Crystal-associated nephropathy in patients with brushite nephrolithiasis.
BACKGROUND
We have biopsied the renal cortex and papillae of patients who form brushite renal stones asking if this unusual stone type is associated with specific tissue changes. We contrasted these with biopsies of 15 calcium oxalate stone formers, three stone formers with intestinal bypass, and four normal subjects.


METHODS
We studied all ten brushite stone formers treated with percutaneous nephrolithotomy (PNL) during the past 3 years using digital video imaging of renal papillae, and obtained cortical and papillary biopsies. Biopsies were analyzed by light and electron microscopy, microinfrared spectroscopy, and electron diffraction.


RESULTS
Apatite crystals plugged scattered terminal collecting ducts whose cells were injured or dead, and surrounding interstitium inflamed and fibrotic. White papillary deposits of interstitial apatite particles, so called Randall's plaque, were also present. Glomerular changes and cortical tubular atrophy and interstitial fibrosis were moderate to severe.


CONCLUSIONS
Brushite stone formers combine the interstitial plaque of calcium oxalate stone formers with the collecting duct apatite plugs found in stone formers with intestinal bypass. Collecting duct injury and interstitial fibrosis are severe. Prominent cortical fibrosis, tubule atrophy, and glomerular pathology seem secondary to the collecting duct plugging. We believe crystallization obstructs and destroys terminal collecting duct segments thereby damaging nephrons, perhaps via intranephronal obstruction, and producing a hitherto unrecognized renal disease.
Evan
Andrew P
AP
Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, Indiana 46220, USA. evan@anatomy.iupui.edu
Lingeman
James E
JE
Coe
Fredric L
FL
Shao
Youzhi
Y
Parks
Joan H
JH
Bledsoe
Sharon B
SB
Phillips
Carrie L
CL
Bonsib
Stephen
S
Worcester
Elaine M
EM
Sommer
Andre J
AJ
Kim
Sam C
SC
Tinmouth
William W
WW
Grynpas
Marc
M
D000293:Adolescent; D000328:Adult; D001031:Apatites / Q000378:metabolism; D002130:Calcium Phosphates / Q000378:metabolism*; D002648:Child; D003460:Crystallization; D004847:Epithelial Cells / Q000473:pathology; D005260:Female; D005355:Fibrosis; D006801:Humans; D007668:Kidney / Q000473:pathology; D007669:Kidney Calculi / Q000473:pathology*; D007674:Kidney Diseases / Q000209:etiology*; D008297:Male; D008875:Middle Aged
D001031:Apatites; D002130:Calcium Phosphates; C494366:calcium phosphate, dibasic, dihydrate