P0424CLINICO-PATHOLOGICAL CHARACTERISTICS AND OUTCOMES OF PATIENTS WITH DNAJB9 POSITIVE FIBRILLARY GLOMERULONEPHRITIS

Abstract

Abstract Background and Aims To investigate the clinicopathological features and prognosis of DNAJB9 positive fibrillary glomerulonephritis (FGN) in a single center in China. Method Cases diagnosed as FGN by renal biopsy from January 2011 to December 2019 in Jinling Hospital were stained with anti-DNAJB9 by immunohistochemistry. The patients with DNAJB9 positive FGN were retrospective analyzed. Results DNAJB9 staining of glomerular deposits was seen in 6 cases of FGN. 1 man and 5 women with a median age of 26 years (range, 21 to 49 years) were studied. Underlying autoimmune disease of Sjogren's syndrome and Hashimoto thyroiditis was in 1 case. None of them had dysproteinemia, malignancy, hepatitis C, hepatitis B, cryoglobulinemia, or diabetes. The patients presented with hypertension and edema in 5 cases, renal insufficiency in 1 case, and proteinuria in 6 cases with the median 24-hour urine protein 2.58 g (range, 1.66 to 9.57 g), nephrotic syndrome in 3 cases, and microscopic hematuria in 2 cases. The histologic pattern was mesangial proliferative glomerulonephritis (GN) and membranoproliferative GN. A mean of 9.7% of glomeruli were globally sclerotic. Crescents were present in 1 case (10%). The degree of tubular atrophy and interstitial fibrosis were absent (2 cases) and mild (4 cases), and severe acute tubular injury was in 1 case. All 6 cases showed glomerular positivity for IgG, C3 and C1q, 5 of which were positive for IgM, and 4 of which were positive for IgA. The glomerular deposits stained for polyclonal IgG subclasses and both kappa and lambda light chains in 3 cases. In 1 case, it stained for polyclonal IgG subclasses without kappa or lambda. IgG subclasses were IgG4 dominant in 3 cases and IgG1 dominant in 1 case. In 2 cases, they stained for monoclonal IgG1-kappa and IgG1-lambda. On electron microscopy (EM), the fibrillary deposits were seen infiltrating the mesangium, subendothelial, subepithelial area in all 6 cases, and the lamina densa of the GBMs in 5 cases with diameter of 7-40nm. Combined with observation of DNAJB9 staining, immunofluorescence microscopy and EM, extraglomerular deposits were identified in vessel walls in 5 cases, tubular basement membranes in 3 cases, peritubular capillaries in 3 cases. Congo red positivity was in 4 cases. At a median time of 32.9 months (range, 1 to 68.3 months) after biopsy, 3 cases were stable, 1 case had partial renal function recovery, and 2 cases had partial remission of proteinuria. Conclusion DNAJB9 immunohistochemistry is sensitive and specific for FGN. Monoclonal IgG and light chain was observed in young patients. Extraglomerular deposits were common. Prognosis was good in this young patient’s series.