Fine-needle aspiration biopsy: a reproducibility study and a correlation with the tru-cut biopsy in the evaluation of renal allotransplants.

Forty patients receiving a living related donor kidney transplant in the last 12 months were subjected to evaluation by Fine Needle Aspiration Biopsies (FNABs) and Tru-cut biopsies. The reproducibility of the transplant aspiration cytology was tested by comparing 90 double FNABs (FNAB1 and FNAB2). Furthermore, the accuracy of FNABs was assessed by comparison with 30 kidney transplant Tru-cut biopsies obtained simultaneously. Statistical analysis showed no significant difference (P greater than 0.1) between FNAB1 and FNAB2 and both correlated positively with the Tru-cut biopsies. All the 25 acute rejection episodes documented by Tru-cut biopsies were positive in the simultaneously obtained FNABs. FNABs failed to diagnose histologically documented chronic rejection, humoral rejection, and a case of disseminated intravascular coagulation. In one case with deteriorating graft function, Tru-cut biopsy showed normal histology, yet transplant aspiration cytology showed cyclosporin nephrotoxicity. Sensitivity of transplant aspiration cytology was found to be 90.9% and specificity was 100%. We have concluded that FNAB when performed frequently, especially if double aspirates are obtained, is safe, sensitive and highly specific for diagnosis of renal transplant rejection. Humoral and chronic rejections are major limitations.