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AB0630 Severity of Systemic Vasculitis in Rheumatoid Arthritis and Progressive Systemic Sclerosis – A Comparative Postmortem Study

Background The vascular system is the most important target of immunological processes, manifesting as vasculitis or characteristic structural changes of blood vessels. Vasculitis and/or structural changes of blood vessels are the basic light microscopic hallmark of autoimmune diseases. Most of the characteristic histological changes in various organs may be regarded as a direct consequence of vasculitis. Objectives The aim of this study was to determine post mortem the severity of systemic vasculitis (SV) in rheumatoid arthritis (RA) and progressive systemic sclerosis (SSc) patients, respectively. Methods Twelve organs (heart, lung, liver, spleen, kidneys, pancreas, gastrointestinal tract, adrenal glands, skeletal muscle, peripheral nerve, skin and brain) of 36 RA and of 11 SSc in-patients with SV were studied microscopically. RA and SSc were confirmed clinically according to the criteria of the American College of Rheumatology (ACR). SV was determined histologically. The “severity” of vasculitis was evaluated by semi-quantitative visual estimation on a 0 to 3 plus scale, based on the number of involved blood vessels per light microscopic field (x40 objective of an Olympus BX51). Results The average value of severity SV/patient in 36 RA and in 11 SSc patients was different. In RA the average value of severity/patient was appreciably lower (0.276), than that of SSc patients (1.145). In RA patients the number of involved organs varied: not all examined organs were involved and the prevalence (incidence and severity) of vasculitis in each organ was different. In SSc patients SV was present in each of the investigated organs, with different incidence and severity. In RA, 5 of 36 patients (13.9%) had extremely severe (average value of severity/RA patient with SV >0.630); and 31 of 36 patients (86.1%) had a mild, or moderate degree of SV (average value of severity/RA patient with SV <0.455) (1). In SSc 2 of 11 patients (18.2%) had extremely severe (average value of severity/SSc patient with SV >1.75); and 9 (81.8%) had a mild, or moderate degree of SV (average value of severity/SSc patient with SV <1.2 (2). The “severity” of vasculitis showed a step-wise growth curve in both diseases according to increasing average values of vasculitis/patient. There was no gradual transition between the “extremely severe” and “mild or moderate degree” of SV. Conclusions The severity of vasculitis in RA and SSc patients, arranged according to the increasing value of “average severity” of vasculitis, in both diseases showed step-wise intensity. This step-wise change without gradual transition suggests that different (genetic, immunologic etc.) factors may play a role in determining the severity of vasculitis. Conceivably, the pathogenesis of mild and extreme severe vasculitis in both diseases may be different. References Bély M: Krankheitsmodifizierende Faktoren bei chronischer Polyarthritis. D.Sc. Thesis, Budapest 1993. Apáthy Άgnes, Bély M: Mortality and histological characteristics of SSc. Annals Rheum Dis 66. Suppl.II. 198-199 (2007) http://www.abstracts2view.com/eular/ Disclosure of Interest None declared DOI 10.1136/annrheumdis-2014-eular.1236