Treatment of thrombotic thrombocytopenic purpura

Retrospective analysis comparing complication rates of centrifuge vs membrane-based therapeutic plasma exchange in the pediatric population

BACKGROUND

There are two conventional modalities used to perform therapeutic plasma exchange (TPE): centrifuge TPE (cTPE) or membrane TPE (mTPE). There is limited data on complications with mTPE.

OBJECTIVE

We sought to better understand the patient and machine complications of mTPE compared to cTPE. We hypothesize that our protocol for mTPE using heparin anticoagulation is well-tolerated.

METHODS

In this retrospective cohort study of children <21 years of age, we evaluated differences in patient and machine characteristics and complications between cTPE (with citrate anticoagulation) vs mTPE (with heparin anticoagulation).

RESULTS

Of the 105 patients who met inclusion/exclusion criteria, 63 received cTPE and 42 mTPE via Prismaflex. Those who used mTPE were younger (4.8 ± 2.8 years vs 15.2 ± 3.7 years, P = .0001) and weighed less (19.5 ± 10.6 vs 71.7 ± 28.5 kg, P = .0001). There were no significant differences in patient-related complications or indications for TPE between the two modalities. Of the 1031 therapies performed,1003 therapies were analyzed (646 using cTPE and 357 using mTPE) due to exclusion criteria. No significant difference in patient complications were detected between groups. Machine-related complications were infrequent in both approaches. More circuits clotted during mTPE than during cTPE (6.7% [24/357] vs 0% [0/646]; P < 0.001).

CONCLUSION

Although we use mTPE in smaller children, we showed low rates of complications that were not statistically different from cTPE performed in older children. While the overall rate of circuit clotting using mTPE was low, it occurred more commonly than with cTPE.

Evaluation and Management of Thrombotic Thrombocytopenic Purpura in the Emergency Department

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) is a dangerous condition that can be misdiagnosed in the emergency department.

OBJECTIVE

The purpose of this narrative review article is to provide a summary of the background, pathophysiology, diagnosis, and management of TTP, with a focus on emergency clinicians.

DISCUSSION

TTP is a disorder with microangiopathic hemolytic anemia, severe thrombocytopenia, and multiorgan ischemic injury. It may be acquired or hereditary, and is caused by a reduced amount or function of a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13), which is an enzyme involved in cleaving von Willebrand factor. The classic presentation of TTP includes fever, neurologic abnormalities, thrombocytopenia with purpura, microangiopathic hemolytic anemia, and acute renal injury. However, < 7% of cases have all of these findings present. Testing should include a complete blood count, complete metabolic panel, blood smear, coagulation panel, fibrinogen, D-dimer, lactate dehydrogenase, ADAMTS13 level, troponin, human immunodeficiency virus assessment, urinalysis, pregnancy test as appropriate, and electrocardiogram. Management includes hematology consultation if available, plasma exchange and corticosteroids, and treatment of end-organ complications. All patients require admission for treatment and close monitoring.

CONCLUSION

TTP is a potentially dangerous medical condition requiring rapid diagnosis and management. It is essential for emergency clinicians to know how to diagnose and treat this disorder.

Thrombotic microangiopathy with renal injury: an approach for the general physician

Thrombotic microangiopathy with renal dysfunction is a haematological and renal emergency warranting urgent diagnosis and intervention. As the potential underlying causes may be complex, assessment and management can be challenging for treating clinicians, and a timely and collaborative approach between general physicians, haematologists and nephrologists may be extremely helpful in order to optimise clinical outcomes. This paper will aim to build an understanding of different potential presentations of thrombotic microangiopathies and provide a practical framework for diagnosis and management, using a case-based discussion format, for acute and general physicians. Some aspects of subsequent specialist management are also discussed.

COVID-19 associated thrombotic thrombocytopenic purpura (TTP) ; A case series and mini-review

INTRODUCTION

Thrombotic microangiopathies are a group of disorders that are mainly related to endothelial dysfunction. This category of endothelial dysfunction results of several imbalances between platelets, endothelium and immune system, also cytokine production.

AIM OF THIS STUDY

To report cases with thrombotic thrombocytopenic purpura (TTP) and COVID-19 and review COVID-19 endothelial dysfunction literature.

METHODS

Primary laboratory data, peripheral blood smear, ADAMTS13 antigen activity level, and antibody ordered for each of these four patients. Treatments for COVID-19 administered for all patients. Traditional treatments for TTP also were administered.

RESULTS

There were numerous schistocytes (more than 5%) in peripheral blood smears for each patient. ADAMTS13 antigen activity level was below 10%, and ADAMTS13 antibody was elevated for each patient. COVID-19 PCR was positive for all patients, and CT-Scans were indicative of the involvement of COVID-19.

CONCLUSION

In this case series, we reported four COVID-19 patients who presented with signs and symptoms of anemia and thrombocytopenia, resulting in thrombotic thrombocytopenic purpura.

Thrombotic microangiopathy, DIC-syndrome and COVID-19: link with pregnancy prothrombotic state

For last months, humanity has faced a formidable unknown enemy, which is presented as a new coronavirus infection. Despite the fact that the causative agents of new diseases appear at a certain frequency and that the virus SARS-CoV-2 has certain common properties with its predecessors, at the moment we are dealing with a new unknown pathogenesis of the development of severe complications in patients with risk factors. A final understanding of pathological process mechanisms is the goal of the scientific community. Summarizing research data from different countries, it became obvious that in severe cases of viral infection, we are dealing with a combination of the systemic inflammatory response syndrome, disseminated intravascular coagulation and thrombotic microangiopathy (TMA). Thrombotic microangiopathy is represented by a group of different conditions in which thrombocytopenia, hemolytic anemia, and multiple organ failure occur. The article reflects the main types of TMA, pathogenesis and principles of therapy. The main participants in the process are described in detail, including the von Willebrand factor and ADAMTS-13. Based on the knowledge available, as well as new data obtained from patients with COVID-19, we proposed possible models for the implementation of conditions such as sepsis, TMA, and DIC in patients with severe new coronavirus infection. Through a deeper understanding of pathogenesis, it will be possible to develop more effective diagnosis and therapy.

Thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a clearly defined entity of the thrombotic microangiopathies (TMA), a heterogeneous group of disorders characterized by microangiopathic hemolytic anemia with red cell fragmentation, thrombocytopenia and organ dysfunction due to disturbed microcirculation. TTP is characterized by a severe deficiency of ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13), an enzyme responsible for physiological cleavage of von Willebrand factor (VWF). Organ dysfunction can be severe and life-threatening, and immediate start of appropriate therapy is necessary to avoid permanent damage or death. Until recently, therapeutic options were limited to symptomatic measures, which were not standardized or based on high scientific evidence. In recent years, not only considerable progress has been made in better diagnosis of TTP, but also new therapeutic strategies have been established. Initial treatment is still based on plasma exchange and symptomatic measures to protect organ function, but new concepts (immunosuppression, targeted anti-VWF or anti-complement therapy, replacement with recombinant enzymes) have recently demonstrated impressive advantages.

Changes in plasma von Willebrand factor and von Willebrand factor cleaving protease in thrombotic thrombocytopenic purpura: A case report

The present case report described a patient with thrombotic thrombocytopenic purpura (TTP), who presented to the China-Japan Union Hospital of Jilin University (Changchun, China), and the changes in plasma von Willebrand factor (vWF) and vWF cleaving protease (vWF-cp) observed during treatment. Computed tomography and diffusion-weighted magnetic resonance (MR) imaging of the brain, cerebral MR angiography and other experimental tests were performed and the patient was subsequently diagnosed with TTP. The patient underwent treatment with plasma exchange, glucocorticoids and supportive care. Hematologic and biochemical parameters began to gradually improve over the 12 days after admission; platelet count, serum creatinine and serum lactate dehydrogenase concentrations returned to their normal ranges, plasma vWF concentration decreased to normal levels over the 30 days after admission, and vWF-cp activity increased compared with the levels detected in healthy volunteers. Monthly rituximab treatment was administered 4 times following patient discharge to prevent relapse, and no recurrence was detected at the 20-month follow-up. Plasma exchange therapy is effective in patients with TTP. After low-dose rituximab treatment, recurrent TTP has not been detected found till now. In the present case, vWF concentration and vWF-cp activity were measured at 8, 10, 23 and 32 days after admission; compared with the control group, patient's vWF concentration gradually decreased and vWF-cp activity slowly increased, suggesting that the patient had a favorable prognosis and a low risk of recurrence.

Successful Treatment of Transplant Associated Thrombotic Microangiopathy (TA-TMA) with Low Dose Defibrotide

Transplant associated microangiopathy (TA-TMA) is a potentially serious complication of stem cell transplantation. Though stopping calcineurin/mTOR inhibitor is the first step in managing TA-TMA, this is not always adequate. The pathophysiology of TA-TMA is different from microangiopathy seen in other settings. Many drugs have been used in TA-TMA with modest responses. Defibrotide has been explored in TA-TMA in the past with good results. However, its availability is erratic and cost of therapy very high. Hence its routine use in low middle income country (LMIC) is financially demanding. We report the use of low dose defibrotide safely and successfully in this case series. This is pertinent more to LMIC's and warrants prospective evaluation.

Acute thrombotic thrombocytopenic purpura after pneumococcal vaccination

We report the case of a 68-year-old woman with acute thrombotic thrombocytopenic purpura (TTP) that developed after pneumococcal vaccination. She was found in a confusional state with high fever 15 days after vaccination. Laboratory data showed hemolytic anemia and thrombocytopenia, and blood smear showed fragmented erythrocytes. TTP was diagnosed based on the clinical presentation, and was subsequently confirmed by the absence of ADAMTS13 activity and the presence of inhibitor against ADAMTS13 in serum. She was successfully treated using plasma exchange and corticosteroids, and no recurrence has been identified. This appears to represent the first report of TTP following pneumococcal vaccination.

Management of pregnancy-associated thrombotic thrombocytopenia purpura

Thrombotic thrombocytopenia purpura (TTP) is an infrequent but serious disease. Pregnancy is a known risk factor for presentation or relapse of TTP. Difficulties in differentiating TTP from preeclampsia/HELLP (hemolysis, elevated liver enzymes and low platelets) syndrome, and current treatment recommendations are discussed in this case report. A woman with previously treated and stable TTP had a relapse at 36 weeks' gestation. Careful surveillance led to an early diagnosis. Severe disease in the peripartum period was treated successfully with cryosupernatant plasma-based plasmapheresis and platelet transfusion, with good maternal and neonatal outcomes. Cryosupernatant plasma is a viable alternative to fresh frozen plasma for plasmapheresis for TTP and may offer some therapeutic and logistical advantages. Platelet transfusion can be undertaken safely if needed to prevent or treat significant hemorrhage.

SLE with diffuse alveolar hemorrhage, microangiopathic hemolytic anemia and acute renal failure

In SLE patients with diffuse alveolar hemorrhage (DAH) and acute renal failure (ARF), the most common associated renal injury is proliferative lupus nephritis. We report a case of a young SLE patient with DAH and ARF who was successfully treated with a course of therapeutic plasma exchange (TPE) plus pulse IV cyclophosphamide. Kidney biopsy revealed an alternative diagnosis.

Rituximab therapy to prevent relapse in chronic relapsing thrombotic thrombocytopenic purpura (TTP) in a child

Our patient first developed thrombotic thrombocytopenic purpura (TTP) at age 10 years with an initial platelet count of 10,000/microL. She achieved remission with plasmapheresis (PE), but suffered 2 relapses in the next 2 years, each approximately 1 year from PE, with ADAMTS13 levels of <5%. Early in her third remission, with vincristine (weekly x 4 doses) and prednisone (for 2 weeks) her ADAMTS13 increased to 99% in 24 weeks, but decreased to <4% in the next 38 weeks. After 4 weekly doses of rituximab (375 mg/m(2)), her ADAMTS13 level reached 101% in 9 weeks and has remained consistently above 97% on bimonthly monitoring for more than a year. She remains in continuous clinical and hematologic remission with an ADAMTS13 level of 108% at 60 weeks from rituximab therapy and 124 weeks from her second relapse. This case report suggests that monitoring ADAMTS13 level at regular intervals in recurrent TTP may help us identify patients at risk for further relapse; and such a relapse may be prevented, or at least delayed with timely rituximab therapy, thus reducing morbidity from relapsed TTP and its treatment.

A 9-month-old infant with acquired idiopathic thrombotic thrombocytopenic purpura caused by inhibitory IgG-autoantibody to ADAMTS13

Although acquired idiopathic thrombotic thrombocytopenic purpura (ai-TTP) is rare in children, the authors present the case of a 9-month-old boy with ai-TTP showing severe deficiency of ADAMTS13 activity by its inhibitory IgG-autoantibody (4.8 Bethesda units/mL). Plasma exchange therapy was clinically effective but transient. Deficient activity of ADAMTS13 with the presence of its inhibitor persisted for 7 months after the initial diagnosis. However, other laboratory findings improved gradually with steroid (pulse) therapy. The hitherto insufficiently characterized clinical settings of ai-TTP during early childhood underscore the importance of measuring ADAMTS13 activity and its inhibitors for differential diagnosis in patients with thrombocytopenia of unknown etiology.

Efficacy and Safety Profile of Solvent/Detergent Plasma in the Treatment of Acute Thrombotic Thrombocytopenic Purpura: A Single-Center Experience

BACKGROUND: Thrombotic thrombocytopenic purpura (TTP) is a rare clinical disorder which was associated with poor prognosis for a long time. The outcome has been improved by the consistent introduction of thera-peutic plasma exchange (TPE) as standard treatment of TTP. PATIENTS AND METHODS: We describe our experience in the use of solvent/detergent-treated plasma (SDP) for TPE in TTP. We retrospectively analyzed acute TTP epi-sodes in 8 patients (mean age = 27 years, range 18-44 years) treated with TPE using SDP with regard to tolerability and efficacy. RESULTS: All 8 patients were positive for anti-ADAMTS-13 antibody. Seven out of 8 had a se-vere ADAMTS-13 deficiency. All patients responded rapidly to SDP TPE with an increase in platelet count to above 150 x 10(9)/l. Hemolytic anemia disappeared over the treatment period. Approximately 2,000 l SDP were used for more than 500 treatments. Treatment with SDP was well tolerated; none of the patients experienced an adverse drug reaction after exposure to SDP. No major complications occurred even after multiple TPE. CONCLUSION: Our investigations suggest that TPE using SDP as replacement fluid is an effective treatment for TTP. The data described also indicate that SDP might offer the benefit of reducing adverse drug reactions.

Thrombotic thrombocytopenic purpura and adult onset Still's disease

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) has a high mortality rate if undiagnosed and untreated. Although recent literature supports the role of ADAMTS13 (a disintegrin-like metalloproteinase with thrombospondin type 1 repeats), the von Willebrand factor cleaving protease, in the pathogenesis of the disease, many aspects of the disease remain a mystery. Various drugs and autoimmune conditions, such as systemic lupus erythematosus and the antiphospholipid syndrome, have been observed in association with TTP. Adult onset Still's disease (AOSD) has been reported less frequently in association with TTP.

PRESENTATION

We report the case of a 43-year-old African American man who initially presented with fever and joint pain and was later diagnosed with TTP. He responded initially to plasma exchange, but never achieved complete remission. He eventually required splenectomy for complete resolution of symptoms of TTP, but the arthritis never resolved, resulting in several admissions for joint pain. The arthritis was eventually diagnosed as AOSD.

DISCUSSION

Literature review shows that the autoimmune diseases usually associated with TTP include systemic lupus erythematosus and the antiphospholipid syndrome. Eight reports of AOSD with TTP have been reported, but our case is unique in several aspects. Previous case reports have described TTP occurring in patients with known AOSD; here, we describe TTP preceding or coinciding with the onset of AOSD. Interestingly, the patient's AOSD-associated arthritis responded to plasma exchange, but did not resolve after splenectomy. The coincident onset of AOSD and TTP in this patient lead us to suspect a common pathophysiologic pathway in the pathogenesis for both of these diseases.

Inherited ADAMTS13 deficiency: unique presentation and treatment

A 3-year-old male presented with severe thrombocytopenia and microangiopathic hemolytic anemia in conjunction with severe bilateral otitis media. After laboratory analysis, a diagnosis of inherited ADAMTS13 deficiency was proven. Rather than treating with prophylactic fresh frozen plasma, to date the patient has been successfully treated with single-donor, directed plasma infusions in response to early signs of relapse. It may be reasonable to consider observational and reactive care rather than prophylactic care in some cases of inherited ADAMTS13 deficiency.

Successful liver-kidney transplantation in two children with aHUS caused by a mutation in complement factor H

A 12-month-old boy and his 16-year-old aunt became acutely ill 6 months apart and were diagnosed to have atypical hemolytic uremic syndrome (aHUS). Genetic analysis revealed heterozygous R1215Q mutation in complement factor H (CFH) in both patients. The same mutation was found in five healthy adult relatives indicating incomplete penetrance of the disease. The patients developed terminal renal failure and experienced reversible neurological symptoms in spite of plasma exchange (PE) therapy. In both cases, liver-kidney transplantation was successfully performed 6 months after the onset of the disease. To minimize complement activation and prevent thrombotic microangiopathy or overt thrombotic events due to the malfunctioning CFH, extensive PE with fresh frozen plasma was performed pre- and perioperatively and anticoagulation was started a few hours after the operation. No circulatory complications appeared and all four grafts started to function immediately. Also, no recurrence or other major clinical setbacks have appeared during the postoperative follow-up (15 and 9 months) and the grafts show excellent function. While more experience is needed, it seems that liver-kidney transplantation combined with pre- and perioperative PE is a rational option in the management of patients with aHUS caused by CFH mutation.

Syndrome d'œdème pulmonaire lésionnel aigu post-transfusionnel (Trali) après perfusion de plasma frais congelé au cours d'une microangiopathie thrombotique congénitale

INTRODUCTION

Transfusion-related acute lung injury is a post-transfusion interstitial lung injury.

CASE REPORT

We reported a post-transfusion acute lung injury in a 23-years old woman having a chronic thrombotic microangiopathy related to an ADAMTS 13 constitutional deficiency receiving monthly plasma infusion for six years. The temporal relationship between the lung injury and the infusion of fresh frozen plasma led to the diagnosis of transfusion-related acute lung injury. The finding in the donor of the transfused plasma of an anti-HLA class II antibody recognizing HLA-DR52 present on leucocytes of the recipient suggests a causal relationship between this antigen-antibody conflict and the triggering of the TRALI. This chronic pathologic state requiring monthly plasma transfusions for thrombotic accident prevention raises the question of the selection of plasma obtained from non-immunized donors.

CONCLUSION

The occurrence of a post transfusion pulmonary edema without cardio-vascular overload, must lead to consider a TRALI especially in predisposing clinical situations. In the case reported the role of constitutional ADAMTS 13 deficiency in genesis of TRALI is considered.

Protein�A immunoadsorption therapy for refractory, mitomycin�C?associated thrombotic microangiopathy

BACKGROUND

Mitomycin C-associated thrombotic microangiopathy (TMA) has a poor prognosis with limited therapeutic options. Most patients die within 4 months of diagnosis due to pulmonary or renal failure. Here, a patient resistant to total plasma exchange (TPE) and immunosuppressive therapy with glucocorticoids, rituximab, vincristine, and splenectomy who was successfully treated with protein A immunoadsorption is described.

CASE REPORT

A 29-year-old woman developed a TMA after chemotherapy with mitomycin C. She presented with thrombocytopenia, pulmonary edema, hemolytic anemia with presence of schistocytes, and renal failure. Immediate TPE (>120 times) and immunosuppressive therapy with glucocorticoids, however, did not improve her clinical situation. Furthermore, she was refractory to subsequent immunosuppressive therapy with rituximab and vincristine and laparoscopic splenectomy. Finally, after 12 cycles of extracorporeal protein A immunoadsorption with a commercially available immunoadsorption system (Immunosorba, Fresenius AG), platelet counts increased with disappearance of hemolytic syndromes.

CONCLUSION

Extracorporeal protein A immunoadsorption with the Immunosorba system emerges as a potentially effective and safe treatment for refractory mitomycin C-associated TMA with only moderate side effects. This therapeutic option may be considered at an early state of the disease to prevent extensive immunosuppression.

Thrombotic thrombocytopenic purpura induced by metronidazole vaginal gel

Thrombotic thrombocytopenic purpura (TTP) is a rare, life-threatening disorder characterized by microangiopathic hemolytic anemia and thrombocytopenia. Patients with TTP often have an increased reticulocyte count, elevated serum lactate dehydrogenase level, and decreased serum haptoglobin level. Other symptoms include fever, neurologic changes, and renal abnormalities. Thrombotic thrombocytopenic purpura may occur in association with various disorders or conditions, including infections, malignancies, pregnancy, and autoimmune disorders. The disorder may also be drug induced; however, antibiotics are not commonly implicated. A 58-year-old Hispanic woman went to her gynecology clinic and was prescribed metronidazole 0.75% vaginal gel for possible vaginal infection. Three days later, she came to the emergency department with complaints of chest pain and blood in her urine. A complete blood cell count was remarkable for a hemoglobin level of 10.2 g/dl (which decreased to 5.5 g/dl the next day), hematocrit of 29.1% (which decreased to 15.9% the next day), and platelet count of 11 x 10(3)/mm3. Based on these laboratory abnormalities and other clinical findings, the patient was diagnosed with TTP. She was treated with plasmapheresis and corticosteroids and initially responded; however, she relapsed twice, which required increasing the frequency of plasmapheresis, and vincristine and rituximab therapy. The patient's condition resolved, and she experienced no other complications. Use of the Naranjo adverse drug reaction probability scale indicated a probable relationship between the metronidazole vaginal gel and the development of TTP. This patient had developed TTP after only one exposure to metronidazole vaginal gel. Clinicians should be aware of this life-threatening adverse reaction to a commonly prescribed drug.

Severe limb necrosis: primary thrombotic microangiopathy or “seronegative” catastrophic antiphospholipid syndrome? A diagnostic dilemma

An episode of gastroenteritis triggered severe necrosis of all extremities in a previously asymptomatic male. Hepatic and renal involvement were also manifest, while the hematological picture was one of thrombotic microangiopathic hemolytic anemia. Antiphospholipid antibodies were negative. He responded well to a combination of plasma exchange, anticoagulation (heparin), parenteral steroids, and antibiotics, as well as vasodilators (prostacycline) and hyperbaric oxygen, but died because of a cerebral hemorrhage. The differential diagnosis included thrombotic thrombocytopenic purpura/hemolytic-uremic syndrome, or seronegative catastrophic antiphospholipid (Asherson's) syndrome. The dangers of administering such a combination of therapies with anticoagulation, as well as vasodilatation (prostacycline) and hyperbaric oxygen, are highlighted by the case report and emphasized.

The evidence-based use of FFP and cryoprecipitate for abnormalities of coagulation tests and clinical coagulopathy

There continues to be a general but unfounded enthusiasm for fresh frozen plasma (FFP) or frozen plasma (FP) usage across a range of clinical specialties in hospital practice. Plasma for transfusion is most often used where there are abnormal coagulation screening tests, either therapeutically in the face of bleeding, or prophylactically in nonbleeding patients prior to invasive procedures or surgery. Little evidence exists to inform best therapeutic transfusion practice, and most studies describe plasma use in a prophylactic setting. Laboratory abnormalities of coagulation are considered by many clinicians to be a predictive risk factor for bleeding prior to invasive procedures or in other clinical situations where bleeding risk exists, and plasma for transfusion is presumed to improve the laboratory results and reduce this risk. However, most guideline indications for the prophylactic use of plasma for transfusion are not supported by evidence from good-quality randomized trials. Arguably, the strongest randomized controlled trial (RCT) evidence indicates that prophylactic plasma for transfusion is not effective across a range of different clinical settings, and this is supported by data from nonrandomized studies in patients with mild to moderate abnormalities in coagulation tests. There is a need to undertake new trials evaluating the efficacy and adverse effects of plasma, both in bleeding and non-bleeding patients, to understand whether the presumed benefits outweigh the real risks. In addition, new hemostatic tests that better define the risk of bleeding and monitor the effectiveness of the use of FFP should be validated. Last, there is an opportunity to develop effective educational strategies aimed at addressing understanding and compliance with recommendations in guidelines.

Bench-to-bedside review: pulmonary-renal syndromes--an update for the intensivist

The term Pulmonary-renal syndrome refers to the combination of diffuse alveolar haemorrhage and rapidly progressive glomerulonephritis. A variety of mechanisms such as those involving antiglomerular basement membrane antibodies, antineutrophil cytoplasm antibodies or immunocomplexes and thrombotic microangiopathy are implicated in the pathogenesis of this syndrome. The underlying pulmonary pathology is small-vessel vasculitis involving arterioles, venules and, frequently, alveolar capillaries. The underlying renal pathology is a form of focal proliferative glomerulonephritis. Immunofluorescence helps to distinguish between antiglomerular basement membrane disease (linear deposition of IgG), lupus and postinfectious glomerulonephritis (granular deposition of immunoglobulin and complement) and necrotizing vasculitis (pauci-immune glomerulonephritis). Patients may present with severe respiratory and/or renal failure and require admission to the intensive care unit. Since the syndrome is characterized by a fulminant course if left untreated, early diagnosis, exclusion of infection, close monitoring of the patient and timely initiation of treatment are crucial for the patient's outcome. Treatment consists of corticosteroids in high doses, and cytotoxic agents coupled with plasma exchange in certain cases. Renal transplantation is the only alternative in end-stage renal disease. Newer immunomodulatory agents such as those causing TNF blockade, B-cell depletion and mycophenolate mofetil could be used in patients with refractory disease.