Case 2 -
Lorraine C. Racusen
Johns Hopkins School of Medicine
Click on each slide thumbnail image for an enlarged view
The patient is an 18 year old male 11 months status post his second kidney transplant. He had
developed end-stage renal disease by the age of 12 due to chronic tubulo-interstitial disease of unknown
etiology. After about a year on peritoneal dialysis, the patient had received an initial living
unrelated transplant from an altruistic donor. The graft was a 3-antigen match; the patient was CMV and
EBV negative. The donor was CMV positive, and appropriate prophylaxis was given. A biopsy was performed
5 days post transplant for deterioration of renal function, and revealed focal thrombotic microangiopathy
(TMA), with very focal infarction. Because of concern about possible tacrolimus toxicity, he was
converted to Cellcept and prednisone, and eventually to cyclosporine. He subsequently had 2
biopsy-documented episodes of acute rejection, perhaps due to non-compliance, at 1 month and 13 months
post transplant. Both rejections were mild vascular type, Banff type 2A, with a significant
tubulo-interstitial component; immuno-staining for C4d was not being done at that time. He was treated
with OKT3 and ATGAM for these rejection episodes. Chronic allograft dysfunction and fibrosis evolved in
the graft, and he returned to dialysis. Due to recurrent fevers, rejection, and persistent requirement
for immunosuppression, he underwent graft nephrectomy approximately 2.7 years post-transplant.
Histological examination revealed acute and chronic rejection, with focal transmural arteritis and
extensive fibrosis in vessels and parenchyma; no viral inclusions were detected.
The second allograft was a 6 antigen match from a deceased donor. He had thymoglobulin induction
to avoid steroid use (he had avascular necrosis with involvement of right femoral head) and to avoid
calcineurin inhibitors. He had initial good urine output, but only slow decline in serum creatinine. He
developed fevers, migratory arthralgias, and decreased platelets and hemoglobin – testing for anti-donor
antibody was repeatedly negative. At 12 days post-transplant, a biopsy revealed acute rejection, Banff
type 2A, with diffuse capillary staining for C4d. He remained antibody negative, and he was treated with
OKT3, with return of brisk urine output and fall in creatinine to 1.3 mg%. He was discharged on
Rapamycin and Cellcept.
In the subsequent few months, he had a persistent lymphocele around the kidney, and required
placement of drains and a nephrostomy tube. A biopsy at 4 months revealed infiltrates suspicious for
rejection, with mild capillary margination and diffuse capillary staining for C4d (1-2+); antibody
screens remained negative. At 6.3 months post transplant, he presented with fever, abdominal pain,
increased drain output and graft tenderness. Open renal biopsy revealed acute rejection, Banff type 2B,
superimposed on chronic rejection. Neutrophil margination was noted in capillaries, with "fairly
diffuse" staining for C4d (1-2+). Approximately 9 months post transplant, he was hospitalized to place a
JP drain in the perinephric lymphocele; culture of fluid revealed VRE, treated with antibiotics. Renal
biopsy revealed acute rejection, Banff type 2A, with moderate evolving chronic changes and neutrophils in
glomerular and peritubular capillaries – R/O anti-donor antibody; screens for anti-donor antibody
remained negative. The patient had been chronically hypertensive on multiple medications. He was
switched from Rapamycin to cyclopsporine, due to marrow suppression. At 11 months post-transplant, he
developed a lung infiltrate and required ventilator support. His immunosuppression was stopped, and he
developed a clinical acute rejection. Allograft nephrectomy was performed.
Case 2 - Figure 1 - Low power view of section from allograft nephrectomy, showing 2 glomeruli, 1 ischemic and 1 with microangiopathic changes, including "bloodless" capillaries with flocculent material filling capillary loops and enmeshed erythrocytes with fragmentation. Background with interstitial edema, fibrosis and acute tubular injury.
Case 2 - Figure 2 - Higher power view of a "bloodless" glomerulus with swollen endothelial cells, and entrapped focally fragmented erythrocytes.
Case 2 - Figure 3 - Artery with marked intimal expansion, with myofibroblasts and a few entrapped mononuclear cells. Note endothelial activation but no arteritis.
Case 2 - Figure 4 - Artery with neo-intima formation and mononuclear inflammatory cells in middle layers of the thickened intima, findings of chronic rejection.
Case 2 - Figure 5 - Area of medullary hemorrhage and capillary congestion.
Case 2 - Figure 6 - Cells marginating in peritubular capillaries, including neutrophils and mononuclear cells. Note focal capillary endothelial activation.
Case 2 - Figure 7 - Isometric vacuolization in tubular cells, with apical blebbing. Some marginating cells in peritubular capillaries.
Case 2 - Figure 8 - Small vessel angiopathic changes, with thrombus and entrapped erythrocytes in vessel walls. Reactive and regenerative tubular cell changes.
Case 2 - Figure 9 - Focal peritubular capillary staining for C4d (1-2+) involving about 15% of capillaries overall.
The major finding in this kidney, in addition to chronic rejection and acute tubular injury, is
thrombotic microangiopathy. There are numerous "bloodless" glomeruli filled with flocculent material in
capillaries, with some severe capillary congestion and focal fragmentation of erythrocytes, and focal
thrombosis and mural injury with extravasation of erythrocytes in arterioles. Focal peritubular
capillary congestion and margination of inflammatory cells, including neutrophils, is noted. In
addition, there is a small infarct present on at least some of the sections. Finally, focal isometric
vacuolization can be identified in tubular epithelial cells. Arteries have focally severe fibrointimal
thickening, with mild edema and lymphocytes present deeper in the intima is some arteries, consistent
with chronic rejection. Immunostaining for C4d reveals trace-1+ staining in about 15-20% of peritubular
Possible causes of thrombotic microangiopathy (TMA) in the renal allograft include a variety of
processes. In the setting of the renal allograft, the most likely causes include:
The morphology of these entities is similar, not surprising since they all
result from endothelial injury, tipping the normal balance between thrombotic and anti-thrombotic factors
in the microvasculature toward thrombosis. Platelet activation and capillary injury can be demonstrated
in a variety of processes in the renal allograft . Vascular changes in malignant
hyptertension/scleroderma tend to be a bit different, with more arterial involvement and more fibrinoid
necrosis of vessel walls, features not seen in this case. Therefore, while the patient did have
persistent hypertension which could have contributed to endothelial injury, this is probably not the
primary insult, and the discussion will focus on the other entities.
- recurrent (or de
novo) hemolytic uremic syndrome/TTP;
- drug toxicity, including especially calcineurin inhibitors;
- anti-phospholipid antibody syndrome/autoimmune disease; and
In a recent analysis of incidence, time to event and risk factors for TMA in the allograft, the
USRDS data base was utilized to identify a historical cohort of recipients from January 1, 1998 to July
31, 2000, followed until December 31, 2000. Among those with end-stage renal disease due to HUS, 29.2%
had post-transplant TMA versus 0.8% incidence in other patients. Risk was highest in the first 3 months
post-transplant, but occurred later as well. Risk factors for de novo TMA included younger recipient
age, older donor age, female recipient and initial use of sirolimus. Patient survival rate after TMA was
approximately 50% at 3 years . Occasional cases of infection temporally related to de novo
post-transplant TMA have been reported, including CMV  and hepatitic C .
Certain forms of HUS recur more frequently post-transplant. In a recent review of the
literature, among 118 children transplanted after post-diarrheal HUS due to toxin-induced endothelial
injury, only 0.8% had recurrence. In contrast, of 63 children with diarrhea-negative HUS of unknown
mechanism, 21% had recurrence post-transplant. Of those with known underlying mechanisms of HUS,
recurrence and graft loss were highest in those with factor H deficiency, and low serum C3. The only
patient with constitutional deficiency of von Willebrand factor-cleaving protease, an underlying
mechanism of thrombotic thrombocytopenic purpura (TTP), had recurrence and graft loss . Another
recent study in pediatric patients also documented no recurrence and excellent outcome in 66 patients
with ESRD due to Shiga-toxin-induced HUS . Autosomal recessive and dominant forms of HUS have high
recurrence rates. Progress in the understanding of the mechanisms and genetics of diarrhea-negative HUS
are needed to more accurately predict recurrence rate and therapeutic approaches in this cohort.
Calcineurin inhibitors (CNIs) not uncommonly produce some diminution of GFR. Even therapeutic
doses of CNIs can activate endothelial cells, causing release of vasoactive factors balanced toward
vasoconstriction, such as endothelin and thromboxane, resulting in some "functional" reduction of GFR,
without morphological renal injury and rapidly reversible on discontinuation of or reduction in dosage of
the drug. At high doses and/or in sensitive individuals, more severe endothelial injury with release of
Von Willebrand factor multimers and platelet activating factor and features of hemolytic uremic syndrome
. Incidence of TMA has been reported to affect 1-14% of renal transplant recipients
administered CNI-based immunosuppression . Initially reported with cyclosporine, especially when used
in high doses and peaking again with introduction of the micro-emulsion formulation
complication has also been reported with therapy with tacrolimus (Prograf)
. It is sometimes
possible to reduce or discontinue one agent and re-introduce the same or alternative CNI at a later time
, though this is not without risk . The availability of other agents makes it possible, as
in this case, to avoid CNI use completely in many patients. Arterioles are a primary target, with
endothelial injury and/or ischemia in glomeruli. There is often isometric
vacuolization in tubular epithelial cells, a fairly reliable sign of exposure to high-dose calcineurin
inhibitors. CNI are generally used with caution in patients at risk for TMA recurrence in the allograft.
TMA has also been reported in patients being treated with other immunosuppressive agents,
. Potentiation of CsA-induced TMA has been reported with contemporaneous or
contiguous CNI and sirolimus use, perhaps due to increased intrarenal CsA levels in this setting
. A few cases of TMA in patients treated with sirolimus without CNI or OKT3 have also been
reported (e.g. 20)
Small vessel thrombosis and necrosis are also among the morphological correlates of
antibody-mediated/severe vascular rejection in the allograft
. In these cases, endothelial
injury apparently results from engagement of anti-donor antibody with antigens expressed on endothelial
cells, including HLA antigens (class I and II), AB antigens, and occasionally other endothelial antigens,
causing complement engagement and activation, with triggering of the complement cascade, recruitment of
inflammatory cells, and damage to endothelium and vessel wall if severe. Morphological features in some
cases include fibrin thrombi in glomeruli or vessels, or thromboses in glomeruli or arteries. Other more
common signs of antibody-mediated rejection, including margination in capillaries of neutrophils and
mononuclear cells/monocytes, arteritis, and immunostaining for C4d in a linear along peritubular
capillaries, provide morphological clues that AMR is present in the allograft . In the absence of
these features and/or demonstration of anti-donor antibody, other causes of endothelial injury should be
Anti-phospholipid antibody syndrome can recur post-transplant ,
sometimes in the setting of systemic lupus erythrematosus, resulting in increase in increased risk of
graft thrombosis . Morphology is very similar to other forms of TMA, and diagnosis is made by
demonstration of the antibody in the patient's serum. Renal TMA has been reported in HCV+ patients with
anti-cardiolipin antibody post-transplant .
Clinical presentation in patients with post-transplant TMA typically includes acute renal
dysfunction, often with hematological findings as well. In a recent series, 12/21 affected recipients
had "systemic" TMA with hemolysis and thrombocytopenia, whilc 8 patients had TMA apparently localized to
the allograft. The former cohort had more severe dysfunction and higher rate of graft loss .
Withdrawl or treatment of precipitating factors is the most effective therapeutic approach. Sirolimus
has been proposed as a CNI-sparing alternative in patients with drug-induced HUS, though potentiation of
CNI toxicity has occasionally been reported . Plasmapheresis/plasma exchange has been used to
attempt to limit the process. While general efficacy has not been established , some series report
good outcomes using these strategies  . Outcome is variable, depending on the underlying cause and
severity; as noted above, outcome in recurrent forms is generally poor.
In the current case, the native kidney disease was documented by biopsy; there was no evidence of
thrombotic microangiopathy in the native kidney, so that recurrence is not an issue in this case. There
were biopsy findings suggestive of CNI toxicity at 5 days in a first allograft, with no evidence of
rejeciton; calcineurin inhibitors were discontinued following that early biopsy, and not re-introduced
while that allograft was in place. CNI were also avoided in the second allograft, until weeks prior to
allograft nephrectomy. Recurrent rejection episodes (Banff type 2A) in the first allograft were ascribed
to non-compliance. In the second allograft, there were documented acute rejection episodes, Banff type
2a, with persistent morphological features suggestive of AMR and positive immunostaining for C4d without
any anti-donor HLA antibody ever demonstrated during the patient's course. This, of course, does not
rule out anti-donor antibody not detectable by routine screening methods. There are a number of
potential explanations for failure to demonstrate anti-donor antibody during AMR. One is that methods of
detection being used are not sensitive enough – this is generally not a problem with modern detection
methods, but occasionally is relevant in deceased donor transplants, since there may be time only for
cytotoxic cross-match and not for flow cross-matching pre-transplant, so that pre-existing low levels of
anti-donor antibody may be missed. Another possibility is that the antibody is non-HLA; more
sophisticated screening against a panel of endothelial antigens is possible, but was not performed in
this case. In addition, it is possible that antibodies were present episodically and/or at very low
levels, and were adsorbed to the graft; the clinicians were encouraged to re-screen the patient's serum
post-nephrectomy, in hopes of capturing an antibody peak on removal of the allograft. Only focal fairly
weak staining for C4d was present in peritubular capillaries at nephrectomy. There was no evidence of
anti-phospholipid antibody post-nephrectomy.
The final pathology in this nephrectomy specimen is most consistent with HUS, probably induced by
re-exposure to CNI in the weeks prior to nephrectomy, superimposed on a background of chronic rejection.
- Meehan SM, Limsrichamrern S, Manaligod JR, Junsanto T, Josephson MA, et al. Platelets and capillary injury in acute humoral rejection of renal allografts. Hum Pathol 34:533, 2003.
- Reynolds JC, Agodoa LY, Yuan CM, Abbott KC, Thrombotic microangiopathy after renal transplantation in the United States. Am J Kindey Dis 42:1058, 2003.
- Waiser J, Budde K, Rudolph B, Ortner MA, Neumayer HH. De novo hemolytic uremic syndrome postrenal transplant after cytomegalovirus infection. Am J Kidney Dis 34:556, 2003.
- Morales JM. Hepatitis C virus infection and renal disease after renal transplantation. Transplant Proc 36:760, 2004.
- Loirat C, Niaudet P. The risk of recurrence of hemolytic uremic syndrome after renal transplantation in children. Pediatr Nephrol 18:1095, 2003
- Ferraris JR, Ramirez JA, Ruiz S, Caletti MG, Vallejo G, et al. Shiga toxin-associated hemolytic uremic syndrome: absence of recurrence after renal transplantation. Pediatr Nephrol 17:809, 2002
- Pisoni R, Ruggenenti P, Remuzzi G. Drug-induced thrombotic microangiopathy: incidence, prevention, and management. Drug Saf 24:491, 2001
- Grupp C, Schmidt F, Braun F, Lorf T, Burckhardt R, Muller R. Haemolytic uraemic syndrome (HUS) during treatment with cyclosporin A after renal transplantation- is tacrolimus the answer? Nephrol Dial Transplant 13:1629, 1998.
- Schwimmer J, Nadasdy TA, Spitalnik PF, Kaplan KL, Zand MS. De novo thrombotic microangiopathy in renal transplant recipients: a comparison of hemolytic uremic syndrome with localized renal thrombotic microangiopathy. Am J Kidney Dis 41:471, 2003
- Shulman H, Striker G, Deeg RI, Kennedy M, Storb R, Thomas ED. Nephrotoxicity of cyclosporine A after allogeneic bone marrow transplantation: Glomerular thromboses and tubular injury. N Eng J Med 305:1392, 1981.
- Zarafian A, Meleg-Smith S, O'Donovan R, Tesi RJ, Batuman V. Cyclosporine-associated thrombotic microangiopathy in renal allografts. Kidney Int 55:2457, 1999.
- Wiener Y, Nakhleh RE, Lee MW, Escobar FS, Venkat KK, et al. Prognostic factors and early resumption of cyclosporine A in renal allograft recipients with thrombotic microangiopathy and hemolytic uremic syndrome. Clin Transplant 11:157, 1997.
- Randhawa PS, Shapiro R, Jordan ML, Starzl TE, Demetris AJ. The histopathological changes associated with allograft rejection and drug toxicity in renal transplant recipients maintained on FK506. Am J Surg Pathol 17:60, 1993.
- Mihatsch MJ, Kyo M, Morozumi K, YamaguchiY, Nickeleit V, Ryffel B. the side effects of cyclosporine-A and tacrolimus. Clin Nephrol 49:356, 1998.
- Burke GW, Ciancio G, Cirocco R, Markou M, Olson L, et al. Microangiopathy in kidney and simultaneous pancreas/kidney recipients treated with tacrolimus: evidence of endothelin and cytokine involvement. Transplantation 68:1336, 1999.
- Pham PT, Peng A, Wilkinson AH, Gritsch HA, Lassman C, et al. Cyclosporine and tacrolimus-associated thrombotic microangiopathy. Am J Kidney Dis 36:844, 2000.
- Abramowicz D, Pradier O, Marchant A, Florquin S, De Pauw L, et al. Induction of thromboses within renal grafts by high-dose prophylactic OKT3. Lancet 339:777, 1992.
- Robson M, Cote I, Abbs I, Koffman G, Goldsmith D. Thrombotic micro-angiopathy with sirolimus-based immunosuppression: potentiation of calcineurin-inhibitor-induced endothelial damage? Am J Transplant 3:324, 2003.
- Fortin MC, Raymond MA, Madore F, Fugere JA, Paquet M, et al. Increased risk of thrombotic microangiopathy in patients receiving a cyclosporine-sirolimus combination. Am J Transplant 4:946, 2004.
- Barone GW, Gurley BJ, Abul-Ezz SR, Gokden N. Sirolimus-induced thrombotic microangiopathy in a renal transplant recipient. Am J Kidney Dis 42:202, 2003.
- Trpkov K, Campbell P, Pazderka F, Cockfield S, Solez K, Halloran PF. Pathologic features of acute renal allograft rejection associated with donor-specific antibody; Analysis using the Banff grading schema. Transplantation 61:1586, 1996.
- Mauiyyedi S, Crespo M, Collins AB, Schneeberger EE, Pascual MA, et al. Acute humoral rejection in kidney transplantation: II. Morphology, immunopathology, and pathologic classification. J Am Soc Nephrol 13:779, 2002.
- Racusen L, Colvin RB, Solez K, et al, Antibody-mediated rejection criteria- an addition to the Banff 97 classification of renal allograft rejection. Am J Transplant 3:708, 2003.
- Mondragon-Ramirez G, Bochicchio T, Garcia-Torres R, Amigo MC, Martinez-Lavin M, et al. Recurrent renal thrombotic angiopathy after kidney transplantation in two patients with primary antiphospholipid syndrome. Clin Transplant 8:93: 1994.
- Irish A. Hypercoagulability in renal transplant recipients. Identifying patients at risk of renal allograft thrombosis and evaluating strategies for prevention. Am J Cardiovasc Drugs 4:139, 2004.
- Chiurchiu C, Ruggenenti P, Remuzzi G. Thrombotic microangiopathy in renal transplantation. Ann Transplant 7:28, 2002.
- Karthikeyan V, Parasuraman R. Shah V, Vera E, Venkat KK. Outcome of plasma exchange therapy in thrombotic microangiopathy after renal transplantation. Am J Transplant 3:1289, 2003.