Phospholipase A2 Receptor Staining (PLA2R) Is Very Rare in De Novo Membranous Glomerulopathy in the Renal Transplant
Christopher P Larsen, Patrick D Walker. Nephropath, Little Rock, AR; University of Arkansas for Medical Sciences, Little Rock, AR
Background: Membranous glomerulopathy (MG) is one of the most common glomerulonephritides involving the renal transplant. Since many patients never have a tissue diagnosis of their native kidney disease, it is often not possible to definitively determine whether MG in the transplant setting is a recurrent or de novo process. Therefore, we sought to determine the utility of PLA2R staining for the detection of recurrent MG. We also compared the morphologic features of the two groups in order to determine if there is increased evidence of antibody-mediated rejection in the de novo group, as some have recently reported.
Design: 105 cases of MG occurring in renal transplant biopsies were identified. Only biopsies from patients with a tissue diagnosis of the primary native renal disease were included in this study and included: 12 MG, 3 diabetes mellitus, 3 focal segmental glomerulosclerosis, 3 polycystic kidney disease, 1 IgA nephropathy, 1 anti-GBM antibody disease, and 1 with renal congenital abnormalities. There were 12 biopsies from 11 patients with recurrent MG and 12 biopsies from 11 patients with de novo MG.
Results: De novo MG occurred at mean 43 months post transplant (range 2-190 months) and recurrent MG at mean 63 months post transplant (range 1-131 months). 10/12 (83%) recurrent MG and 1/12 (8%) de novo MG biopsies showed positive glomerular staining for PLA2R giving PLA2R a sensitivity of 83% (95% CI 51-97%) and specificity of 92% (95% CI 60-100%) for recurrent MG. 2/12 (17%) de novo and 1/12 (8%) recurrent biopsies showing the presence of microcirculation inflammation (MCI). Peritubular capillary (PTC) C4d staining was negative in all cases. Cell mediated transplant rejection was seen in 2/12 (17%) de novo and 2/12 (17%) recurrent MG. 1/12 (8%) de novo MG and 0/12 (0%) recurrent MG had BK nephritis. Mesangial deposits were present in 1/12 (8%) recurrent and 5/12 (42%) de novo. There was one case of recurrent MG with a follow-up biopsy which showed negative PLA2R staining at 1 month post transplant (stage 0) and 3+ positive staining at 16 months post transplant.
Conclusions: Recurrent MG is strongly correlated with PLA2R positivity with a sensitivity of 83% and specificity of 92% for recurrent MG. There was no morphologic evidence of an association between antibody mediated rejection and de novo MG as both groups had a similar degree of MCI and PTC C4d staining. Most interestingly, PLA2R staining was almost always negative in de novo MG, suggesting a different mechanism in this unique form of MG.
Category: Kidney (does not include tumors)
Tuesday, March 5, 2013 11:45 AM
Proffered Papers: Section H, Tuesday Morning