Page 399 - The Vasculitides, Volume 1: General Considerations and Systemic Vasculitis

Dermatologic Aspects of Systemic Vasculitis 373

Rheumatism (EULAR) and the Pediatric Rheumatology International Trials Organization
(PRINTO) proposed nosology and classification for several of the primary pediatric
vasculitides based upon vessel size [6,7] similar to the CHCC nomenclature [5].

Epidemiology

The incidence of cutaneous vasculitis ranges from 15.4 to 29.7 cases per million per year,
affecting adults more than children of all ages, with slight female predominance, and up to
90% of children diagnosed with Henoch–Schönlein purpura (HSP/ (IgA vasculitis [IgAV)
[1]. The mean age at presentation of adult vasculitis is 47 years, while amongst children the
mean age at onset is 7 years [1, 4]. The onset of vasculitis after exposure to a trigger such as a
drug or infection is 7 to 10 days. A mean interval of 6 months can be seen between the onset
of symptoms and signs of systemic disease and the onset of secondary cutaneous vasculitis.
Almost one-half of patients presenting with cutaneous vasculitis have disease localized to the
skin without any an attributable cause, trigger or associated systemic disease, referred to as
idiopathic LCV [1]. The remainder of localized cutaneous vasculitis cases can be attributed to
recent infection and drug ingestion. LCV that results from drugs or infection is termed
hypersensitivity or allergic vasculitis. The anti-neutrophil cytoplasmic antibody (ANCA)-
associated vasculitides (AAV) vasculitis syndromes include eosinophilic granulomatosis with
polyangiitis (EGPA) (Churg-Strauss Syndrome [CSS]), microscopic polyangiitis (MPA) and
granulomatosis with polyangiitis (GPA) (Wegner granulomatosis [WG]) may first present
with cutaneous vasculitis [8] The onset of cutaneous vasculitis may be an indication of
secondary vasculitis in association with connective tissue disease (CTD) such as systemic
lupus erythematosus (SLE) vasculitis (LV), and rheumatoid arthritis (RA) the related
vasculitis (RAV) [9]. The evolution of cutaneous vasculitis occurs in three phases, (a) single
acute, self-limited episode with resolution in ? 6 months in association with drug exposure or
an infectious trigger so noted in 60% of patients; (b) relapsing disease with symptom-free
periods usually found in patients with HSP/IgAV and cryoglobulinemic vasculitis (CV) so
noted in 20% of patients; and (c) a chronic, unremitting disease most often associated with
primary systemic vasculitides, secondary vasculitides in association with CTD, CV, and
malignancy altogether in about 20% of patients [1]. The duration of vasculitis ranges from 1
week to 318 months, with mean and median durations of 28 months and 3.7 months,
respectively. Less than 20% of cutaneous vasculitis patients have extracutaneous or visceral
vasculitis. Fatal disease occurs in less than 7% of patients [1, 10].

Etiopathogenesis

A variety of injurious processes can lead to identical responses in the vessel wall
resulting in the activation of neutrophils, abnormal neutrophil diapedesis and fibrinoid
necrosis, the hallmarks of the vasculitides [1, 11]. Other morphological patterns of vasculitis
include lymphocytic endarteritis and endarteritis obliterans of transplant vascular rejection,
which are not generally associated with abundant fibrin deposits and destruction of the vessel
wall with loss of the elastic lamina [12, 13]. Adding to the difficulties in the histological

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