Thrombotic microangiopathy following allogeneic bone marrow transplantation is associated with intensive graft-versus-host disease prophylaxis

Histologic Features of Intestinal Thrombotic Microangiopathy in Pediatric and Young Adult Patients after Hematopoietic Stem Cell Transplantation

High-risk transplantation-associated thrombotic microangiopathy (TMA) can present with multisystem involvement and is associated with a poor outcome after hematopoietic stem cell transplantation (HSCT), with < 20% 1-year survival. TMA may involve the intestinal vasculature and can present with bleeding and ischemic colitis. There are no established pathologic criteria for the diagnosis of intestinal TMA (iTMA). The goal of our study was to identify histologic features of iTMA and describe associated clinical features. We evaluated endoscopic samples from 50 consecutive HSCT patients for 8 histopathologic signs of iTMA and compared findings in 3 clinical groups based on the presence or absence of systemic high-risk TMA (hrTMA) and the presence or absence of clinically staged intestinal graft-versus-host disease (iGVHD): TMA/iGVHD, no TMA/iGVHD, and no TMA/no iGVHD. Thirty percent of the study subjects had a clinical diagnosis of systemic hrTMA. On histology, loss of glands, intraluminal schistocytes, intraluminal fibrin, intraluminal microthrombi, endothelial cell separation, and total denudation of mucosa were significantly more common in the hrTMA group (P < .05). Intravascular thrombi were seen exclusively in patients with hrTMA. Mucosal hemorrhages and endothelial cell swelling were more common in hrTMA patients but this difference did not reach statistical significance. Patients with hrTMA were more likely to experience significant abdominal pain and gastrointestinal bleeding requiring multiple blood transfusions (P < .05). Our study shows that HSCT patients with systemic hrTMA can have significant bowel vascular injury that can be identified using defined histologic criteria. Recognition of these histologic signs in post-transplantation patients with significant gastrointestinal symptoms may guide clinical decisions.

Solid organ transplantation following end-organ failure in recipients of hematopoietic stem cell transplantation in children

Hematopoietic stem cell transplantation (HSCT) is an accepted treatment modality for various malignant and non-malignant disorders of the lympho-hematopoietic system. Patient survival rate has increased significantly with the use of this procedure. However, with the increase in disease-free patient survival rates, complications including various organ toxicities are also common. Kidney, liver, lung, heart, and skin are among those solid organs that are commonly affected and frequently lead to organ dysfunction and eventually end-organ disease. Conservative measures may or may not be successful in managing the organ failure in these patients. Solid organ transplantation has been shown to be promising in those patients who fail conservative management. This review will summarize the causes of solid organ (kidney, liver, and lung) dysfunction and the available data on transplantation of these solid organs in post-HSCT recipients.

Chronic kidney diseases in long-term survivors after allogeneic hematopoietic stem cell transplantation: monitoring and management guidelines

Chronic kidney disease (CKD) occurs commonly (prevalence of approximately 20% in a large series) after allogeneic hematopoietic stem cell transplantation (HSCT). There are three distinct clinical entities that occur after HSCT: thrombotic microangiopathy (TMA), nephrotic syndrome (NS), and idiopathic or graft-versus-host disease (GVHD)-related CKD. Acute renal function decline occurs in the majority of patients in the first months after transplantation. This acute kidney injury can persist and is a risk factor for the later development of CKD. However, the potentially independent role of GVHD, chronic inflammation, and chronic exposure to calcineurin inhibitors in the development and progression of CKD warrants further investigation. Careful monitoring of blood pressure, renal function, and proteinuria is mandatory in patients undergoing HSCT, especially older patients with pre-existent renal impairment. Renal function should be evaluated before HSCT and monitoring should occur at least every 6 to 12 months in these patients. Renal biopsies are indicated in patients with proteinuria and persistent or progressive rises in serum creatinine to determine etiology and prevent progression to end-stage renal disease (ESRD).

Diagnosis of intestinal graft-versus-host disease and thrombotic microangiopathy after allogeneic stem cell transplantation

Severe diarrhea is a serious complication after allogeneic hematopoietic stem cell transplantation (HSCT). Acute graft-versus-host disease (GVHD) has been one of the major causes of diarrhea after HSCT, which is triggered by donor-derived cytotoxic T-lymphocytes. On the other hand, intestinal thrombotic microangiopathy (TMA) sometimes coexists with acute GVHD, and intensified immunosuppression to treat acute GVHD could exacerbate intestinal TMA, presumably through the vascular endothelial cell damage. The differential diagnosis between intestinal TMA and acute GVHD of the gut has mainly relied on the pathological findings, as clinical diagnosis of intestinal TMA has not been established. Therefore, we aimed to assess the feasibility of our clinical diagnosis for the patients with diarrhea after HSCT. We made tentative clinical criteria for intestinal TMA and acute GVHD of the gut, based on the clinical manifestations, laboratory data and colonoscopic findings, and started treatment before pathological diagnosis were made. Subsequently, a pathologist retrospectively assessed the accuracy of clinical diagnosis in a blind manner. In this study, we enrolled 19 patients complicating watery diarrhea after HSCT, and diagnosed as having acute GVHD (n = 10), intestinal TMA (n = 3), or both (n = 6) according to our criteria. We demonstrated that our clinical diagnosis for intestinal TMA and acute GVHD of the gut was overall correct, in terms of the response to the therapy and the pathological diagnosis. The present study may provide a clue on making clinical diagnosis of patients with watery diarrhea after HSCT, which enables us to start a prompt therapy.

Thrombotic microangiopathies

Thrombotic microangiopathy results from thrombotic occlusion of the microvasculature leading to fragmentation of red blood cells, profound thrombocytopenia, and a microangiopathic hemolytic anemia with elevation of lactate dehydrogenase and negative direct Coomb's test. This constellation of clinical and laboratory findings is not due to one disease entity; rather, it represents a variety of underlying diagnoses. Among the major disease entities are TTP/HUS, which can be congenital or acquired, bacterial infections, medications, vascular or endothelial pathology like Kasabach-Merritt phenomenon, and stem cell transplantation. In this paper, we offer a review of some of the major causes of thrombotic microangiopathy.

Third-party mesenchymal stromal cell infusion is associated with a decrease in thrombotic microangiopathy symptoms observed post-hematopoietic stem cell transplantation

TA-TMA is a pathology that occurs after allogenic HSC transplantation with an incidence of 4-13%, and represents one of the most severe vascular damage related with this therapy. We report here the case of a nine-yr-old girl suffering from a severe refractory aplastic anemia who received an unrelated, 9/10 HLA-matched HSC. Soon after transplantation, the patient developed a graft-versus-host disease (GvHD), a TA-TMA, and renal insufficiency. These pathologies remained refractory to the various treatments undertaken and required several hospitalizations in the intensive care unit. On day 106 post-HSC transfusion, after several episodes of intensive care, the patient was infused with mismatched, third-party MSCs. Schizocyte levels rapidly decreased after MSC infusion, and two wk later, most biological parameters returned to normal. Erythrocyte and thrombocyte transfusions were discontinued, and the patient remained stable for 10 wk. Thereafter, TA-TMA symptoms, viral reactivation, pleural and cardiac effusions reappeared and lead to the death of the patient. Our observations suggest that allogenic MSC infusion may decrease the symptoms of TA-TMA, but further investigation is required to determine how and when MSC should be infused to develop a long-lasting protective effect.

Transplantation-associated thrombotic microangiopathy after steroid pulse therapy for polyserositis related to graft-versus-host disease

Transplantation-associated thrombotic microangiopathy (TA-TMA) is a rare but devastating syndrome that occurs in allogeneic hematopoietic stem cell transplant recipients, and is associated with a variety of transplantation-related factors, including conditioning regimens, immunosuppressive agents, graft-versus-host disease (GVHD) and opportunistic infections. TA-TMA has an unfavorable prognosis and responds poorly to conventional treatment including plasma exchange (PE). We present a case of a 37-year-old man with membranous nephropathy (MN) and polyserositis caused by GVHD after hematopoietic stem cell transplantation. He developed TA-TMA after steroid pulse therapy for polyserositis. We treated the patient with PE and mycophenolate mofetil (MMF) after which the TA-TMA successfully improved and the MN underwent complete remission. The present case suggests that corticosteroids with severe GVHD might increase the risk of TA-TMA, and that PE in combination with MMF may be a valuable therapy to improve the prognosis.

Thrombotic microangiopathy in haematopoietic cell transplantation: an update

Allogeneic hematopoietic cell transplantation (HCT) represents a vital procedure for patients with various hematologic conditions. Despite advances in the field, HCT carries significant morbidity and mortality. A rare but potentially devastating complication is transplantation-associated thrombotic microangiopathy (TA-TMA). In contrast to idiopathic TTP, whose etiology is attributed to deficient activity of ADAMTS13, (a member of the A Disintegrin And Metalloprotease with Thrombospondin 1 repeats family of metalloproteases), patients with TA-TMA have > 5% ADAMTS13 activity. Pathophysiologic mechanisms associated with TA-TMA, include loss of endothelial cell integrity induced by intensive conditioning regimens, immunosuppressive therapy, irradiation, infections and graft-versus-host (GVHD) disease. The reported incidence of TA-TMA ranges from 0.5% to 75%, reflecting the difficulty of accurate diagnosis in these patients. Two different groups have proposed consensus definitions for TA-TMA, yet they fail to distinguish the primary syndrome from secondary causes such as infections or medication exposure. Despite treatment, mortality rate in TA-TMA ranges between 60% to 90%. The treatment strategies for TA-TMA remain challenging. Calcineurin inhibitors should be discontinued and replaced with alternative immunosuppressive agents. Daclizumab, a humanized monoclonal anti-CD25 antibody, has shown promising results in the treatment of TA-TMA. Rituximab or the addition of defibrotide, have been reported to induce remission in this patient population. In general, plasma exchange is not recommended.

Thrombotic microangiopathy in haematopoietic stem cell transplantation: diagnosis and treatment

Each year in the US, more than 10 000 patients benefit from allogeneic haematopoietic stem cell transplantation (HSCT), a modality that offers an excellent chance of eradicating malignancy but confers a higher risk of treatment-related mortality. An uncommon but devastating consequence of HSCT is transplantation-associated thrombotic microangiopathy (TA-TMA). The incidence of TA-TMA ranges from 0.5% to 76%, with a mortality rate of 60-90% despite treatment. Although there appears to be a consistent treatment approach to idiopathic thrombotic thrombocytopenic purpura (TTP) using plasma exchange, corticosteroids and rituximab, the treatment strategies for TA-TMA are perplexing, in part, because the literature regarding this complex condition does not provide true consensus for incidence, aetiology, diagnostic criteria, classification and optimal therapy. The classic definition of idiopathic TTP includes schistocytes on the peripheral blood smear, thrombocytopenia and increased serum lactate dehydrogenase. Classic idiopathic TTP has been attributed to deficient activity of the metalloproteinase responsible for cleaving ultra-large von Willebrand factor multimers. This protease is a member of the 'a disintegrin and metalloprotease with thrombospondin type 1 motif' family and is subsequently named ADAMTS-13. Severely deficient ADAMTS-13 activity (<5% of normal) is associated with idiopathic TTP in 33-100% of patients. In constrast to the pathophysiology of idiopathic TTP, patients with TA-TMA have >5% ADAMTS-13 serum activity. These data may explain why plasma exchange, a standard treatment modality for idiopathic TTP that restores ADAMTS-13 activity, is not effective in TA-TMA. TA-TMA has a multifactorial aetiology of endothelial damage induced by intensive conditioning therapy, irradiation, immunosuppressants, infection and graft-versus-host disease. Treatment consists of substituting calcineurin inhibitors with an alternative immunosuppressive agent that possesses another mode of action. One candidate may be daclizumab, especially in those with mild to moderate TMA. Rituximab therapy or the addition of defibrotide may also be beneficial. In general, plasma exchange is not recommended.

Renal thrombotic microangiopathy after hematopoietic cell transplant: role of GVHD in pathogenesis

BACKGROUND AND OBJECTIVES

Thrombotic microangiopathy (TMA) is a known complication of hematopoietic cell transplantation (HCT). The etiology and diagnosis of TMA in this patient population is often difficult because thrombocytopenia, microangiopathic hemolytic anemia, and kidney injury occur frequently in HCT recipients, and are the result of a variety of insults.

DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS

The authors reviewed renal pathology and clinical data from HCT patients to determine the prevalence of TMA and to identify correlative factors for developing TMA in the kidney. Kidney tissue was evaluated from 314 consecutive autopsies on patients who died after their first HCT (received between 1992 and 1999). Renal pathology was classified into three groups: (1) no renal thrombus (65%), (2) TMA (20%), and (3) isolated thrombosis (15%). Logistic regression models estimated the associations between each histologic category and clinical parameters: donor and recipient gender, patient age, human leukocyte antigen (HLA) matching of the donor and recipient, total body irradiation (TBI), acute graft versus host disease (GVHD), acute kidney injury, medications, and viral infections.

RESULTS

In a multivariate analysis, TMA correlated with acute GVHD grades II to IV, followed by female recipient/male donor, TBI > 1200 cGy, and adenovirus infection. Grades II to IV acute GVHD and female gender were associated with isolated renal thrombus.

CONCLUSIONS

TMA in HCT recipients is associated with acute GVHD grades II to IV, recipient/donor mismatch, TBI > 1200 cGy, and adenovirus infection.

Management of stroke in cancer

Cerebrovascular disorders, including brain infarction, brain hemorrhage, and cerebral venous thrombosis, can occur as an early sign of cancer, but typically occur late in the clinical course. These disorders are due to a variety of pathogenic mechanisms, including coagulation disorders associated with the cancer, invasion or compression of vessels from tumor in or adjacent to the brain, and the adverse effects of cancer therapy. The appropriate therapy for these cerebrovascular disorders is empiric in most instances, because as yet there are no prospective treatment trials for them. A review of the existing literature reveals that improvement in patient quality of life and prevention of further cerebrovascular events can be obtained in some clinical situations.

Diagnosis and treatment of transplantation-associated thrombotic microangiopathy: real progress or are we still waiting?

Transplantation-associated thrombotic microangiopathy (TA-TMA) is an infrequent but devastating syndrome that occurs in allogeneic hematopoietic stem cell transplant recipients, and is associated with a variety of transplantation-related factors, including conditioning regimens, immunosuppressive agents, GVHD and opportunistic infections. Progress in managing this condition has been hampered by lack of a consensus definition and poor understanding of the pathophysiology of the disorder. Two different groups recently have proposed consensus definitions, yet they fail to distinguish the primary syndrome from the secondary causes, such as a variety of infections, medication exposure or other conditions. Increasing evidence suggests that TA-TMA is a multifactorial disorder that is distinct from thrombotic thrombocytopenic purpura (TTP), and likely represents the final common pathway of a number of endothelial cell insults. TA-TMA responds poorly to conventional treatment for TTP, including plasma exchange, but newer agents, including daclizumab and defibrotide show promise. In addition, other agents known to modify endothelial responses to injury, including statins, prostacyclin analogues, endothelin-receptor antagonists and free radical scavengers, may lead to improved outcomes for patients affected by this disorder.

Transplant-associated microangiopathy in patients receiving tacrolimus following allogeneic stem cell transplantation: risk factors and response to treatment

Transplant-associated microangiopathy (TAM) is a life-threatening complication after allogeneic HSCT, particularly with the use of calcineurin inhibitors as post-transplantation immunosuppressive therapy. We report our experience with TAM after HSCT with tacrolimus-based GVHD prophylaxis in a single-center study. Sixty-six of 1219 transplant recipients developed TAM with a cumulative incidence of 5.9%. Risk factors for TAM were female gender, lymphoid malignancy, receipt of a matched unrelated donor, and grade II-IV aGVHD. Most patients had infection and/or active GVHD at the diagnosis of TAM (82%). In the absence of renal dysfunction or encephalopathy, tacrolimus was generally continued, maintaining blood levels within the lower therapeutic range. Sixty-three patients were treated with plasma exchange. The cumulative incidence of response of TAM was 60%. Only 1 patient had a response of TAM without resolution of concomitant infections or GVHD. Six-month survivals were 0% and 50% for TAM nonresponders and responders, respectively. In conclusion, TAM is a common, life-threatening complication of allogeneic hematopoietic transplantation using tacrolimus prophylaxis. Control of TAM generally requires response of associated infections and GVHD. TMA response may occur despite continuation of tacrolimus treatment.

Intestinal thrombotic microangiopathy induced by FK506 in rats

Thrombotic microangiopathy (TMA) is one of the severe complications after stem cell transplantation (SCT) and is associated with graft-versus-host disease (GVHD) prophylaxis including FK506. In this study, we experimented on rats using FK506 to demonstrate the occurrence of intestinal TMA. FK506 was administrated into Wistar/ST rats intraperitoneally for 7 days. Rats were examined histopathologically after FK506 injection using light and electron microscopy and immunohistochemistry. FK506 concentrations in whole blood were measured by enzyme immunoassay. In the acute phase, hemorrhagic lesions with multifocal erosions and crypt loss were found in the small intestines of all treated rats. Capillary vessels were dilated, and a few platelet thrombi were found. Electron microscopy demonstrated degenerative swelling of endothelial cells and platelet aggregates adhering to the vessel walls. In the later phase, epithelial regenerative failure, characterized by crypt ghosts, was found in the affected mucosa. Apoptotic epithelial cells were increased in number. The extent of intestinal injury was proportional to the whole blood levels of FK506. The intestinal lesions in rats were consistent with TMA and induced by the injection of FK506 alone. Apoptotic enteropathy was also observed and similar to intestinal GVHD. In this study, we established an intestinal TMA model induced by immunosuppressant (Tacrolimus) only without irradiation.

Epstein-Barr virus-associated enteritis with multiple ulcers after stem cell transplantation: first histologically confirmed case

The present case involves unique enteritis forming multiple ulcers associated with Epstein-Barr virus (EBV). A 57-year-old man had undergone a reduced intensity allogeneic stem cell transplantation for a relapse of multiple myeloma following sequential autologous peripheral blood stem cell transplantation. The ileum, resected for massive melena, showed multiple irregular ulcers with occasional cobblestone-like appearance. There was inflammation including numerous plasma cells in the ulcer bases and surrounding areas, where many EBV-infected plasma cells were detected by double staining with EBV-encoded small RNA-1 (EBER-1) in situ hybridization and CD79a, while EBV-infected epithelial cells were not noted. The number of EBER-1-positive cells in the ileum (mucosa, 1451 cells/mm(2); submucosa, 465 cells/mm(2)) was much larger than in control samples (malignant lymphoma or leukemia after allogeneic stem cell transplantation, n = 4, range 0-113 cells/mm(2); malignant lymphoma after chemotherapy, n = 14, range 0-0.89 cells/mm(2); colon cancer, n = 12, range 0-3.5 cells/mm(2)). In the mucosa near the ulcers, EBER-1-positive cells often surrounded and involved the glandular epithelium, forming lymphoepithelial-like lesions. The histological findings differ from post-transplant lymphoproliferative disorders or intestinal thrombotic microangiopathy, and this is the first case of EBV-associated enteritis with ulcers characterized by numerous plasma cells and lymphoepithelial-like lesions after stem cell transplantation.

Risk Factors and Severe Outcome in Thrombotic Microangiopathy After Allogeneic Hematopoietic Stem Cell Transplantation

BACKGROUND

Thrombotic microangiopathy (TMA) has been described as severe complication after hematopoietic stem cell transplantation (HSCT). The principal aim of this study was to focus the incidence and the outcome of TMA in the era of more complex HSCTs.

METHODS

We analyzed the role of some predicting factors for the incidence and the outcome of TMA after HSCT. We enrolled 539 consecutive patients (307 males, median age 31 years) undergoing HSCT from match or mismatch human leukocyte antigen family donor (314) or match/mismatch unrelated (195) and haploidentical donor (30) for malignant or nonmalignant diseases. TMA diagnosis was performed by homogeneous clinical and laboratory criteria.

RESULTS

Sixty-four of 539 patients presented TMA (11,87%) and the five-year cumulative incidence of TMA was 14% (HR=0.13). Fifty nine of 64 patients were affected by malignant and 5/64 by non-malignant diseases. On multivariate analysis, TMA occurrence was influenced by graft versus host disease >grade II (P=0.0001), donor type (P=0.029), gender (P=0.0233), total body irradiation based conditioning regimen (P=0.0041). Three factors for TMA outcome proved to be statistically significant by multivariate analysis: age (P=0.009), donor type (P=0.0187) and TMA index (P=0.029). The TMA mortality rate was 50%. The outcome was influenced by defibrotide (P=0.02 in univariate analysis).

CONCLUSIONS

The study underlines the possibility of finding out which patients are more prone to developing post-HSCT TMA, and identifies which risk factors are more frequently associated with a dismal outcome after TMA.

Risk factor analysis for thrombotic microangiopathy after reduced-intensity or myeloablative allogeneic hematopoietic stem cell transplantation

Thrombotic microangiopathy (TMA) impairs long-term survival after allogeneic hematopoietic stem cell transplantation (HSCT). As the allogeneic HSCT procedure has developed, addressing risk factors for TMA has become more complicated. The aim of this study was to investigate the impact of transplant-associated factors on TMA incidence in patients who have undergone HSCT in various settings. One hundred twenty-three consecutive allogeneic HSCT patients with hematologic diseases receiving myeloablative and reduced-intensity conditioning were evaluated retrospectively. Of 123 patients, 22 (17.9%) developed TMA after HSCT. Multivariate analysis showed the significance of GVHD grade II-IV, and the use of FK506 and the use of high-dose busulfan (Bu) (16 mg/kg) persisted. The hazard ratios of the use of FK506, the use of high-dose Bu (16 mg/kg), and GVHD grade II-IV for TMA were 8.7 (95% CI 2.0-37), 5.7 (95% CI 1.5-21), and 3.4 (95% CI 1.3-9.1), respectively. In the present study, reduced-intensity conditioning did not have an advantage over myeloablative conditioning in decreasing the incidence of TMA after HSCT. Our results also showed that high-dose Bu (16 mg/kg) for the conditioning and FK506 for the prophylaxis of GVHD might contribute more significantly to TMA onset after HSCT than other agents.

Chronic kidney disease in long-term survivors of hematopoietic cell transplantation: epidemiology, pathogenesis, and treatment

High-dose myeloablative hematopoietic cell transplantation is becoming an increasingly common treatment modality for a variety of diseases. Patient survival may be limited by substantial treatment-related toxicities, including chronic kidney disease (CKD). Although the majority of CKD after transplantation is idiopathic, thrombotic microangiopathic syndromes and nephrotic syndrome have been described. Epidemiology, pathogenesis, and potential treatment options for the various clinical syndromes that are associated with CKD in hematopoietic cell transplantation patients is reviewed. As the indications for and the numbers of transplants that are performed worldwide increases, so will the burden of CKD. The nephrologists and oncologists will have to work together to identify patients who are at risk for CKD early to prevent its development and progression to end-stage kidney disease.

Variable incidence of cyclosporine and FK-506 neurotoxicity in hematopoeitic malignancies and marrow conditions after allogeneic bone marrow transplantation

INTRODUCTION

This study examines whether malignant disease under treatment influences the incidence of cyclosporine or FK-506 neurotoxicity after myeloablative conditioning and allogeneic bone marrow transplantation (allo-BMT).

METHODS

Review of 290 patients who received myeloablative conditioning prior to allo-BMT and cyclosporine/FK-506 identified 21 (7.2%) patients with neurotoxicity confirmed by computed tomography or magnetic resonance. Underlying malignancy necessitating allo-BMT included leukemias (67%), lymphoma (10%), myelodysplastic syndrome (10%), and multiple myeloma (MM). Frequency of neurotoxicity by disease was compared.

RESULTS

The highest incidence of neurotoxicity was present with MM (25%), whereas the lowest incidence was present with lymphoma (2.7%). Other diseases demonstrated intermediate incidence, including acute leukemias (10%), myelodysplastic syndrome (6.4%), and chronic myelogenous leukemia (4.9%).

CONCLUSION

Cyclosporine/FK-506 neurotoxicity varied according to the underlying malignancy. The variable susceptibility to the development of neurotoxicity in this population may depend on the interaction of host vasculature with disease specific factors. Understanding the cause of neurotoxicity could improve survival after allo-BMT.

Sirolimus and thrombotic microangiopathy after allogeneic hematopoietic stem cell transplantation

Thrombotic microangiopathy (TMA) may occur after allogeneic hematopoietic stem cell transplantation (HSCT) and is related in part to calcineurin inhibitor toxicity. We observed a higher-than-expected rate of TMA when calcineurin inhibitors were combined with sirolimus. To determine the incidence of and risk factors for TMA after HSCT, we performed a retrospective cohort analysis of myeloablative allogeneic HSCT recipients between 1997 and 2003. TMA diagnosis required the simultaneous occurrence of (1) creatinine increase >2 mg/dL or >50% above baseline, (2) schistocytosis, (3) increased lactate dehydrogenase, and (4) no evidence of disseminated intravascular coagulopathy. A total of 111 sirolimus-exposed subjects were compared with 216 nonexposed subjects after HSCT. TMA occurred in 10.8% of the sirolimus group and 4.2% in the nonsirolimus group (odds ratio, 2.79; P=.03). Sirolimus exposure was associated with TMA earlier than in nonsirolimus patients (25 versus 58 days; P=.04). Only the use of sirolimus (exact odds ratio, 3.49; P=.02) and grade II to IV acute graft-versus-host disease (exact odds ratio, 6.60; P=.0002) were associated with TMA in regression analyses. Treatment of TMA varied among affected individuals. Renal recovery was complete in 92% of sirolimus-treated patients. Overall survival after TMA diagnosis was better for sirolimus subjects than for nonsirolimus subjects (58.3% versus 11.1%; P=.02). Sirolimus seems to potentiate the effects of calcineurin inhibitors on TMA after HSCT. TMA associated with sirolimus seems reversible and has a favorable prognosis when compared with TMA associated with calcineurin inhibitors alone. A careful monitoring strategy for TMA should be used with a sirolimus-containing graft-versus-host disease prophylaxis regimen.

Transplant-associated microangiopathy (TAM) in recipients of allogeneic hematopoietic stem cell transplants

We studied occurrence, risk factors and outcome of patients with transplant-associated microangiopathy (TAM) after allogeneic stem cell transplantation (HSCT). A total of 221 consecutive patients were transplanted between 1995 and 2002. TAM is defined as evidence of hemolysis and schistocytes in the first 100 days. Outcomes analyzed included TAM and overall survival. Of 221 patients, 68 had TAM. The cumulative incidence was 31 (25-38)% at 100 days. Patients with TAM had higher LDH, higher bilirubin, higher creatinine and more often neurologic symptoms. TAM was not associated with stem cell source, cyclosporine levels and was not more frequent in recent years. In multivariate analysis, risk factors for TAM included donor type, age, gender, ABO-incompatibility and acute graft-versus-host disease (aGvHD). In patients with TAM, 1-year survival was lower than in patients without TAM (27 +/- 18% for TAM with high schistocyte counts; 53 +/- 15% for TAM with low schistocyte counts; vs 78 +/- 7% in patients without TAM; P<0.0001). TAM was independently associated with mortality adjusting for donor type, age and aGvHD occurrence and severity. TAM is frequent after HSCT and is associated with mortality even after adjustment for aGvHD grade. Risk factors of TAM are similar to aGvHD. TAM may represent endothelial damage driven by donor-host interactions.

Acute renal failure after myeloablative hematopoietic cell transplant: incidence and risk factors

BACKGROUND

Survival after myeloablative therapy followed by hematopoietic cell transplant (HCT) is limited by substantial treatment-related toxicities. Acute renal failure (ARF) develops in 25% to 50% of patients after HCT.

METHODS

One hundred forty-seven patients were followed prospectively from time of transplant. ARF was defined as a doubling of baseline serum creatinine at any time during the first 100 days post-transplant. We conducted a nested case-control study to identify precipitants of ARF. For each person who developed ARF, 2 controls were selected at random from patients who had not developed ARF as of that time. An exposure period was defined for each case as the 2 weeks prior to the day on which the matched case met the criteria for ARF. The risk of ARF in relation to demographic and anthropometric characteristics, and to types of treatment and comorbidity, was examined using univariable and multivariable conditional logistic regression models. Odds ratios for the associations with ARF were estimated, taking into account the matching.

RESULTS

Fifty-three patients (36%) developed ARF at a median of 33 days after transplant (range 1 to 97). Elevated risks were observed in patients who received liposomal amphotericin (OR 6.58; 95%CI 1.45-29.95) and conventional (OR 3.60; 95%CI 0.79-16.55), and in those patients with sinusoidal obstruction syndrome (SOS) (previously termed veno-occlusive disease) (OR 9.37; 95%CI 2.29-38.38). For every 0.1 mg/dL increase in baseline serum Cr, the risk of ARF decreased by 30%. Neither total body irradiation (TBI) dose, levels of metabolites of cyclophosphamide, sepsis, acute graft versus host disease (GVHD), nor cyclosporine (CSA) levels was associated with an increased risk of ARF.

CONCLUSION

The cumulative incidence of ARF after HCT remains high. Amphotericin use during the 2-week exposure period and presence of hepatic sinuosoidal injury increased the risk of ARF within the first 100 days after HCT. Higher levels of serum creatinine at baseline were associated with a lower risk of ARF.

In vitro effect of cyclosporin A, mitomycin C and prednisolone on cell kinetics in cultured human umbilical vein endothelial cells

INTRODUCTION

Vascular endothelial cell damage plays an important role in microvascular thrombogenesis. In vivo administration of cyclosporin A or mitomycin C sometimes results in thrombotic microangiopathy in patients.

MATERIALS AND METHODS

The effects of cyclosporin A, mitomycin C and/or prednisolone on the cell cycle in cultured human umbilical vein endothelial cells were investigated to evaluate drug-induced endothelial cell damage and the protective effect of prednisolone on endothelial cells against the damage by cyclosporin A or mitomycin C in vitro.

RESULTS

The addition of cyclosporin A to cultures caused proliferation arrest in the G1-phase in a dose-dependent manner, while mitomycin C inhibited DNA synthesis, which resulted in cell cycle arrest and inhibition of BrdUrd incorporation in the S-phase. The administration of prednisolone also caused cell cycle arrest in the G1 by itself, and protected the cells from the damage caused by mitomycin C. The inhibitory effects of cyclosporin A and prednisolone on the cell cycle were reversible, while mitomycin C was not. The highly phosphorylated retinoblastoma protein expressed in human umbilical vein endothelial cells decreased in the presence of mitomycin C. Soluble thrombomodulin levels in the culture supernatant were elevated by the addition of cyclosporin A.

CONCLUSION

These effects of the drugs may cause the cell cycle arrest and the prolonged repair of damaged endothelial cells in patients.

Thrombotic Microangiopathy after Allogeneic Blood and Marrow Transplantation Is Associated with Dose-Intensive Myeloablative Conditioning Regimens, Unrelated Donor, and Methylprednisolone T-Cell Depletion

BACKGROUND

Allogeneic blood and marrow transplantation (BMT)-associated thrombotic microangiopathy (TM) contributes to transplant-related morbidity and mortality. This report examines the incidence of and risk factors for allogeneic BMT-associated TM in two patient cohorts treated before and after changes in myeloablative conditioning regimen intensity (high vs. standard intensity).

METHODS

Cohort 1 includes 153 consecutive allogeneic BMT patients who underwent transplantation between April 1994 and October 1997 with an allogeneic BMT-associated TM crude incidence of 12%. Cohort 2 includes 75 consecutive allogeneic BMT patients who underwent transplantation from November 1997 to November 2000 with an allogeneic BMT-associated TM crude incidence of 1%.

RESULTS

In cohort 1, matched unrelated donor transplant and methylprednisolone (MP) T-cell depletion (TCD) of donor bone marrow were significantly associated with allogeneic BMT-associated TM by univariate analysis; therefore, a logistic model incorporating these effects was constructed to calculate the expected number of allogeneic BMT-associated TM cases in cohort 2. Seven cases would have been expected, but only one was observed (P = 0.003; bayesian predictive test). The multivariate analysis of both cohorts yielded MP-TCD (P<0.001), high-intensity myeloablative conditioning regimens used in cohort 1 (P = 0.02), and matched unrelated donor (P = 0.03) as significant predictors of time to allogeneic BMT-associated TM.

CONCLUSION

Avoidance of high-intensity conditioning regimens may decrease the incidence of allogeneic BMT-associated TM.

Successful Treatment of Tacrolimus (FK506)-Related Leukoencephalopathy with Cerebral Hemorrhage in a Patient Who Underwent Nonmyeloablative Stem Cell Transplantation

A 46-year-old woman with Hodgkin's disease who underwent nonmyeloablative allogeneic stem cell transplantation developed cortical blindness, seizures, and left hemiparesis on day 100 while receiving tacrolimus (FK506) and prednisone for the treatment of graft-versus-host disease (GVHD). Magnetic resonance imaging revealed multiple changes, mainly in the bilateral occipital lobes, suggesting FK506-related leukoencephalopathy. These abnormalities improved after discontinuation of FK506. However, 3 days after the episode, cerebral hemorrhage in the left occipital lobe with perforation to the left subdural space occurred. Although FK506-induced leukoencephalopathy with cerebral hemorrhage is considered the more severe form of such leukoencephalopathy, the patient's neurological symptoms almost completely resolved and radiographic findings improved after discontinuation of FK506, tapering of methylprednisolone, and initiation of mycophenolate mofetil. FK506-related leukoencephalopathy is a rare complication after allogeneic stem cell transplantation. Although the symptoms usually subside after discontinuation of FK506, therapeutic intervention in many cases may result in severe complications, including GVHD and vascular disease. We consider it important to use immunosuppressive agents without vascular endothelial toxicity for preventing the development of fatal GVHD after discontinuation of FK506.

Thrombotic microangiopathy after allogeneic stem cell transplantation in the era of reduced-intensity conditioning: The incidence is not reduced

Thrombotic microangiopathy (TMA) is one of the most severe complications of stem cell transplantation (SCT). Endothelial cell injury caused by the toxic effects of high-dose chemoradiotherapy is likely the primary event in pathogenesis. The incidence, clinical settings, and risk factors for TMA in the era of nonmyeloablative conditioning have not been well defined. The data on 147 consecutive SCTs in a single center were collected, and patients with TMA were identified. Patient characteristics, response to therapy, and outcome were recorded, and risk factors were determined. TMA occurred in 22 of 147 transplantations, with a projected incidence of 20% +/- 4%. TMA occurred in 3 clinical settings: classic multifactorial TMA, TMA associated with severe hepatic graft-versus-host disease (GVHD), and TMA associated with second SCT, with a projected incidence of 8% +/- 3%, 73% +/- 14%, and 70% +/- 16% of patients at risk, respectively. TMA occurred after 23% +/- 6% of nonmyeloablative and 16% +/- 5% of myeloablative conditioning regimens (not significant). Univariate analysis determined SCT from unrelated donors, SCT during advanced or active disease, second SCT within 6 months of a prior SCT, and acute GVHD as risk factors for TMA. The last 2 factors remained significant in a multivariate model. Thirty-two percent of patients responded to therapy. The peri-TMA mortality rate was 68% +/- 10%. Six patients had diffuse alveolar hemorrhage complicating TMA. SCT-associated TMA is a relatively common complication with unsatisfactory therapy and grim prognosis. Fludarabine-based nonmyeloablative conditioning does not confer a lesser risk for TMA. This observation may relate to the selective use of these regimens in elderly and heavily pretreated patients or to the lack of reduction of GVHD with these regimens, and fludarabine itself may be involved in causing endothelial damage. Further exploration of novel preventive and therapeutic measurements is required in high-risk settings.

Intestinal thrombotic microangiopathy after allogeneic bone marrow transplantation: a clinical imitator of acute enteric graft-versus-host disease

Thrombotic microangiopathy after bone marrow transplantation (post-BMT TMA) is a serious transplant-related complication. We identified 16 patients with TMA after allogeneic BMT who showed histopathological evidence of intestinal TMA in their gut specimens (six autopsies, 10 biopsies). In all, 14 patients had grade II-IV acute graft-versus-host disease (GVHD). The first seven patients were retrospectively diagnosed with TMA. Since six of them were diagnosed with progressive GVHD at that time because there was no awareness of the existence of intestinal TMA, they received more intensive treatment for GVHD, but all died between days +49 and +253. In contrast, the remaining nine patients were recently diagnosed with intestinal TMA on the basis of colonoscopic biopsies. For eight of these patients, the immunosuppressants were reduced, and the patients' intestinal symptoms improved gradually. Six of the nine patients were still alive 12 months after the diagnosis of TMA. Our findings suggest that the gut may be a site involved in post-BMT TMA, presenting as ischemic enterocolitis. Differentiating intestinal TMA from acute GVHD is important in patients suffering from severe and refractory diarrhea after BMT.

Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome following allogeneic HPC transplantation: a diagnostic dilemma

BACKGROUND

Thrombotic thrombocytopenic purpura-hemolytic uremic syndrome (TTP-HUS) has been described as a specific sequela of allogeneic HPC transplantation (HPCT). Nevertheless, because multiple transplant-related sequela can cause the characteristic clinical features of TTP-HUS, the diagnosis is difficult.

STUDY DESIGN AND METHODS

All English-language articles describing patients with TTP-HUS following HPCT were identified. Articles reporting five or more total patients, including at least one patient diagnosed with TTP-HUS following allogeneic HPCT, were reviewed. All articles describing autopsies of patients diagnosed with TTP-HUS following allogeneic HPCT were also reviewed.

RESULTS

Thirty-five articles reporting 5 or more total patients described 447 patients diagnosed with TTP-HUS following allogeneic HPCT. The frequency of diagnosis of TTP-HUS following allogeneic HPCT varied by 125-fold (0.5%-63.6%). Twenty-eight different sets of diagnostic criteria were described in the 35 articles; 25 articles included both RBC fragmentation and increased serum LDH. Many risk factors described as correlating with the diagnosis of TTP-HUS also predict greater risk for multiple transplant-related complications. Benefit of plasma exchange treatment could not be documented. Survival information was reported for 379 patients, 232 (61%) died, and reported mortality rates varied from 0 to 100 percent. Autopsies have been reported for 35 patients who were diagnosed with TTP-HUS following allogeneic HPCT; none had systemic thrombotic microangiopathy, the diagnostic abnormality of TTP-HUS; and infection (19 patients) was the most commonly reported cause of death.

CONCLUSIONS

The clinical features of TTP-HUS following allogeneic HPCT may be caused by common transplant-related complications; the benefit from plasma exchange treatment is uncertain.

Therapeutic plasma exchange in patients with grade 2-3 hematopoietic stem cell transplantation-associated thrombotic thrombocytopenic purpura: a ten-year experience

In the present retrospective study we report our 10-year experience with therapeutic plasma exchange (TPE) in 18 patients with grade 2-3 hematopoietic stem cell transplantation (HSCT)-associated thrombotic thrombocytopenic purpura (TTP). During TPE a mean total quantity of 26.5 +/- 15.1 L of plasma was exchanged. Five patients (27.7%) had a complete response eight patients (44.4%) had a partial response while five patients (27.7%) died during TPE treatment. Among the survivors, relapse of TTP occured in three patients (23%) and although these patients were treated again with TPE, all died. First-year survival rate was 41.2%. Our results indicate that TPE may be effective in the treatment of some patients with grade 2-3 HSCT-associated TTP.

Posttransplantation thrombotic thrombocytopenic purpura: a single-center experience and a contemporary review

OBJECTIVE

To assess the activity of von Willebrand factor-cleaving protease (vWF-CP) in patients with thrombotic thrombocytopenic purpura (TTP) complicating bone marrow transplantation (BMT) and peripheral blood stem cell transplantation (PBSCT).

PATIENTS AND METHODS

From March 1, 1999, to June 30, 2001, allogeneic and autologous hematopoietic stem cell transplantation was performed in 118 and 400 patients, respectively. We reviewed risk factors for development of posttransplantation TTP and measured vWF-CP activity during active TTP in 10 recipients.

RESULTS

The incidence of TTP after allogeneic and autologous transplantation was 6.8% (8/118) and 0.25% (1/400), respectively. Among the allogeneic transplant recipients, the incidence of TTP after nonmyeloablative (NMA) PBSCT, matched unrelated donor BMT, and sibling BMT or PBSCT was 15.4% (2/13), 11.8% (2/17), and 4.5% (4/88), respectively. Of the 10 patients with TTP, 9 (90%) had received extensive prior therapy, including autologous transplantation in both NMA recipients. Acute graft-vs-host disease (GVHD) prophylaxis consisted of cyclosporine and methotrexate in most affected patients. The vWF antigen level was elevated in all patients, and no patients showed evidence of vWF-CP deficiency. During active TTP, 6 patients had grade II-IV acute GVHD, 1 had extensive chronic GVHD, and 4 had cytomegalovirus viremia. Risk factor analysis for development of TTP showed that transplant type (NMA and matched unrelated donor) and source of stem cells (bone marrow vs peripheral blood stem cell) were significant.

CONCLUSIONS

Posttransplantation TTP was not found to be associated with severe vWF-CP deficiency. The elevated levels of vWF antigen are consistent with diffuse endothelial injury likely because of multiple interacting factors such as extensive prior therapy, GVHD, cyclosporine, and reactivation of cytomegalovirus. The disorder appears to be more frequent among patients with, or at risk for, acute GVHD, suggesting a possible role in the pathogenesis. Nonmyeloablative transplantation does not appear to confer a lesser risk, possibly for these reasons.

Thrombotic microangiopathy in blood and marrow transplant patients receiving tacrolimus or cyclosporine A

BACKGROUND

Cyclosporine A (CSA) and tacrolimus (FK-506) are both associated with thrombotic microangiopathy (TMA) in allogeneic BMT recipients, although it is not known which drug is more likely to cause the syndrome. The optimal treatment of BMT-associated TMA is also not known.

STUDY DESIGN AND METHODS

To estimate the risks, predisposing factors, and outcomes of TMA, data were analyzed from two cohorts of BMT patients who had received CSA or FK-506 in our institution with the same clinical definition for TMA. TMA was diagnosed in 11 of 55 patients (CSA, 3 of 24; FK-506, 8 of 31).

RESULTS

The daily risk of developing TMA was 0.12 percent for patients receiving CSA and 0.26 percent for those receiving FK-506 (p = 0.16, chi-square). Among patients receiving FK-506, sibling donor BMT recipients were as likely to develop TMA as matched unrelated donor recipients. Serum CSA and FK-506 concentrations were not elevated above the therapeutic range in most patients with TMA. The blood urea nitrogen to serum creatinine ratio was elevated in patients with TMA. Despite daily plasmapheresis, 9 of 11 patients died without resolution of TMA; however, the causes of death were multifactorial, including GVHD. Histologic evidence for TMA was absent in 1 patient who died with persistent clinical signs attributed to microangiopathy.

CONCLUSIONS

In this study, a high incidence of TMA was found in patients receiving either CSA or FK-506 following BMT, with uniform diagnostic criteria and strict monitoring. Neither drug showed elevated levels in most patients with TMA. Plasmapheresis was unsuccessful in reversing most cases of TMA.

Transplantation-associated thrombotic microangiopathy: twenty-two years later

A syndrome of microangiopathic hemolytic anemia, renal dysfunction and neurological abnormalities was first noted in bone marrow transplant recipients 22 years ago. Now known as transplantation-associated thrombotic microangiopathy (TA-TMA) to distinguish it from other thrombotic microangiopathies, this disorder responds poorly to conventional treatments for thrombotic thrombocytopenic purpura. In this review, we discuss the incidence and risk factors for TA-TMA and describe a pathophysiologic model of the disorder based on results obtained from laboratory models of the thrombotic microangiopathies. We conclude by suggesting possible approaches to the early diagnosis and treatment of TA-TMA based on this model that may warrant testing in future clinical trials.

Late response to cyclosporine in refractory thrombotic thrombocytopenic purpura

Plasma exchange (PEX) with fresh frozen plasma, usually in association with steroid therapy, has been shown to be the first-line treatment of thrombotic thrombocytopenic purpura. It works by removing ultralarge von Willebrand factor (vWF) multimers and inhibitory antibody and by supplying normal protease. For patients with disease refractory to PEX, there is no standardized treatment. Limited and sporadic success with different therapies (vincristine sulfate, prostacyclin, intravenous immunoglobulins, splenectomy) has been described. We report the case of a woman who developed refractory disease after an initial response to PEX and despite a very high number of PEX procedures performed. Low activity (< 5%) of serum vWF-cleaving protease and a low level of protease inhibitor were documented. The patient had a slow but sustained response when oral cyclosporine was administered concomitantly with PEX, which was slowly tapered. The activity of serum vWF-cleaving protease normalized. At relapse, treatment with cyclosporine, added after the failure of steroids and PEX, led to a lasting response. It is possible that in some cases cyclosporine therapy must be of particularly long duration before being considered ineffective.

Thrombotic thrombocytopenic purpura after allogeneic stem cell transplantation: a survey of the European Group for Blood and Marrow Transplantation (EBMT)

A survey was carried out among the European Group for Blood and Marrow Transplantation (EBMT) centres to determine the incidence, risk factors, treatment and outcome of thrombotic thrombocytopenic purpura (TTP) following allogeneic haematopoietic stem cell transplantation. TTP was defined as the simultaneous occurrence of red cell fragmentation, laboratory findings of haemolysis, red cell transfusion requirement and de novo or persistent thrombocytopenia caused by consumption, in the absence of disseminated intravascular coagulation. Forty-five centres reported all patients (n = 406) transplanted between July and December 1996. Twenty-three patients developed TTP; the risk of developing TTP was 6.7% at 2 years (95% CI: 4.1% to 9.3%). The median time of onset was 44 d (range 13-319) post transplantation. Significant risk factors for the development of TTP were female gender (P = 0.005) and an unrelated donor (P = 0.046). To treat TTP, cyclosporin administration was discontinued in 10 cases, plasma exchanges were performed in five cases and 12 patients received plasma infusions without plasma exchange. TTP resolved in 13 of the 23 patients (57%). The only factor predictive of resolution of TTP was the absence of nephropathy. Seven patients (30%) were alive at follow-up of 38-45 months from the onset of TTP. Sixteen patients died; the causes were multiple, only three patients had TTP as a central factor. The median time to death was 41 d (range 1-762 d) from the onset of TTP. TTP is a relatively frequent complication of allogeneic stem cell transplantation and it is associated with high mortality, though death is usually caused by multiple factors.

Transplantation-associated thrombotic microangiopathy is associated with transplantation from unrelated donors, acute graft-versus-host disease and venoocclusive disease of the liver

Transplantation-associated thrombotic microangiopathy (TA-TMA) has been associated with significantly reduced survival following allogeneic bone marrow transplantation. In this study we describe the course and response to plasma exchange therapy of TA-TMA as well as risk factors for its' development. Twenty-five patients who underwent plasma exchange therapy were matched to fifty control patients selected for transplant indication and stage of disease at the time of transplant. Transplant indications were acute myeloid leukemia, acute lymphoblastic leukemia, chronic myeloid leukemia, aplastic anemia, myelodysplastic syndrome and multiple myeloma. Groups were well balanced with respect to disease status, age at time of transplant and use of radiation-based conditioning. TA-TMA was diagnosed a median of 27 days after transplantation and neurological abnormalities were present in ten cases. Patients received a median of 10 (range 2-43) plasma exchange treatments. Hematological responses were recorded in eight cases. Risk factors for the development of TA-TMA included transplantation from unrelated donors (p = 0.002), hepatic venoocclusive disease (VOD) (p = 0.034), grade 2-4 acute graft-versus-host disease (GVHD) (p = 0.042) and bacteremia with diphtheroid organisms (p = 0.009). Only hepatic VOD (p = 0.0026) and grade 2-4 acute GVHD (p = 0.0436) remained significant risk factors for later development of TA-TMA in a multivariate logistic regression model. The median survival of patients with TA-TMA was 66 (range 32-733) days while that of unaffected patients was 742 (range 15-2392) days after transplantation. Only one patient with TA-TMA remains alive 733 days after transplantation.

Acute life-threatening toxicity of cancer treatment

Although patients with cancer may derive much benefit from treatment, they are at risk for developing life-threatening complications. Hypersensitivity reactions can be severe, as in the case of anaphylaxis with L-asparaginase. Cardiac toxicities consist of arrhythmias with various drugs, hemorrhagic myocarditis with cyclophosphamide and ifosfamide, cardiomyopathy with anthracyclines, and pericardial disease. Acute respiratory failure may occur as a result of ARDS caused by ATRA or cytarabine, from interstitial fibrosis, or from pulmonary veno-occlusive disease. Hemorrhagic cystitis caused by cyclophosphamide and ifosfamide can be severe and result in exsanguination if unresponsive to treatment. Disseminated intravascular coagulation and thrombotic microangiopathy can produce thrombotic or hemorrhagic complications. Gastrointestinal toxicities include significant hepatotoxicity with a variety of drugs and development of acute surgical abdomen.

BMT: Bone Marrow Transplant Associated Thrombotic Microangiopathy

Thrombotic microangiopathy is a severe microvascular disorder which may occur in up to 70% of patients undergoing bone marrow transplant. Clinically the term thrombotic microangiopathy encompasses a wide spectrum of syndromes, most importantly the thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). Thrombotic microangiopathy is characterized by the presence of thrombocytopenia, microangiopathic hemolytic anemia, renal impairment, neurological disturbances and multiorgan failure. Several causative agents have been advocated as triggering factors for bone marrow transplant associated thrombotic microangiopathy, including cyclosporine, FK506, the use of total body irradiation, infections and the presence of severe graft-versus-host disease. Plasma exchange represents the standard treatment for patients who develop TTP/HUS after bone marrow transplant, however, the mortality rate still remains high despite aggressive therapy.

Thrombotic thrombocytopenic purpura-like syndromes following bone marrow transplantation: an analysis of associated conditions and clinical outcomes

The diagnosis and treatment of thrombotic thrombocytopenic purpura (TTP) in patients following BMT are often uncertain and unsuccessful. To better understand the evaluation and management of these patients, we describe 17 patients treated with plasma exchange for a presumptive diagnosis of TTP following BMT during a 10 year period, 1989-1998. Because of the uncertainty of the diagnosis, these patients are described as having a 'TTP-like syndrome'. All 17 patients had received an allogeneic BMT. Comparison with the other 245 patients who had an allogeneic BMT during the same period demonstrated that patients with a TTP-like syndrome more frequently had unrelated and/or HLA-mismatched donors, and had also experienced more serious complications: grade III-IV acute GVHD and systemic bacterial, fungal, and viral infections. Three months after the diagnosis of the TTP-like syndrome, only four of 17 patients (24%) were alive; currently only one patient survives. These data emphasize: (1) the diagnosis of TTP following BMT is uncertain because of the presence of multiple BMT-associated complications. (2) The outcome of patients with TTP-like syndromes following BMT is poor. (3) Urgent intervention with plasma exchange when TTP is suspected following BMT may not always be appropriate. Alternative explanations for the signs and symptoms should be considered and treated aggressively.

Osteonecrosis of the femoral head after allogeneic bone marrow transplantation

A comparative retrospective analysis of 100 consecutive patients after bone marrow transplantation was performed with magnetic resonance imaging in addition to plain radiography for the development of osteonecrosis of the femoral head. The incidence and risk factors for osteonecrosis of the femoral head were identified, comparing various parameters concerning bone marrow transplantation between the groups with and without evidence of osteonecrosis. Nineteen (19%) of 100 patients had osteonecrosis of the femoral head develop. Four factors were found to be statistically significantly different between patients who had osteonecrosis develop and those who did not: younger age at the time of bone marrow transplantation, chronic graft-versus-host disease, cumulative dose of steroid, and intravenous pulse therapy with methylprednisolone. It was concluded that a low rate of complications and low dose steroid administration would reduce the incidence of osteonecrosis after bone marrow transplantation.

Therapeutic plasma exchange in patients suffering from thrombotic microangiopathy after allogeneic bone marrow transplantation

Thrombotic microangiopathy (TM) is a potentially fatal complication of allogeneic bone marrow transplantation (BMT). The underlying pathophysiology is thought to be generalized endothelial cell damage caused by several factors including conditioning treatment, cyclosporin A (CsA), or graft versus host disease (GVHD). In the present retrospective study, 6 patients suffering from Grade 2 BMT-TM at a mean of 62 days post BMT were treated by 3-15 daily sessions of therapeutic plasma exchange (TPE). In most sessions, cryosupernatant (CSN) of plasma, in some fresh frozen plasma (FFP) was used as the substitution fluid. All patients suffered from acute graft versus host disease (aGVHD) of the skin, which was treated by CsA. CsA was withdrawn in all patients. TPE caused a response in 4 of 6 patients evidenced by a decrease to Grade 0 (n = 3) or 1 (n = 1) BMT-TM. Only 1 patient had mild renal insufficiency which did not improve during TPE. While all patients were dependent on platelet transfusions at baseline, the platelet counts improved in 2 of 6 patients after the TPE course. One patient did not show any response to TPE with FFP, and his disease improved only after CSN was introduced as substitution fluid (Grade 0). Four patients were still alive 175-495 days post BMT, and 2 patients died about 2-3 weeks after the end of the TPE course, 1 from cachexia and 1 from systemic aspergillosis. In summary, in this pilot study, TPE positively influenced BMT-TM, especially if CSN was used as the substitution fluid.