Autoimmune and septic vasculitis in the gastrointestinal tract – A comparative postmortem study of 38 rheumatoid arthritis patients

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Introduction: Systemic vasculitis of autoimmune origin (AV) is a basic manifestation of rheumatoid arthritis (RA). Different (acute, subacute, subchronic and chronic) stages of AV existing side by side in the same tissue sections demonstrate the relapsing nature of autoimmune vasculitis corresponding to the actual clinical activity of RA. Septic infection is one of the most serious complications of RA and can be accompanied with systemic septic vasculitis of recurrent nature (SV). Differentiation between AV and SV is of crucial importance because of different consequences and treatment. The aim of this study was to analyze the histological differences between AV and SV in blood vessels of the gastrointestinal (G-I) tract. Patients and methods: Gastrointestinal tissue samples of 33 RA patients with systemic vasculitis of autoimmune origin and 5 patients with systemic vasculitis of septic origin were analyzed histologically. Results: RA patients of both genders were affected by autoimmune or septic vasculitis at any time of the disease. Relapsing autoimmune vasculitis involved in different (nonspecific, fibrinoid necrotic or granulomatous) forms blood vessels of all sizes. Recurrent septic vasculitis involved arteries of all sizes in a nonspecific and fibrinoid necrotic form; the veins were intact. Granulomatous involvement of the veins was characteristic only for autoimmune vasculitis. Discussion and conclusion: Recognition and histological differential diagnosis of AV and SV are great challenges in surgical pathology especially in small biopsy specimens. The presence of a granulomatous type of vasculitis and involvement of the veins confirms histologically the autoimmune origin of this complication, while the lack of these supports a septic origin.