Background Rheumatoid arthritis (RA) and psoriatic arthritis (PsA), like all chronic autoimmune arthritides, may be complicated by AA amyloidosis (AAa).
Objectives The aim of this study was to determine the prevalence and extent of AAa in RA and PsA patients, furthermore appraise the extent of amyloid A deposits in various organs.
Methods At the National Institute of Rheumatology 11860 patients died between 1968 and 1998; among them 161 patients with RA and 12 with PsA. All of them were autopsied. RA and PsA were diagnosed clinically according to the criteria of the ACR [1,2].
Amyloid deposits on different tissue structures [arteriole, small artery, medium size artery, venule, small vein, medium size vein, interstitial collagen fiber, reticulin fiber (collagen IV), basal laminas, nerve, renal glomerulus] of 6 organs [heart, lungs, liver, kidney, skin and brain] were determined histologically.
The extent of amyloid A deposition was evaluated by semi-quantitative, visual estimation on a 0 to 3 plus scale, based on the number of involved tissue structures per light microscopic field . (“0”: no amyloid deposits, “1”: Sporadic, minimal amyloid deposits on different tissue structures, “2”: less than five, “3”: five or more involved tissue structures per microscopic field at objective magnification of x20)
The average prevalence and extent of amyloid A deposits of RA and PsA patients and the average prevalence and extent of amyloid A deposits in various organs were compared by Student (Welch) t-probe.
Results The prevalence (in %) and the average extent of amyloid A deposits (absolute value) in various organs of RA and PsA patients are summarized in Table 1.
Conclusions Based on the nearly same 0,585 versus 0.668, significantly not different: p<0.198) average amount of amyloid A deposits/patient, the immune processes (producing amyloid A deposition) of our RA and PsA patients may be similar.
The more prominent amyloid deposition in the lungs of RA patients (in contrast with PsA patients) may be associated with more frequent and pronounced pulmonary complications of RA (vasculitis, interstitial pneumonitis and fibrosis, etc.), than by PsA.
Extreme severe amyloid deposition in the skin of PsA patients may be due to local factors, namely severe systemic dystrophic changes of the skin in psoriasis. A diverse affinity of amyloid A to qualitative changed collagens cannot be ruled out in PsA in comparison with RA. In systemic sclerosis patients such change of collagens has been demonstrated .
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Disclosure of Interest None declared
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