FRI0026 SYSTEMIC, RENAL AND CARDIAC AA AMYLOIDOSIS IN RHEUMATOID ARTHRITIS – A COMPARATIVE POSTMORTEM CLINICOPATHOLOGIC STUDY OF 161 PATIENTS
Authors: Miklós Bély, Ágnes Apáthy
Journal: Annals of the Rheumatic Diseases (2019)

<h3>Objectives:</h3> The <b>aim</b> of our study was to determine the incidence of <b>s</b>ystemic <b>AA a</b>myloidosis (<b>sAAa</b>) in <b>RA</b>, to appraise the prevalence and severity of amyloid A deposits in different tissue structures of the kidneys and heart, to outline the development of <b>r</b>enal and <b>c</b>ardiac <b>AA a</b>myloidosis (<b>rAAa</b> and <b>cAAa</b>), and to estimate the role of <b>rAAa</b> and <b>cAAa</b> in mortality. <h3>Methods:</h3> <b>One hundred sixty one</b> (<b>161</b>) non- selected autopsy patients with rheumatoid arthritis (<b>RA</b>) were studied. <b>RA</b> was confirmed clinically according to the criteria of the <b>ACR</b> [1]. <b>sAAa</b> was specified histologically, based on evaluation of <b>5</b> organs (heart, lung, liver, kidney and pancreas). Amyloid A deposition was diagnosed histologically according to Romhányi by a modified (more sensitive) Congo red staining [2]. Amyloid A deposits were confirmed in serial sections by immunohistochemical and histochemical methods. Results: <b>sAAa</b> complicated <b>RA</b> in <b>34</b> (<b>21.12</b>%) of 161 patients; in <b>127</b> (<b>78.88</b>%) of 161 patients amyloid A deposits were not found. Amyloid A deposits were found in <b>29</b> (<b>87.88</b>%) <b>kidneys</b> of 33 patients <b>with sAAa</b>; kidneys were negative for amyloid in <b>4</b> (<b>12.12</b>%) of 33 cases (in 1 of 34 patients with <b>sAAa</b> tissue blocks of kidneys were not available). Amyloid A deposits were found in <b>29</b> (<b>87.88</b>%) <b>hearts</b> of 33 <b>with sAAa</b>; the heart was negative for amyloid in <b>4</b> (<b>12.12</b>%) of 33 cases (the heart of one patient with <b>sAAa</b> was not available). Renal amyloid A deposition led to death in <b>17</b> (50.0% of 34) patients <b>with sAAa</b> due to massive amyloid A deposition in the kidneys, leading to renal insufficiency and uremia. Cardiac amyloid A deposition led to death in <b>3</b> (8.82% of 34) patients <b>with sAAa</b> (and contributed to the lethal outcome in further 5). <b>Forteen</b> (41.18% of 34) patients with <b>sAAa</b> died of other causes such as peritonitis, lethal septic infection, etc. <b>sAAa</b> was clinically diagnosed in <b>9</b> (26.47%) and missed in <b>25</b> (73.52%) of 34 patients, and only cases with massive renal amyloid A deposits were recognized. Cardiac <b>AAa</b> or its pathogenic role in mortality was not diagnosed. Conclusion: <b>sAAa</b> is one of the main and the most insidious complications of <b>RA</b> affecting the kidneys and heart with high prevalence and severity. <b>sAAa</b> is related to the cardiovascular system, and <b>rAAa</b> or <b>cAAa</b> are associated with it. <b>sAAa</b>, <b>rAAa</b> and <b>cAAa</b> may developed in both sexes, and at any time in the course of the disease. Systemic, renal and cardiac amyloid A deposition is a progressive and cumulative process, involving in its early stage only a few structures in some organs, and increasingly more in the later stages of the disease. In <b>sAAa</b> the renal and cardiac amyloid A deposition starts after a latent stage. This latency may be caused by a not specified local protective mechanism, e.g. great excretion capacity of the kidneys, due to motility of the heart or oxygenisation etc. Amyloid A deposition starts in the most frequently involved structures of the kidneys or heart with more massive deposits. The chronology of amyloid A deposition allows an indirect assessment of the stage of renal or cardiac amyloidosis, which may have a prognostic value in everyday surgical pathology. Half of the patients with <b>sAAa</b> died of uremia caused by massive <b>rAAa</b> and only 9 of these were clinically recognized. Renal and cardiac amyloid A deposition should be considered a very serious, life-threatening complication of <b>RA</b>. <h3>References:</h3> [1] Arnett FC, et al: Arthritis Rheum, 1988; 31: 315-324. DOI: 10.1002/art.1780310302 [2] Bély M, Makovitzky J: Acta Histochemica 108, 175-180 (2006). DOI: 10.1016/j.acthis.2006.03.017 <h3>Disclosure of Interests:</h3> None declared