POS-722 SPECTRUM OF RENAL ALLOGRAFT BIOPSY – A SINGLE CENTRE EXPERIENCE

Abstract

Histopathology plays a key role in diagnosis of graft dysfunction in transplant recipients. Apart from graft rejection, many patients are having recurrence of native kidney disease and infections causing graft dysfunction. In this study, we would like to describe the different histopathological profile of transplant kidney biopsy in our centre. We had conducted a retrospective descriptive study of all transplant kidney biopsies which were performed between Jan 2014 to Nov 2020 in a tertiary care hospital. From the registry, age, sex, duration since transplant and histopathological diagnosis were collected and analysed. Total number of biopsies performed were 587 in the past seven years. Males were 81.3% (n=477). Patients with age less than 20 were 4.9% (n=29), 21 to 40 years were 75.2% (n=441) and 41 to 60 years were 19.9% (n=117). None of them were more than 60 years of age. Duration since transplant was analysed for these biopsies. Patients with less than 1 month, 1month to 3 months, 3 months to 1 year and more than 1 year were 180 (30.6%), 92 (15.7%), 120 (20.4%) and 195 (33.2%) respectively. Due to the presence of multiple pathologies in a biopsy, a total of 649 pathologies were found. Cellular and humoral rejections were 32.2% and 13.6% respectively. Across these timelines since transplant, cell mediated rejections (CMR) (34.5%, n=72) and antibody mediated rejections (ABMR) (50%, n=44) were more seen during >1 year post transplant. Apart from these, incidence of glomerular, interstitial and vascular pathologies found which were described in table 1 below. IgA Nephropathy and Thrombotic Microangiopathy (TMA) were most seen glomerular pathology (n=19,2.9%) followed by Focal segmental glomerulosclerosis (FSGS) (n=17,2.6%). Crescentic IgA Nephropathy was seen in 2 patients who had IgA Nephropathy as native kidney disease. 2,8-Dihydroxy Adenine Crystalline (DHA) Nephropathy was diagnoed at 10 months post transplant in one patient whose native kidney disease was not known. Out of 587 biopsies, 9 were preimplantation and 12 were followup protocol biopsies. In the preimplantation biopsy, 6 were normal and 3 were Acute Tubular Injury (ATI). Special stains for SV 40 and CMV were used in 14 and 2 patients respectively. Two patients had SV 40 and one had CMV positivity among them. Electron microscopy was done in 6 patients. Four of them had diffuse effacement of podocyte foot processes whereas, in light microscopy 3 had minimal change pattern of injury and one had FSGS. One had subepithelial and mesangial electron dense deposits with Membranoproliferative Glomerulonephritis(MPGN) in light microsopy and the other had mesangial electron dense deposits / effacement of foot processes of podocyte with IgA Nephropathy / Collapsing Glomerulopathy in light microscopy. Complications encountered post biopsy were perinephric hematoma and hematuria. One patient with perinephric hematoma had blood clots passed in urine which caused hydroureteronephrosis and then resolved with conservative management. In our series, CNI Toxicity was seen in 26.8% (n=174), Infection in 4.2% (n=27), Rejection in 46.8% (n=304), Glomerulonephritis in 12.2% (n=79) and other pathologies in 10% (n=65) of the allograft biopsies performed.