Objectives Systemic vasculitis (SV) followed by chronic degenerative (ischemic) and progressive (fibrotic) changes is a basic complication of rheumatoid arthritis (RA) and of progressive systemic sclerosis (SSc).
The aim of this study was to compare the SV, according to the type of vasculitis and involved blood vessels of different sizes, in RA and SSc.
Methods Twelve organs (heart, lung, liver, spleen, kidneys, pancreas, gastrointestinal tract, adrenal glands, skeletal muscle, peripheral nerve, skin and brain) of 36 RA and and 11 SSc in-patients with SV were studied.
RA and SSc were confirmed clinically according to the criteria of the ACR. The type of vasculitis and the size of involved vessels were determined histologically.
Results: SV was present in the investigated organs with different incidence.
In RA three types of vasculitis were observed: non-specific (Ns), fibrinoid necrotic (Fn) and granulomatous (Gr), which existed in different (acute-subacute-subchronic-chronic) stages.
In SSc only two types of vasculitis or vascular changes were present, non-specific (Ns) and fibrinoid necrotic (Fn) vasculitis, each with or without progressive fibromuscular and/or intimal proliferation and successive adventitial fibrosis (FIP).
Vessels of all sizes, arterioles (a), small arteries (A), medium size arteries (AA), venules (v), small veins (V), and medium size veins (VV) were involved, with varying incidence in both diseases (capillaries were not evaluated).
Average values of incidence in RA and SSc patients with vasculitis (based on the absolute number of involved vessels in all investigated organs)
Conclusions The presence (existence) of SV was more prominent in SSc than in RA (total sum of incidence in 11 SSc patients: 38.64 versus 36 RA patients: 9.56).
In both diseases non- specific vasculitis was dominant; in RA (67.1% of the total sum) existing in different (acute-subacute-subchronic-chronic) stages and in SSc (71.8%) with or without accompanying fibromuscular and/or intimal proliferation and successive adventitial fibrosis.
Fibrinoid necrotic type of vasculitis was relatively frequent in SSc (28.2% of the total) in comparison with RA (19.8%).
Granulomatous type of vasculitis was not found in SSc; granulomatous vasculitis is not characteristic of SSc.
Non-specific or fibrinoid necrotic vasculitis combined with fibromuscular and/or intimal proliferation and successive adventitial fibrosis are supporting the diagnosis of SSc. FIP in its typical form was never present in RA, FIP is not characteristic of RA.
Blood vessels of all sizes may be involved in both diseases: dominant involvement of arterioles and small arteries is characteristic of RA and the relative high prevalence in veins is characteristic of SSc. (Regarding a:51.5 and A:32.6% in RA versus a:35.5 and A:27.3% in SSc, regarding v:1.7, V:2.6 and VV:0.9% in RA versus v:7.5, V:9.7 and VV:8.0% in SSc)
Histological difference in the types of vasculitis or vascular changes, and the size of the involved blood vessels, may help in the identification of certain autoimmune disorders.
Disclosure of Interest None Declared