Medium-size-vessel vasculitis

Abstract

Medium-size-artery vasculitides do occur in childhood and manifest, in the main, as polyarteritis nodosa (PAN), cutaneous PAN and Kawasaki disease. Of these, PAN is the most serious, with high morbidity and not inconsequential mortality rates. New classification criteria for PAN have been validated that will have value in epidemiological studies and clinical trials. Renal involvement is common and recent therapeutic advances may result in improved treatment options. Cutaneous PAN is a milder disease characterised by periodic exacerbations and often associated with streptococcal infection. There is controversy as to whether this is a separate entity or part of the systemic PAN spectrum. Kawasaki disease is an acute self-limiting systemic vasculitis, the second commonest vasculitis in childhood and the commonest cause of childhood-acquired heart disease. Renal manifestations occur and include tubulointerstitial nephritis and renal failure. An infectious trigger and a genetic predisposition seem likely. Intravenous immunoglobulin (IV-Ig) and aspirin are effective therapeutically, but in resistant cases, either steroid or infliximab have a role. Greater understanding of the pathogenetic mechanisms involved in these three types of vasculitis and better long-term follow-up data will lead to improved therapy and prediction of prognosis.

Fig. 1

Polyarteritis nodosa (PAN), acute phase. High-power view of skin biopsy from a 4-year-old boy with PAN. Biopsy shows a neutrophilic vasculitis affecting medium and small arteries in the deep dermis and subcutis. There is also an associated lobular panniculitis

Fig. 2

A renal angiogram from a 6-year-old girl with polyarteritis nodosa (PAN) demonstrating florid aneurysmal and nonaneurysmal changes. There are large and small aneurysms, perfusion defects, arterial cutoff and lack of crossing of peripheral renal arteries (From Brogan et al. [33] with permission)

Fig. 3

Late vasculopathy associated with polyarteritis nodosa (PAN). High-power view of histology taken from a heminephrectomy specimen (duplex system and recurrent infection) from a 4-year-old girl with classic severe PAN of 18 months duration who was in remission on treatment. Very abnormal medium-sized arteries are present, consistent with healed vasculitis with internal elastic lamina rupture, fibrosis and intimal thickening but no active vasculitis