[1616] Histopathological Response Patterns Following Treatment of Acute Renal Allograft Rejection

Mukul K Divatia, Sadhna Dhingra, Samir Patel, Jennifer Devos, Luan D Truong, Roberto Barrios, Richard J Knight, A Osama Gaber, Lillian Gaber. Methodist Hospital, Houston, TX

Background: Biopsy evaluation plays a key role in the diagnosis and grading of acute rejection and chronic changes. To date there are few descriptions of the histological outcomes of anti-rejection therapy. This study aimed to evaluate and compare post-rejection treatment biopsies with index biopsies to assess treatment response patterns.
Design: A retrospective review of 713 transplant biopsies from 2009-11 yielded 30 cases of acute rejection with biopsies performed to evaluate the response to therapy. Biopsies were obtained within 15-223 days (mean 54.6) after an index rejection biopsy. Banff 2007 criteria were used to classify acute cell mediated rejection (ACMR) and/or acute antibody mediated rejection (AAMR). The post treatment histological response was graded as: 1-complete resolution; 2-near complete if ACMR downgraded to borderline/ C4d staining reduced to ≤ 10 % of peritubular capillaries (PTC) in AAMR; 3-partial: ACMR downgraded by at least one grade/ C4d staining reduced by 50%; 4.-persistent without improvement. Features of new onset chronic changes including interstitial fibrosis and tubular atrophy (IFTA) and other chronic changes in tubules, interstitium, vessels and glomeruli were recorded.
Results: The cases were grouped based on type of rejection in the index biopsy into AAMR, AACMR, and Mixed AAMR/ACMR. The histological resolution responses are shown in Table 1.

Histological responseAAMR (n=4)ACMR (n=12)Combine AAMR/ACMR (n=14)
   AAMR ChangesACMR Changes
1 Complete resolution50%66.8%14.3%64.3%
2 Near complete resolution25%16.6%42.8%7.1%
3 Partial resolution25%16.6%14.3%14.3%
4 Persistent rejection0%0%28.6%14.3%
New onset IFTA25%33.3%50%
New onset glomerulopathy0%0%7.1%
New onset vasculopathy0%0%28.6%

Six of 16 (37.5%) cases with residual inflammation in post treatment biopsies showed higher grade of tubulitis as compared to interstitial inflammation. Combined AAMR and ACMR cases showed higher grades of new onset IFTA, glomerulopathy and vasculopathy.
Conclusions: Our results in AAMR and ACMR show that complete histological resolution was achieved in only 50-67 % of cases and there was new onset of IFTA in one third of the biopsies. Combined AAMR/ACMR rejections had lower rates of complete resolution of the AAMR changes. Persistent rejection and the development of transplant glomerulopathy and vasculopathy were only observed in the combined AAMR/ACMR rejections.
Category: Kidney (does not include tumors)

Monday, March 4, 2013 1:00 PM

Poster Session II # 221, Monday Afternoon


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