 |
|
|
 |
Renal Amyloidosis in Rheumatoid Arthritis To the Editor: Dr. Uda, et al reported 2 distinct clinical courses of renal AA amyloidosis in patients with rheumatoid arthritis (RA)1. Their findings are of considerable interest; however, a few comments regarding the selection of patients and the authors' conclusions may be important. The authors performed duodenal biopsy in patients with RA who did not present with renal manifestations. Those patients who had positive duodenal biopsies for amyloidosis had renal biopsies. Those who were positive for amyloid renal biopsies have been followed for up to 5 years and the survival was estimated. According to the authors, 53 of 524 patients with RA (~10%) had renal biopsies positive for amyloid. Thirty-eight of 53 patients (72%) were followed up. In the abstract, the authors stated that in 27 patients, amyloid was found exclusively in the glomeruli, and in 11, in the blood vessels only. However, in the Results section (page 1483, last paragraph on the left) they stated that among 27 patients, the amyloid was exclusively found in the glomeruli in 7 cases only, and in the other 20, a mixed pattern (glomerular/vascular) was found. This statement seems to contradict the abstract. In Figure 3, it was not clear whether the curves apply to 7 and 11 patients or to 27 and 11. If the curves apply to 7 and 11 patients, then another (third) curve showing a mixed pattern in 20 patients would be appropriate. It would be of interest to know if some control patients with RA with negative duodenal biopsy had renal biopsy. AA amyloid does not necessarily have to be present simultaneously in the duodenum and the kidney. It would also be appropriate to state in the Methods what was the minimal number of glomeruli in the biopsy that the authors considered sufficient for diagnosis. Nephropathologists require minimum of 5 or even 10 glomeruli for correct diagnosis. Regarding the diagnosis of AA amyloid, it would be of interest to stain renal biopsies for kappa, lambda, and immunoglobulin chains and to do serum immunofixation electrophoresis, since in some cases mixed AL and AA amyloidosis can be present. Finally, perhaps in some patients, renal biopsies were performed at the end of the followup. If so, it would be of interest to know whether the initial pattern persisted. WALDEMAR PRUZANSKI, MD, FRCPC, FACP, FACR, Professor of Medicine (Em), University of Toronto, Toronto, Canada. Address reprint requests to Dr. W. Pruzanski, Rosedale Medical Centre, 600 Sherbourne Street, Suite 803, Toronto, Ontario M4X 1W4, Canada. E-mail: drwpruzanski@bellnet.ca 1. Uda H, Yokota A, Kobayashi K, et al. Two distinct clinical courses of renal involvement in rheumatoid patients with AA amyloidosis. J Rheumatol 2006;33:1482-7. |