SAT0152 Systemic and renal aa amyloidosis in rheumatoid arthritis – a comparative postmortem clinicopathologic study of 161 patients
Authors: M. Bély, Á. Apáthy
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Objectives:</h3> The <b>aim</b> of our study was to determine the prevalence and severity of <b>s</b>ystemic <b>AA a</b>myloidosis (<b>sAAa)</b>, to specify amyloid A deposits in different tissue structures of the kidneys, to outline the development of <b>r</b>enal <b>AA a</b>myloidosis (<b>rAAa</b>), and to estimate the role of <b>sAAa</b> and <b>rAAa</b> in mortality. <h3>Methods:</h3> At the National Institute of Rheumatology <b>9475</b> patients died between 1969 and 1992; among them <b>161</b> with <b>RA</b> (<b>females</b> 116, average age: 64.95 years, range 87–16, onset of RA: 50.19, average disease duration: 14.79 years; <b>males</b> 45, average age: 66.29 years, range 88–19, onset of RA: 52.57, average disease duration: 13.46 years at death); who were autopsied. <b>RA</b> was confirmed clinically according to the criteria of the ACF. <b>sAAa</b> was specified histologically, based on evaluation of <b>5</b> organs (heart, lung, liver, kidney and pancreas) in each of 161 patients. Amyloid A deposition was diagnosed histologically according to Romhányi by a modified (more sensitive) Congo red staining. Amyloid A deposits were identified in serial sections by immunohistochemical and histochemical methods. The <b>prevalence</b> (existence) and <b>severity</b> (extent) of amyloid A deposition were evaluated microscopically with an Olympus BX51 polarizing microscope. <h3>Results:</h3> <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). <b>sAAa</b> was lethal in <b>17</b> (50.0 % of 34) patients 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. <h3>Conclusions:</h3> <b>sAAa</b> is one of the main and the most insidious complications of <b>RA</b> affecting the kidneys with high prevalence and severity. <b>sAAa</b> is related to the cardiovascular system, and <b>rAAa</b> is associated with it. <b>sAAa</b> and <b>rAAa</b> may developed in both sexes, and at any time in the course of the disease. Systemic and renal amyloid A deposition is a progressive and cumulative process, involving in its early stage only a few structures in various organs, and increasingly more in the later stages of the disease. In <b>sAAa</b> the renal 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. Amyloid A deposition starts in the most frequently involved structures of the kidneys with more massive deposits. The chronology of amyloid A deposition allows an indirect assessment of the stage of renal 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 amyloid A deposition should be considered a very serious, life-threatening complication of <b>RA</b>. <h3>Disclosure of Interest:</h3> None declared