Page 364 - The Vasculitides, Volume 1: General Considerations and Systemic Vasculitis

338 Sarah Conway and David S. Younger

nervous system vasculitis (PCNSV) in children and adults. Galetta [1] has reviewed the
neuro-ophthalmologic aspects of vasculitides.

Classification of Vasculitis

Two Chapel Hill Consensus Conferences (CHCC), one in 1994, and the other revised in
2012 [2, 3], provided consensus on nosology and definitions for the commonest forms of
vasculitis in adults based upon the caliber of vessels involved. The Pediatric Rheumatology
European Society (PRES) and the European League against Rheumatism (EULAR) proposed
specific classification criteria for the commonest childhood vasculitis syndrome [4] based
upon vessel size similar to the CHCC nomenclature [3]. The EULAR, PRES, and the
Pediatric Rheumatology International Trials Organization (PRINTO) defined the clinical,
laboratory and radiographic characteristics for several childhood systemic vasculitides in a
validated classification of pediatric vasculitis [5]. There is a continuum of vasculitic disorders
with some occurring exclusively in childhood or in older adults, and others across the age
spectrum although with differing epidemiology, clinical and laboratory manifestations, and
response to treatment. Large vessel vasculitis (LVV) includes giant cell arteritis (GCA) and
Takayasu arteritis (TAK) affects the aorta, its major branches and analogous veins. Medium
vessel vasculitis (MVV) includes polyarteritis nodosa (PAN) and Kawasaki disease (KD)
with typical involvement of main visceral arteries and veins and initial branches. Small vessel
vasculitis (SVV) comprises disorders with vasculitis of intraparenchymal arteries, arterioles,
capillaries, veins and venules, and disease pathogenesis related to anti-neutrophil cytoplasmic
antibody (ANCA) production, or the formation of immune complexes (IC). The category of
ANCA-associated vasculitis (AAV) includes granulomatosis with polyangiitis (GPA)
(Wegener granulomatosis type), eosinophilic granulomatosis with polyangiitis (EGPA)
(Churg-Strauss syndrome type), and microscopic polyangiitis (MPA) (microscopic
polyarteritis), while vasculitic disorders associated with IC include hypocomplementemia
urticarial vasculitis (C1q), cryglobulinemic vasculitis (CV), and IgA vasculitis (IgAV)
(formerly Henoch-Schönlein purpura [HSP]). Vasculitis without a predominant vessel size
and caliber, respectively from small to large, involving arteries, veins and capillaries,
comprises the category of variable vessel vasculitis (VVV), characteristic of Behçet disease
(BD) and Cogan syndrome (CS). The category of single-organ vasculitis (SOV), that involves
arteries or veins of any size in a single organ without features to indicate that it is a limited
expression of a systemic vasculitis, is typified by central nervous system (CNS) vasculitis.

Large Vessel Vasculitis

Giant Cell Arteritis

This granulomatous LVV involves cranial branches of the arteries arising from the arch
of the aorta. It occurs exclusively in individuals older than age 50 years, with an annual
incidence of 15-25 persons per 100,000, with higher rates in Caucasian individuals compared
to African Americans, and among women compared to men in a ratio of 2 to 3:1 [6-9].

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