[1957] Ultrastructural Features of Transplant Glomerulopathy: The Role of Electron Microscopy in Early Diagnosis.

Muhammad A Raza, Randy Tashjian, Hong Qu. St. John Hospital and Medical Center, Detroit, MI

Background: Transplant glomerulopathy (TG) is a pathologic condition of renal allografts that is now recognized as a distinct entity from other forms of chronic allograft damage.TG has been associated with circulating antidonor human leukocyte antigen (HLA) antibodies and the deposition of the complement split product C4d in peritubular capillaries (PTCs), suggesting antibody-mediated mechanism. The light microscopic alterations that develop during the course of this condition is characterized by double contours of glomerular basement membrane (GBM). Early TG is best identified by electron microscopy (EM), which can detect separation of endothelium from GBM before the establishment of GBM duplication and mesangial interposition. The purpose of this study was to determine the effectiveness of EM in the diagnosis of early TG.
Design: To assess the value of EM in early TG, we conducted a retrospective study on 162 graft biopsies obtained at our institution from 2008–2009. Each case was review by EM and interpretation was based on subendothelial space widening {Figure 1), GBM duplication (Figure 2), and mesangial interposition.

Results: Of the 162 biopsies, 58 (36%) exhibited TG by light microscopy, of which 47 (81%) demonstrated early developing TG as detected by EM. The remaining 115 biopsies were negative for TG by light microscopy, but EM unveiled evidence of TG in 13 (11%) of these cases. In addition, of the 47 cases of early TG, 34 (72%) stained positively with C4d in PTCs.
Conclusions: In summary, sole dependence upon light microscopy with periodic acid-schiff and silver special stains in the evaluation of TG may yield false positive or false negative results. Furthermore, positive staining of PTCs with C4d may not always be present in patients suffering from TG. Subendothelial space widening is the most reliable and reproducible feature of TG and is best detected by EM, even if examination by light microscopy is unremarkable.
Category: Ultrastructural

Wednesday, March 2, 2011 9:30 AM

Poster Session V # 276, Wednesday Morning


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