Epithelial cell clusters of distal convoluted tubules in end-stage chronic glomerulonephritis

Differences in the pathologic changes of the proximal convoluted tubules, the cortical segments of the thick ascending limbs of the loops of Henle, and the distal convoluted tubules in the end-stage kidneys with chronic glomerulonephritis were studied by means of both light and electron microscopy. Kidneys with chronic glomerulonephritis were obtained from 8 non-dialyzed patients at autopsy and 9 dialyzed patients at the time of nephrectomy prior to renal transplantation. Epithelial cell clusters with clear cytoplasm, decreases in the luminal and outer diameters of the tubules, and thin basement membranes were observed in both the non-dialyzed and dialyzed kidneys to varying degrees. The epithelial cell clusters were more extensive and distinct in kidneys from patients with a long history of chronic glomerulonephritis and/or long-term hemodialysis. Electron microscopy of the epithelial cell clusters revealed the absence or narrowing of lumens and luminal surfaces that were smooth except for a few short microvilli. Observation of serial sections showed that these epithelial cell clusters were derived from the distal convoluted tubules belonging to obsolescent glomeruli. This form of tubular change is quite different from the well-known atrophy of the proximal convoluted tubules belonging to obsolescent glomeruli in chronic glomerulonephritis.