Vasculitis from the Pediatric Perspective P. A. Brogan, MD and M. J. Dillon, MD Address The Institute of Child Health, 30 Guildford Street, London W C1N 1EH, United Kingdom. E-mail: m.dillon@ ich.ucl.ac.uk Current Rheumatology Reports 2000, 2:411–416 Current Science Inc. ISSN 1523–3774 Copyright © 2000 by Current Science Inc. Introduction Vasculitis occurs in many different diseases and syndromes in childhood [1]. It is the predominant manifestation of the disorder in some; in others, however it may be one aspect of a more widespread disease [2,3]. A classification that has been proven useful based on that of Fink [4] is outlined in Table 1. Polyarteritis Nodosa, Microscopic Polyangiopathy, and Cutaneous Polyarteritis The classic form of polyarteritis, polyarteritis nodosa (PAN), is a necrotizing vasculitis associated with aneurysmal nod- ules along the walls of medium-sized muscular arteries [5]. Although there is an overlap with smaller vessel disease, it is distinct from microscopic polyangiopathy and occurs more commonly in childhood than this latter disorder [5]. The main clinical features are malaise, fever, skin rash, abdominal pain, and arthropathy [5,6]. Other features include testicular pain, myalgia, hypertension, neuropathy, renal failure, organic psychosis, and myocardial ischemia [5–7]. Visceral angio graphy plays a key ro le in the diagno sis [8–10]. Microscopic polyarteritis differs from classic PAN by the presence of extensive glomerular involvement, and may be defined as small-vessel vasculitis with focal seg- mental glomerulonephritis but without granulomatous disease of the respiratory tract [11]. Clinically, it can be dif- ficult to distinguish from Wegener’s granulomatosis, and it often presents with rapidly progressive glomerulonephritis [12] in association with perinuclear antineutrophil cyto- plasmic antibody (pANCA) positivity. Treatment for both macroscopic and microscopic pol- yarteritis consists of steroids, antiplatelet agents, and an additional cytotoxic agent (ordinarily cyclophosphamide) [13•,14]. Cyclophosphamide is usually administered orally for 2 to 3 months at 2 mg/kg/d to induce remission [15•]. Pulsed intravenous cyclophosphamide may have advantages over the oral route in reducing the total cumu- lative dose and hence side effects, but it may not be as effective as the daily oral regimen in aggressive disease for the prevention of relapses [16]. Maintenance therapy is usually with oral azathioprine at a dose of 2 mg/kg/d, with low-dose alternate day prednisolone (0.2–0.5 mg/kg), and antiplatelet agents. If remission with this regimen is not maintained, then cyclosporin or mycophenolate mofetil may prove useful, although the published evidence for the use of these agents in this context is lacking. Currently, the mortality for polyarteritis nodosa at Great Ormond Street Hospital, London is about 10%, which compares favorably with many adult series [5,15•]. Cutaneous polyarteritis is a syndrome associated with crops of painful skin nodules, livedo reticularis, and often with a story of preceding upper respiratory tract infection [17–19]. The condition responds to nonsteroidal anti- inflammatory drugs but can require steroids. If the condi- tion is streptococcus induced, prophylactic penicillin has a role. Cutaneous vasculitis usually runs a benign course, although in some patients the cutaneous features evolve into systemic polyarteritis nodosa. Relapses, particularly in association with recurrent streptococcal infection are seen in up to 25% of cases. Clinicians seeing this condition usu- ally advise continuing penicillin prophylaxis throughout childhood to prevent relapses because it is among the relapsing group that systemic vasculitis tends to occur. Kawasaki Disease This systemic childhood vasculitis was first described by Tomisaku Kawasaki in Japan in 1967 [20]. More than 116,000 cases have subsequently been reported from that country alone [21], but the disease is of world-wide distri- bution and mainly affects infants and young children This article reviews the spectrum of vasculitic illness affect- ing children. Apart from the relatively common vasculitides (H enoch-Schönlein purpura, Kawasaki disease, and in worldwide terms Takayasu disease) there are a number of important but comparatively rare disorders affecting children. As in adults, there is a considerable degree of overlap between the various vasculitic syndromes in child- hood. W ith modern therapeutic agents, the prognosis for many of the childhood vasculitides has improved; however, in spite of this, there remains a not inconsequential morbid- ity and mortality. It is anticipated that as our knowledge of the immunopathogenesis of this group of disorders expands, classification and treatment of vasculitis in both children and adults will improve.