widely used framework, from the 2012 Revised Chapel Hill Consensus Conference, groups them primarily by the size of the vessels predominantly affected (large, medium, and small), with further distinctions based on immunologic features such as ANCA association or immune-complex deposition.

What is the difference between primary and secondary vasculitis?

Primary vasculitis arises without an identified underlying cause, whereas secondary vasculitis occurs in the context of another condition such as an infection, a connective tissue disease, a drug exposure, or a malignancy.