Background In rheumatoid arthritis (RA) systemic vasculitis (SV) is one of the main, and the most likely lethal complications to be missed clinically with high probability.
SV may cause serious complications in various organs. In the heart it may lead to multiple silent myocardial infarctions (due to coronary arteritis and/or coronary arteriolitis); in the brain it may cause microinfarcts (due to cerebral arteritis and/or arteriolitis); in the lungs multifocal transient (migratory) pneumonitis may develop as a result of pulmonary arteritis and/or arteriolitis, etc.
Objectives The aim of this study was to outline the pathogenesis of multifocal transient (migratory) pneumonia due to pulmonary medium size or small arteries and arterioles in RA.
Methods Autopsy population of 161 in-patients with RA was studied. RA was confirmed clinically according to the criteria of the ACR. SV was histologically diagnosed.
Results SV complicated RA in 36 (22.36 %) of 161 patients. Pulmonary arteritis and/or arteriolitis were present in 15 (44.1 rel%) of 34 cases (in two patients lung tissue was not available for evaluation).
Pulmonary (bronchial) arteritis and/or arteriolitis was accompanied by corresponding lobular or sublobular vasculogenic non-hemorrhagic pneumonia in 5 (3.1%) and led directly to death in 3 (1.9%) of 161 patients.
Conclusions Severe necrotizing vasculitis plays a major role in the pathogenesis of vasculogenic or so-called rheumatoid pneumonia (RhPn). Diminished blood supply due to vasculitis – distal to the involved vessels - may result in ischemia and vulnerable territories (loci minoris resistentiae) for a secondary infection (via bronchogenic or hematogenic route). According to the size of involved vessels lobular or sublobular pneumonia may develop, more or less respecting the anatomic borders of pulmonary units. The inflammation does not have a hemorrhagic character, in contrast to infarct-pneumonia due to thrombovasculitis with simultaneous venous congestion. Vasculogenic RhPn differs from bronchopneumonia as well, which is bronchocentric, has no sharply demarcated borders and is independent of the fine anatomic borders of the lung.
The size of inflammatory foci depends on the size of involved vessels; in most cases lobular or sublobular pulmonary units are inflamed (supplied by the pulmonary or bronchial small arteries or arterioles) and their diameter is usually less than 20-10 millimeters. Any forms of autoimmune vasculitis are of a relapsing (recurrent) nature, leading to the silent accumulation of inflammatory foci side by side in different stages of inflammation. The number of inflammatory foci depends on the number of involved vessels and on the frequency of repeated exacerbation of vasculitis.
Clinically it is difficult to recognize the small (silently accumulating) inflammatory foci in the lungs. The history of vasculitis, transient pulmonary complaints with or without fever may help in the diagnosis. In the patients under discussion the clinical complaints were accompanied by transient (migratory) multifocal micronodular infiltrates by X ray and reacted poorly to antibiotics. The patients died suddenly and unexpectedly of rapidly progressive cardio-respiratory insufficiency. The real vasculogenic nature of lethal RhPns was not diagnosed clinically.
Conclusion In case of multifocal, transient (migratory) pneumonia which is refractory to antibiotics, RhPn should be considered.
Disclosure of Interest None Declared
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