Transplant glomerulopathy.

Transplant glomerulopathy is the most common glomerular lesion noted in long-standing renal allografts and isografts. Morphologic examination of 328 specimens taken from 177 patients because of decreasing function revealed transplant glomerulopathy in 55, rejection glomerulonephritis in 39, de novo glomerulonephritis in 20, and recurrent glomerulonephritis in 9 patients. The most important microscopic finding is a finely lamellar thickening of the glomerular basement membrane. Endothelial swelling and mesangial proliferation are minor. Immunofluorescence is weekly positive and electron-dense deposits are missing. There is, however, subendothelial electron-lucent thickening of the lamina rara interna comparable to the lesions seen in thrombotic microangiopathy. Transplant glomerulopathy can be superimposed on other glomerular transplant lesions and is typically associated with chronic rejection; in fact it can been considered to be the glomerular equivalent of chronic vascular rejection.