Electron microscopic study of an unusual posttransplant glomerular lesion

Glomerular lesions are frequently seen in renal allografts and are usually classified into transplant glomerulopathy and posttransplant glomerulonephritis. The latter is subdivided into donor-related, de novo, and recurrent glomerulonephritis. We report a distinctive posttransplant glomerular lesion that does not fit into any diagnostic category mentioned above. This lesion was characterized by the presence of global, diffuse, subepithelial, electron-lucent deposits, in addition to the usual features of transplant glomerulopathy. This unusual lesion, to the best of our knowledge, has been reported only once and, indeed, was recognized in only one of 297 renal allograft biopsy specimens in our file. Although the classification, pathogenesis, and origin of this rare lesion remain to be elucidated, it can be associated with nephrotic syndrome, deterioration of renal function, and eventual graft loss.