Wang H, Kjellstrand CM, Cockfield SM, Solez K
How much tissue is needed for accurate diagnosis with renal
biopsies
Am Soc Nephrol
J Am Soc Nephrol (abstract)
(Sep) 7:1784 1996
The minimum renal biopsy specimen size needed to optimize the chances of
rendering a meaningful diagnosis has not been determined. This issue can
evoke quite a lively debate specially witht the recent introduction of thin
gauge spring-loaded biopty needles. Wang et al set out to address the
problem.
Material: 199 baseline biopsies obtained at time of transplantation and 114
subsequent core biopsies in the same patients. Three features were
investigated:
1) Glomerulosclerosis (GS), 2) chronic tubulointerstitial damage (IF) and
arteriolar hyalinosis (AH) regarding their influence on outcome (defined as
allograft loss Carl M. Kjellstrand, M.D., personal communication).
Baseline biopsies were compared to those in subsequent core biopsies of
the same patients, and paired baseline biopsies obtained from the same
donors were also compared. To obtain moderate reproducibility of the
estimate of GS in paired baseline allograft biopsies or baseline biopsies
compared to subsequent core biopsies, at least 14 glomeruli were necessary.
For GS to predict outcome at least 25 glomeruli were needed.
AH was predictive of outcome irrespective
of sample size but was a less important predictor of outcome than GS in
cases were more than 25 glomeruli were available. IF was not predictive of
outcome.
Comment: The most significant finding of the study is that
much larger samples were
required than assumed for GS to be predictive of outcome. I suspect that
this need for a relatively generous sample is applicable more generally to
renal biopsies obtained from native kidneys. This is a pressing issue
because of the temptation to use thin gauge needles to minimize the risk of
postbiopsy bleeding. This can jeopardize the value of the biopsy: 1) many
of the glomeruli obtained with these instruments are partly amputated, 2)
even if multiple cores are submited separately for LM, IF, and EM it is a
matter of luck which will turn out to have medulla only; for example, in a
case where IF would have been critical for the diagnosis (e.g. IgA
nephropathy).
Concerns along that line were expressed at the most recent gathering of the
Renal Pathology Society and it was felt that guidelines ought to be issued.
Studies such as the present one should be of help in this regard.
(Samy S. Iskandar, MBBCh, PhD, Bowman Gray School of Medicine,
Winston-Salem, NC)
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Am Soc Nephrol
Proteinuria/Hematuria :
Renal biopsy techniques, tips, complications