Posttransplant tubulointerstitial nephritis: clinicopathological correlation.

As a cause of graft dysfunction, tubulointerstitial nephritis (TIN) seems to be the third most common pathology after rejection and cyclosporine nephrotoxicity. Among 540 needle biopsies obtained from 280 renal transplant patients between 1996 and 1999, acute TIN was detected in 23 patients (8%). The cause of acute TIN was secondary to bacterial infection in 17 patients and secondary to cytomegalovirus (CMV) infection in three patients. The remaining three cases showed granulomatous pyelonephritis due to Mycobacterium tuberculosis (n = 2) and Candida albicans (n = 1). During follow-up, 13 of 23 patients (56.5%) showed at least one acute rejection episode. The average number of urinary tract infection (UTI) episodes in the 23 patients was 1.4 +/- 07. We observed that the number of UTI episodes showed a significant association with the development of chronic allograft nephropathy (P = .03) and graft loss (P < .01). Twelve patients (52.2%) lost their grafts during 5 years posttransplantation. Only 6 of 17 patients with bacterial TIN lost their graft at a mean time of 52.5 +/- 14 months. But all patients with CMV TIN or granulomatous TIN lost their grafts at a mean time of 31 +/- 3.1 months and 39 +/- 3 months, respectively (P < .05). In conclusion, these results support the pathological role of tubulointerstitial nephritis as a pathway of graft rejection or renal allograft deterioration among recipients after transplantation.