AB0347 RENAL BIOPSY IN PATIENTS WITH SYSTEMIC LUPUS ERYTHEMATOSUS: IS IT ONLY LUPUS NEPHRITIS?
Authors: E. Duran, T. Yildirim, U. Kalyoncu, A. Taghiyeva, E. Bilgin, E. Arzu Sağlam, M. Üner, J. Jabrayilov, E. C. Bolek, C. Önal, B. Farisoğullari, N. S. Koç, G. K. Yardimci, S. Girgin, G. Ayan, Z. Özsoy, G. Sandal Uzun, L. Kiliç, Ş. R. Yilmaz, A. Akdoğan, Ş. A. Bilgen, O. Karadag, S. Kiraz, B. Altun, Y. Erdem, M. Arici, A. İ. Ertenli
Journal: Annals of the Rheumatic Diseases (2021)

Background: Renal biopsy is a cornerstone in the diagnosis and management of renal involvement in patients with systemic lupus erythematosus (SLE). However, non-lupus nephritis has been also observed in SLE patients with renal disease (1). Objectives: The aim of this study was to draw attention to the causes of non-lupus nephritis in SLE patients with kidney biopsy. Methods: This retrospective, descriptive study included 139 SLE patients who had at least one kidney biopsy between 2001 and 2020. All patients had fulfilled the SLICC or EULAR/ACR criteria for SLE. According to the pathology report results, 116 of the patients were diagnosed with lupus nephritis (LN), 18 patients had non-lupus nephritis, 2 biopsies were normal, and 3 biopsies were insufficient. Demographics, SLE disease duration, and renal biopsy diagnosis were derived from our hospital medical records. Results: Of the 23 patients (female:18/male:5), the mean age at the SLE diagnosis was 30.5 years and the median SLE disease duration was 8.5 (11.6) years. Pathologic report findings were compatible with focal segmental glomerulosclerosis in 6 patients, membranous nephropathy with no cellular proliferation and inflammation in 4 patients, thrombotic microangiopathy in 3 patients, IgM nephropathy in 2 patients, tubulointerstitial nephritis in 2 patients, and proliferative glomerulonephritis with monoclonal IgG deposits in one patient. There were no different for SLE manifestation in both gropus. LN vs other renal pathologies laboratory comparing as follow: ANA (+) ≥ 1:320 89 (76.7%) vs 14 (60.9%), APS antibodies 31 (33.7%) vs 8 (57.1), anti-Sm (+) 8 (11.8%) vs 1 (4.3%) were similar for LN and other renal pathologies, but anti-ds-DNA positivity 94 (84.7%) vs 10 (50%), median ds-DNA level 421 (591) vs 150 (340) and low level of C3 and C4 were more frequent in LN (p&lt;0.001; p=0.005; p&lt;0.001, respectively).In addition, the rate of active urinary sediment and renal SLEDAI score were significantly high in LN patients. Conclusion: Various renal lesions unrelated to lupus nephritis can be observed in SLE patients. Renal biopsy plays a critical role in identifying these lesions, which may have prognostic and therapeutic implications distinctive from those of lupus nephritis. Also, anti ds-DNA positivity/level, low C3 and C4, active urinary sediment and renal SLEDAI scores may give us some clues in terms of renal pathology for SLE patients. Moreover, almost half of the patients without LN in renal biopsy have anti ds-DNA positivity. References: [1]Howell DN. Renal biopsy in patients with systemic lupus erythematosus: Not just lupus glomerulonephritis! Ultrastruct Pathol. 2017 Mar-Apr;41(2):135-146. Table 1. Demographic, clinical characteristics and results of patients with and without lupus nephritis Variables * Lupus nephritis (N=116 ) Other pathologies (N=23 ) P Age at the SLE diagnosis, years 22.5±13.1 30.5±14.5 0.006 Sex, female 93 (80.2) 18 (78.3) 0.83 SLE disease duration 8 (8.7) 8.5 (11.6) 0.27 Manifestation of SLE -Musculoscletal 75 (66.4) 14 (63.6) 0.8 -Mucocutaneous 60 (52.6) 9 (40.9) 0.31 -Hematologic 47 (40.9) 10 (43.5) 0.49 -Serosal 26 (23.2) 4 (17.4) 0.54 -Neurological 6 (5.3) 1 (4.3) 0.85 Laboratory values for kidney biopsy -Creatinine level (mg/dL ) 0.7 (0.5) 0.9 (0.6) 0.17 -GFR (ml/min ) 110 (67) 77 (65) 0.06 -24-hour urine protein ≥ 1 gr/day 72 (71.3) 17 (77.3) 0.63 ≥ 3 gr/day 36 (35.6) 11 (50) 0.23 -Active urinary sediment 91 (83.5) 6 (27.3) &lt;0.001 Renal SLEDAI at the biopsy 12 (8) 4 (4) &lt;0.001 End-stage renal disease 13 (11.2) 2 (8.7) 0.72 Renal transplantation 5 (4.3) 1 (4.3) 0.99 Exitus 8 (7) 1 (4.3) 0.99 * n (%), if otherwise specified. Med (IQR) for numerical data excluding age; mean ± SD for age. GFR: Glomerular filtration rate, LN: Lupus nephritis, SLEDAI: Systemic lupus erythematosus disease activity index Disclosure of Interests: None declared