Background Systemic vasculitis of autoimmune origin (A-SV) is of critical importance in the pathogenesis of rheumatoid arthritis (RA). RA may be complicated by septic infections (SI) accompanied with systemic vasculitis of septic origin (S-SV). The correct clinical diagnosis of A-SV and S-SV is essential because of essential differences in therapy.
Objectives The aim of this study was to characterize the A-SV and S-SV by the type, incidence and severity of vasculitis involving blood vessels of different caliber.
Methods At the National Institute of Rheumatology 12138 patients died between 1969 and 2000; among them 234 with RA and all of them were autopsied. RA was confirmed clinically according to the criteria of the ACR. Lethal septic infection (SI) was observed in 31 (13.25%) of 234 patients. SI was accompanied in 5 patients with S-SV. The clinically identified pathogenic agents and the strong, significant and positive correlation between S-SV and SI (association coefficient: 1, c2=26.1881, p<0.00007) supported the infectious origin of SV.
The average incidence and severity of S-SV in twelve organs of these 5 RA patients was analyzed and compared with 33 RA patients with A-SV of our previous study . The negative value of association coefficient and the lack of significant correlation between A-SV and lethal SI (association coefficient: -0.3249 c2=0.6052, p<0.44) supported the direct autoimmune origin of SV in patients without SI .
The incidence (existence), severity, and the types of vasculitis (non- specific – Ns, fibrinoid necrotic – Fn, granulomatous – Gr) in blood vessels of different calibers (arteriole – a, small artery – A, medium size artery – AA, venule – v, small vein – V, medium size vein – VV) were determined visually in histological slides . Severity of vasculitis was evaluated by semi-quantitative, visual estimation on a 0 to 3 plus scale (based on the number of involved vessels/light microscopic field x40).
Results The incidence and severity of A-SV and S-SV in absolute number is summarized in Table.
Conclusions The clinical course of RA characterized by acute exacerbations and relapses corresponds to the relapsing nature of autoimmune vasculitis. A-SV and S-SV may exist in different stages of inflammation at the same time . A-SV is more severe and shows variegated histologic changes, versus S-SV which is less severe and more monotonous.
Non-specific and fibrinoid necrotic vasculitis may exist in A-SV and S-SV as well. Granulomatous vasculitis was never detected in S-SV; the presence of granulomatous vasculitis refers to A-SV.
Arteries of all calibers may be involved in both systemic vasculitis with more pronounced involvement of medium size arteries in S-SV. Veins were never involved in S-SV; the inflammation of veins supports A-SV.
Histological differences may help in identification of autoimmune or septic origin of vasculitis.
Bély M, Apáthy Άgnes. Clinical pathology of rheumatoid arthritis: Cause of death, lethal complications and associated diseases in rheumatoid arthritis. 1–440 pp. Akadémiai Kiadό, Budapest 2012 http://www.akkrt.hu/p>
Disclosure of Interest None declared
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