[1622] Utility of Immunofluorescence and Electron Microscopy in Renal Transplant Biopsies

Giovanna Giannico, Anthony Langone, Agnes B Fogo. Vanderbilt University Medical Center, Nashville, TN

Background: Renal biopsy is the gold standard to diagnose allograft rejection versus other causes of graft dysfunction. However, the role of immunofluorescence (IF) and electron microscopy (EM) in renal transplant biopsy diagnosis has not been well established. We therefore assessed the utility of IF and EM in this setting.
Design: We reviewed 267 transplant biopsies performed on 199 patients at Vanderbilt University Medical Center from 2003 to 2005. Pre-biopsy clinical assessment was performed by five experienced transplant nephrologists and pre-biopsy diagnosis and/or differential diagnoses were recorded on a pre-biopsy worksheet.
Results: 152 of 267 (57%) diagnoses were accurately predicted by the pre-biopsy differential diagnosis. 62 (23%) diagnoses were not predicted by clinical pre-biopsy assessment. 53 diagnoses (20%) were included in the differential diagnosis, but at least one additional significant finding was missed. Acute rejection was clinically suspected in 125 cases (47%), of which 65 (52%) were histologically confirmed, 43 (34%) showed a different histologic diagnosis, and 17 (14%) had rejection with at least one other major diagnosis. Of those cases where biopsy did not confirm clinically suspected rejection, major biopsy diagnoses were chronic allograft nephropathy (CAN) ± transplant glomerulopathy (TGP) in 46%, acute tubular injury in 31%, polyoma virus nephropathy (PVN) in 9%, thrombotic microangiopathy (TMA) in 6%, lupus nephritis (LN) in 5%, calcineurin inhibitor toxicity in 2% and minimal histologic abnormalities in 2%. The most common unpredicted diagnoses were TMA (22 cases, 8%, all unpredicted), de novo or recurrent glomerulonephritis (GN) (41 cases, 21%, unpredicted in 19) and PVN (11 cases, 6%, unpredicted in 9 cases). Clinical management and treatment strategy were altered according to biopsy results in 54% of cases.
Conclusions: Despite overall accurate clinical prediction of dignosis, renal biopsy showed unexpected findings in a significant number of cases. In addition, clinical suspicion of rejection was not confirmed in 34% of cases, thus resulting in avoidance of potential immunosuppression, or requiring a decrease in immunosuppression in patients with PVN. Thus, we conclude that IF and EM are valuable in assessment of the kidney transplant biopsy. Our data support that IF should be done routinely at least the first time the transplant is biopsied, with EM added as indicated by clinical history or abnormal LM/IF findings.
Category: Kidney (does not include tumors)

Monday, March 4, 2013 1:00 PM

Poster Session II # 222, Monday Afternoon

 

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