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Thrombotic thrombocytopenic purpura (TTP) is a fatal thrombotic disease caused by a marked decrease in the activity of ADAMTS13, a von Willebrand factor cleaving protease. In congenital TTP, ADAMTS13 activity is decreased by an abnormality in ADAMTS13, and in acquired TTP, by anti-ADAMTS13 autoantibody. Death from thrombosis in the acute phase has been an issue with conventional treatment of acquired TTP by plasma exchange or immunosuppressive therapy. However, the advent of caplacizumab, an anti-VWF nanobody, has made it possible to suppress thrombus formation and is expected to improve survival rates. In addition, some case series have shown the efficacy of caplacizumab without plasma exchange for acquired TTP, and this approach is being investigated in clinical trials. Fresh-frozen plasma is transfused to supply ADAMTS13 for congenital TTP, but frequent transfusions over a long period of time can lead to problems such as infection and allergic reactions. Novel therapies such as recombinant ADAMTS13 products and gene therapy are now under development, and show promise for future clinical use.

A 27-year-old woman was diagnosed with idiopathic thrombocytopenic purpura in the neonatal period, and was admitted to our hospital after presenting with impaired consciousness, purpura, nausea and vomiting, with a platelet count of 10×10 9 /l. Congenital thrombotic thrombocytopenic purpura (cTTP) was suspected on the basis of recurrent thrombocytopenia and impaired consciousness, so tests for ADAMTS13 activity and inhibitor were performed. ADAMTS13 activity was severely decreased, ADAMTS13 inhibitor was negative, and platelet count increased after transfusion of fresh frozen plasma. These findings and the results of genetic testing done on all family members led to a diagnosis of cTTP. cTTP requires differential diagnosis even in adults. If a patient diagnosed with ITP in childhood has a history or findings that suggest cTTP during follow-up observation, it is necessary to actively consider ADAMTS13 testing.

Immune checkpoint inhibitor (ICI)-induced thrombocytopenias are rare immune-related adverse events (irAE), but ICI-related thrombotic thrombocytopenic purpura (TTP) is extremely rare. A 79-year-old woman with non-small cell lung cancer received maintenance therapy with the anti-human PD-L1 monoclonal antibody durvalumab. Four weeks after the last infusion, she developed overt TTP. Remission was achieved by plasma exchange and prednisolone, and the patient has now been recurrence-free for over 12 months. To our knowledge, this is the first report of TTP occurring as an irAE of durvalumab.

Thrombotic thrombocytopenic purpura (TTP) is a poor prognosis disease caused by platelet thrombi produced in the microvessels throughout the body. The thrombus is mainly composed of von Willebrand factor (VWF) and platelets. Acquired TTP is an autoimmune disease wherein autoantibodies against ADAMTS13, a VWF-cleaving enzyme, are produced and ADAMTS13 activity is markedly decreased. Plasma exchange using fresh-frozen plasma as a replacement fluid effective against acquired TTP was reported in 1991. Since then, plasma exchange and corticosteroids have been the standard of care in Japan. Caplacizumab, which is a monoclonal antibody against the VWF A1 domain, finally became available for use in 2022, and the number of cases is still increasing in Japan. A clinical trial of recombinant ADAMTS13 product is being conducted for congenital TTP, and an era is expected to come in the future when plasma exchange will no longer be necessary.

The patient was a 78-year-old man. After 4 courses of GEM plus nab-PTX therapy for multiple recurrent liver metastases after pancreatic body cancer surgery, the patient was aware of general malaise and edema of the extremities. Blood tests showed pancytopenia, and he was admitted to the hospital with a diagnosis of chemotherapy-induced pancytopenia. On the second day, hemolytic anemia with crushed red blood cells was observed, suggesting thrombotic microangiopathy (TMA). Considering the possibility of thrombotic thrombocytopenic purpura(TTP), the patient was started on plasma exchange with steroids. After 7 days of plasma exchange, his thrombocytopenia, hemolytic anemia, and renal dysfunction improved, and he was discharged from the hospital on the 28th day. Although GEM-induced TMA is a life-threatening complication, there is no established treatment for it. We report a case of GEM-induced TMA that was successfully treated with plasma exchange.

Thrombotic microangiopathy (TMA) is a pathological condition characterized by platelet thrombi-induced generalized microvascular occlusion, thrombocytopenia, and microangiopathic hemolytic anemia. TMA includes the life-threatening diseases thrombotic thrombocytopenic purpura (TTP) and hemolytic-uremic syndrome (HUS). TTP is different from HUS in that it has a severe deficiency in ADAMTS13 activity. Congenital TTP is caused by a lack of plasma ADAMTS13 activity caused by genetic mutations, and acquired TTP is caused by a secondary deficiency caused by autoantibodies. In Japan the only product approved for the treatment of congenital TTP is fresh frozen plasma containing ADAMTS13. Recombinant ADAMTS13 may provide a new treatment option for congenital TTP. The first-line treatment for acquired TTP is plasma exchange. Rituximab treatment should be considered for patients who are refractory or have relapsed. Caplacizumab is a nanobody that specifically targets von Willebrand factor. ISTH recently published guidelines recommending that caplacizumab be added to the initial treatment for acquired TTP. Atypical HUS (aHUS) is related with the dysregulation of the complement alternative pathway. Eculizumab, a monoclonal antibody that inhibits C5, was the first drug approved for aHUS, and it was found to be well-tolerated by patients and effective in clinical use. TMA is classified based on its etiology, and specific treatments for targeting various etiologies are now available.

Thrombotic thrombocytopenic purpura (TTP) is a rare and potentially life-threatening disease that is characterized by microangiopathic hemolytic anemia, consumptive thrombocytopenia, and ischemic organ damage resulting from the formation of platelet-rich thrombi in the microvasculature. It is especially related to a severe deficiency of ADAMTS13, the specific von Willebrand factor-cleaving protease. Thus, <10% of the normal activity of ADAMTS13 is an essential diagnostic marker for establishing a diagnosis of TTP. TTP can be of congenital form that is termed the Upshaw-Schulman syndrome (USS) that is caused by genetic abnormality of ADAMTS13 and acquired form that is caused by autoantibodies against ADAMTS13. The congenital form is treated with the infusion of fresh frozen plasma, and the treatment of the acquired form involves plasma exchange combined with immunosuppressive therapy that uses corticosteroids and rituximab. Recently, the efficacy and safety of new drugs caplacizumab, single-domain antibody against ADAMTS13, and recombinant ADAMTS13 products have been reported in large-scale clinical trials conducted in other countries. These results suggested the better outcome in the treatment for the patients with TTP in the near future.

Acquired thrombotic thrombocytopenic purpura (aTTP) is a life-threatening systemic thrombotic microangiopathy characterized by the presence of anti-ADAMTS13 antibodies (inhibitor). Here we report the case of a patient with refractory aTTP successfully treated with cyclosporine. A 69-year-old man presenting with hematuria and petechiae was referred to our hospital; he was disoriented and febrile. Laboratory results revealed Coombs-negative hemolytic anemia, thrombocytopenia, and renal failure. Undetectable ADAMTS13 activity and presence of anti-ADAMTS13 antibodies (inhibitor) confirmed the diagnosis of aTTP. Despite performing plasma exchange and administering prednisolone and rituximab (375 mg/m 2 ), we were unable to restore his platelet counts to the normal level. Therefore, he was treated with cyclophosphamide (500 mg/bodyweight), vincristine (1.4 mg/m 2 ), bortezomib (1.3 mg/m 2 ), and cyclosporine (2.5 mg/kg). After the cyclosporine therapy, his platelet counts gradually normalized. Continuous cyclosporine maintenance therapy led to complete disappearance of the inhibitor. Therapeutic strategies for refractory aTTP have not yet been established. Further investigations are warranted to establish a therapeutic strategy for refractory aTTP.

In this article, I mainly review the molecular targeted therapy for thrombotic thrombocytopenic purpura (TTP). TTP is one of thrombotic microangiopathies (TMA), which demonstrate hemolytic anemia with red blood cell destruction and thrombocytopenia. Another TTP, hemolytic uremic anemia (HUS) reveals bloody stood and acute kidney failure. As it is difficult to correctly diagnose TTP based on clinical symptoms alone, a confirmation of whether ADAMTS13 activity is lower than 10% is required. In the past few years, TTP was designated as an intractable disease by law, and the clinical application of ADAMTS13 test and rituximab became labeled in Japan. Currently, we are expecting that recombinant ADAMTS13 and caplacizumab for immune TTP will be applied.

The key clinical symptoms of thrombotic thrombocytopenic purpura (TTP) are severe thrombocytopenia, microangiopathic hemolytic anemia, and organ ischemia/infarction due to microthrombi. Hemolytic anemia in TTP is characterized by mechanical damage to red blood cells. TTP is caused by a severe deficiency of ADAMTS13 activity, which is caused by mutations in the ADAMTS13 gene (congenital TTP) or by autoantibodies affecting the function or clearance of ADAMTS13 (immune TTP). Patients with congenital TTP receive fresh frozen plasma (FFP) transfusion for the supplementation of ADAMTS13. Meanwhile, those with immune TTP receive plasma exchange therapy using FFP for the supplementation of ADAMTS13 and the removal of anti-ADAMTS13 autoantibodies. Corticosteroid therapy is concurrently administered to suppress autoantibody production. In terms of novel treatment, the use of rituximab, a humanized anti-CD20 monoclonal antibody, in patients with immune TTP was approved by the Japanese health insurance in 2020. Novel and promising drugs are currently developed. A first-in-human study of recombinant ADAMTS13 for congenital TTP was reported in 2017. Caplacizumab is a humanized nanobody that inhibits the interaction between von Willebrand factor and platelets. This drug can prevent early thrombus formation and organ damage in patients with immune TTP. Therefore, these novel drugs can improve mortality in patients with TTP.

Thrombotic thrombocytopenic purpura (TTP) is a thrombotic microangiopathy (TMA) caused by ADAMTS13 deficiency. Although the name of TTP is well known, most hematologists find its diagnosis and treatment difficult because it is ultrarare. TTP is an acute-onset and fatal disorder. Approximately 90% of TTP patients die within 2 weeks of onset without proper medical treatment. Although most doctors may remember being taught the five TTP symptoms (fever, transient central nervous system symptoms, hemolytic anemia, thrombocytopenia, and kidney dysfunction) at medical school, only 7% of TTP patients present with all five symptoms. Thus, TTP must be suspected in patients with microangiopathic hemolytic anemia and thrombocytopenia, and plasma therapy must be initiated as soon as possible after ordering the ADAMTS13 test. In this article, I describe how to differentially diagnose TMA as well as the standard and the updated therapy, such as rituximab and caplacizumab, for TTP treatment.

A 30-year-old woman who was 14 weeks pregnant was admitted to our hospital due to purpura, nasal bleeding, and abdominal pain. She was diagnosed with acquired thrombotic thrombocytopenic purpura (TTP) based on the presence of hemolytic anemia, thrombocytopenia, decreased ADAMTS 13 activity (<0.01 IU/ml), and high ADAMTS 13 inhibitor levels (4.8 BU/ml). Plasma exchange (PE) and steroid therapy were immediately administered. However, because she did not respond to these therapeutic approaches, rituximab was additionally administered on the sixth day of treatment. The level of ADAMTS 13 inhibitor increased to 12.5 BU/ml on the seventh day. Renal insufficiency, disturbed consciousness, and genital bleeding did not improve in spite of daily PE, steroid therapy, and second dose of rituximab. She finally died after sudden convulsions on the 14th day. Although the treatment outcomes of TTP have remarkably improved, some cases are refractory to therapy. Establishment of adequate treatment strategies for acquired TTP in pregnant women is required.

Both TTP and aHUS are officially designated as intractable diseases by a new Japanese law in 2015. New clinical practice guidelines for TTP and aHUS have been published. Both conditions share some common pathophysiology such as thrombotic microangiopathy. Unfortunately, most professionals in the fields of hematology/oncology are unaware of these diseases. Therefore, I will provide an updated overview of TTP and aHUS in this article.

Although thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease, appropriate diagnosis and treatment result in the higher survival rate of >80%. TTP is usually suspected with thrombocytopenia and hemolytic anemia and is confirmed by a reduced activity of a disintegrin-like and metalloprotease with thrombospondin type 1 motif 13 (ADAMTS13) <10%. TTP is classified as acquired if a patient tests positive for anti-ADAMTS13 autoantibodies, and as congenital if ADAMTS13 gene abnormalities are identified. In patients with congenital TTP, fresh frozen plasma (FFP) transfusion for the supplementation of ADAMTS13 is performed. On the other hand, in patients with acquired TTP, plasma exchange therapy using FFP is conducted to supplement ADAMTS13 and remove anti-ADAMTS13 autoantibodies. Besides, corticosteroid therapy is often administered in conjunction with plasma exchange to suppress autoantibody production. In 2017, we aim to provide "diagnostic and treatment guidelines for TTP 2017 in Japan". In this review, we describe new developments in diagnosis and management of TTP, which are not discussed in the guidelines.

An 81-year-old man presenting with fever, neurological symptoms, thrombocytopenia, and hemolytic anemia was diagnosed with acquired idiopathic thrombotic thrombocytopenic purpura (TTP). His disintegrin-like and metalloproteinase with thrombospondin type 1 motifs 13 (ADAMTS13) activity was <1% and the ADAMTS13 inhibitor titer was 3.2 BU/ml. He received plasma exchange and steroid administration until remission was achieved. Seven months later, he suffered from paralysis of the right hand, hemolytic anemia, and thrombocytopenia. We confirmed TTP recurrence based on ADAMTS13 activity <1% and an ADAMTS13 inhibitor titer of 19.4 BU/ml. Four infusions of rituximab were administered in addition to plasma exchange and steroid pulse therapy. Platelet count recovery was observed within 5 days. No severe side effects related to rituximab occurred. Although rituximab has not been approved for TTP in Japan, we report the efficacy and safety of rituximab in an elderly patient with recurrent TTP. We suggest that rituximab therapy should be started as soon as possible for recurrent TTP in patients with high titers of ADAMTS13 inhibitor.

Acquired thrombotic thrombocytopenic purpura (TTP) is caused by autoantibodies against ADAMTS13. TTP patients run a rapidly fatal course unless immediate plasma exchange (PEX) is initiated upon diagnosis. Herein, we report a 72-year-old man with TTP, which developed after he underwent artificial blood vessel replacement surgery for an abdominal aneurysm with impending rupture. In the perioperative period, the patient received several platelet transfusions for severe thrombocytopenia (minimum platelet count: 0.6×10(4)/μl). Thereafter, he was admitted to our department for rapidly progressing coma with multiple cerebral infarctions, and was transferred to the ICU. Based on the tentative diagnosis of TTP, we immediately began PEX and steroid pulse therapy. The diagnosis was confirmed thereafter by markedly reduced ADAMTS13 activity (<0.5%) and his being positive for the ADAMTS13 inhibitor. We performed PEX for five consecutive days and administered high-dose prednisolone (PSL). On the second hospital day (HD), his platelet count rose along with improvement of his consciousness level. The ADAMTS13 inhibitor was not detected on the 10th HD. TTP did not relapse and his general condition improved despite tapering of PSL. In this case, by closely monitoring ADAMTS13-related parameters and minimizing the number of plasma exchanges, the patient was able to achieve a remission without the use of boosting inhibitors.

A 71-year-old male patient began FOLFOX6 plus panitumumab treatment for unresectable recurrent rectal cancer. He developed thrombocytopenia after 2 courses of treatment and therefore a platelet transfusion was performed. The day after transfusion, the patient developed jaundice and hematuria. His lactate dehydrogenase levels had increased and a peripheral blood smear review revealed the presence of schistocytes. Anti-ADAMTS13 antibodies were present, and there was a reduction in ADAMTS13 activity. The patient was diagnosed with thrombotic thrombocytopenic purpura and treated with a plasma exchange. The day after the plasma exchange, his clinical condition rapidly worsened and he died. Thrombocytopenia due to chemotherapy often appears as myelosuppression. If conditions such as jaundice, indirect bilirubinemia, or hematuria appear during the course of chemotherapy, this condition must be considered as a differential diagnosis.

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disorder classified with a type of thrombotic microangiopathy (TMA). TTP is caused by a deficiency of von Willebrand factor-cleaving protease called ADAMTS13 (a disintegrin-like and metalloprotease with a thrombospondin type1 motif 13). Low ADAMTS13 levels result in increased ultra-large von Willebrand factor multimers (UL-VWFM), which induce platelet adhesion and thrombosis. Congenital TTP (Upshaw-Schulman syndrome: USS) is an inherited disorder of ADAMTS13, and the other more commonly is an acquired TTP caused by autoantibodies against ADAMTS13. This article reviews the progress of ADAMTS13 activity measurement and the resulting changes in the diagnosis and treatment of TTP.

Thrombotic microangiopathies (TMAs) are microvascular occlusive disorders characterized by thrombocytopenia, microangiopathic hemolytic anemia, and systemic or intrarenal aggregation of platelets. TMA includes two major disorders: thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). It is now well known that TTP is caused by deficiency of ADAMTS13 activity due to mutations in the ADAMTS13 gene (Upshaw-Schulman syndrome, USS) or by acquired autoantibodies against ADAMTS13. On the other hand, more than 90% of HUS cases are associated with Shiga toxin-producing E. coli infection. The remaining 10% of patients have what is called atypical HUS (aHUS). Most aHUS cases are caused by uncontrolled complement activation due to genetic mutations in the alternative pathway, such as complement factor H, complement factor I, membrane cofactor protein (CD46), and C3. TMAs also develop in association with various underlying diseases and conditions (so-called secondary TMA) including connective tissue disorders, transplantation (hematopoietic stem cell, liver, kidney), malignancy, pregnancy, and certain drugs. Plasma exchange is the first-line therapy for most patients with TMAs. Early plasma exchange improves TMA outcomes. Monoclonal therapies, rituximab in TTP and eculizumab in aHUS, are now frequently being used as second-line treatment options.

An 89-year-old woman presented to our hospital with hemolytic anemia and a high titer of cold agglutinins. Red cell agglutination was observed on a blood smear. Agglutination visibly decreased after warming the blood; therefore, the patient was diagnosed with cold agglutinin disease (CAD). Bone marrow aspiration revealed no infiltration of malignant cells. Computed tomography indicated moderate splenomegaly. The patient had neither an infection nor autoimmune disease. Initial steroid therapy was ineffective and hemolysis worsened. Meanwhile, thrombocytopenia, delirium, fever, and schistocytes in the blood were observed. The progression of hemolysis was attributed not only to CAD but also to coexisting thrombotic thrombocytopenic purpura (TTP) because of the decreased ADAMTS 13 level. Autopsy revealed mild paraaortic lymphadenopathy and splenomegaly. Microscopic examination revealed lymphoma cell infiltration in the spleen, liver, bone marrow, and paraaortic lymph nodes. These observations suggested that TTP and CAD were both secondary complications. This case highlights the importance of an autopsy for the detection of latent lymphoma, which can be difficult to diagnose before the patient's death. Careful examination to exclude lymphomas is important in patients with CAD at the time of diagnosis.

We report here on a case of a 27-year-old woman in her first pregnancy. She was diagnosed with idiopathic thrombocytopenic purpura (ITP) at the age of 14 years. At 36 weeks of gestation, she was admitted to our hospital due to thrombocytopenia. We initially suspected ITP exacerbated by pregnancy. Laboratory results revealed mild anemia, thrombocytopenia (5.0×10(9)/l), and slightly elevated liver enzymes and lactate dehydrogenase. The next day, hemoglobin fell to 6.6 g/dl. Thrombotic thrombocytopenic purpura (TTP) was suspected on the basis of hemolytic anemia with schistocytes and a negative Coombs' test. Plasma exchange and methylprednisolone were initiated immediately. ADAMTS13 analysis showed a severe deficiency in ADAMTS13 activity but no inhibitors. At Day 6, the platelet count rose to 223×10(9)/l and she delivered a live baby by cesarean section. Currently, the patient receives fresh frozen plasma infusions every 2 weeks due to suspected Upshaw-Schulman syndrome.

Thrombotic thrombocytopenic purpura (TTP) is a life-threatening disease that is a rare complication of thienopyridine treatment, especially clopidogrel. Here we report a case of clopidogrel-associated TTP. A 77-year-old male initially complained of petechiae on his legs 6 weeks after clopidogrel treatment following coronary artery stenting. He was admitted 4 weeks later with slurred speech and low-grade fever. Laboratory findings showed severe thrombocytopenia, hemolytic anemia with fragmented red cells, renal dysfunction and severe deficiency of ADAMTS13 activity with the presence of the inhibitor. Based on the clinical course and laboratory findings, he was diagnosed with TTP and underwent plasma exchange, followed by improvement of symptoms and laboratory abnormalities after 7 courses of plasma exchange. Nevertheless, the patient died of sepsis due to perforated small intestinal diverticulitis 89 days after admission. Thienopyridine-associated TTP usually occurs within 12 weeks after initiation of the therapy. Physicians should therefore be aware of this fatal complication associated with clopidogrel therapy and frequent blood tests, every 2 weeks during the first 12 weeks, is recommended for early diagnosis.

A 47-year-old woman was transported to our hospital because of vomiting and syncope after breakfast. Physical examination revealed icterus and anemia of bulbar conjunctivas, and abnormal neurological findings were detected. Laboratory data indicated marked anemia and thrombocytopenia (Hb 5.2 g/dl, Plt. 0.6×10(4)/μl), but no leukocyte abnormalities were found. Transaminase was slightly elevated, and serum indirect bilirubin in was also elevated. Based on these data, we initially suspected Evan's syndrome, which involves idiopathic thrombocytopenic purpura with autoimmune hemolytic anemia. So we transfused red blood cells, performed platelet transfusion, and administered steroids, but there was no response to these therapies. On the 4th day of admission, she developed a stroke followed by coma. After the stroke, we diagnosed the case as thrombotic thrombocytopenic purpura (TTP) because laboratory findings showed diminished activity of ADAMTS 13 (a disintegrin-like metalloproteinase with thrombospondin type 1 motifs 13) and ADAMTS 13 antigen. It is important to suspect TTP when hemolytic anemia with thrombocytopenia is observed, and to check the activity and antigen of ADAMTS13 immediately for the diagnosis. Platelet transfusion should be done cautiously in these cases.

We report a patient with refractory idiopathic thrombotic thrombocytopenic purpura (TTP) who was successfully treated with rituximab. A 50-year-old woman was referred to our hospital with progressive psychoneurotic symptoms, hemolytic anemia and thrombocytopenia. The diagnosis of TTP was confirmed by the absence of ADAMTS13 activity with the presence of circulating ADAMTS13 inhibitor. High-dose steroid therapy and plasma exchange were performed. Despite 21 sessions of plasma exchange, however, there was no remarkable improvement. We then administered rituximab. Fifteen days after the first infusion of rituximab, she achieved complete remission and ADAMTS13 activity increased up to 14%. The patient has remained in remission for more than 9 months.

The main stream of treatment for rheumatic disease is pharmacotherapy. Corticosteroids, DMARDs, the immunosuppressive agents and biologics are the gold standard of the treatment. However, some cases showing resistance to these treatments exist, and the potential for side effects exists in all of these pharmacotherapies. Furthermore, there are cases in which pharmacotherapy cannot be effectively used due to organ derangement. Apheresis is totally different from pharmacotherapy as a concept, and it is a treatment to control disease activity by removing the factors which contribute to the pathogenicity. The synchronized therapy of apheresis and pharmacotherapy is the treatment that may result in a more beneficial effect of treatment. This review introduces the experiences as an overall approach to better, safer management for rheumatic diseases.

Although not common, thrombotic thrombocytopenic purpura (TTP) is one of the most serious complications in patients with systemic lupus erythematosus (SLE). This study aimed to characterize the association between SLE and TTP by examining clinical features and treatment outcomes. We evaluated eight patients diagnosed over two years in our hospital. The mean disease duration of SLE until TTP onset was 13.2 years. One patient had a simultaneous diagnosis of SLE and TTP. CNS lupus and lupus nephritis were involved in 6 patients, respectively. The mean value of the SLE disease activity index was 40.5. Five out of 7 patients who have been examined the von Willebrand factor cleaving protease showed moderately decreased activity. Seven out of the 8 patients were treated with plasmapheresis, and 7 received immunosuppressive therapy including cyclophosphamide and rituximab. Seven patients recovered, but one died from an exacerbation of the disease. These data indicated that plasmapheresis and immunosuppressive therapy improved prognosis of TTP associated with SLE.

We reported a Japanese first case of thrombotic thrombocytopenic purpura (TTP) induced by clopidogrel, a newly developed antithrombotic drug, marketed in May 2006 in Japan. This 80 years old woman developed cerebral infarction and suffered from Broca's aphasia and right hemiparesis. Clopidogrel was started on Day 6 after the onset. On Day 10, four days after the administration of clopidogrel, two egg-sized purpura with marked decrease in platelet count was found. The purpura extended over the entire body in next few days. Despite total seven times of plasma exchange, platelet count did not normalize. Twenty four days after the onset of TTP, the patient developed central catheter infection and died of sepsis. TTP will become a lethal side effect of clopidogrel, when diagnosis and treatment are late. Because it is assumed that the mechanism of clopidogrel induced TTP differs from that of ticlopidine, we should establish firm treatment urgently.

A 26-year-old man was referred to our hospital with vomiting and high fever. He was disoriented and laboratory results showed microangiopathic hemolytic anemia (Hb 7.1 g/dl) and severe thrombocytopenia (15 x 10(3)/microl). The diagnosis of thrombotic thrombocytopenic purpura (TTP) was established. The activity of von Willebrand cleaving protease (ADAMTS13) was found to be remarkably low (<0.5%) and the high activity of the inhibitor (11.0 Bethesda U/ml) was detected, confirming the diagnosis of typical acquired TIP. Although he had been successfully treated with daily plasma exchange and methylprednisolone, he relapsed after a week. To this therapeutic strategy we added four weekly doses of rituximab (375 mg/m2) and two weekly doses of vincristine (1 mg/m2) simultaneously. The response was very rapid and complete, that is, the platelet count recovered to normal seven days after the first rituximab and vincristine treatment. The patient maintains complete remission nine months later under the administration of 17.5 mg prednisolone. Recovery of the plasma ADAMTS13 activity was clearly correlated with the decrease or disappearance of the inhibitor activity. Combination of rituximab and vincristine therapy would appear to be very effective against refractory TTP.

ADAMTS13 specifically cleaves unusually large von Willebrand factor (VWF) multimers, which induce platelet thrombi formation under high shear stress. The determination of plasma levels of ADAMTS13 activity is prerequisite for a differential diagnosis of thrombotic microangiopathies (TMAs). Here, we describe a unique and highly sensitive enzyme immunoassay of ADAMTS13 activity for routine laboratory use. ADAMTS13 hydrolyses the peptide bond between Y1605 and M1606 of VWF. In this enzyme immunoassay, a recombinant fusion protein (GST-VWF73-His) is used as a substrate. We have produced a panel of mouse monoclonal antibodies (anti-N10 mAb) that specifically recognizes the peptide containing Y1605 which is the C-terminal edge residue newly generated by the enzymatic cleavage. Using horseradish peroxidase-conjugated anti N10 mAb, a standard enzyme activity assay was established by ELISA. This assay was highly sensitive, and the detection limit was 0.5% of the normal. Further, an inhibitor of ADAMTS13 was measured to a level of 0.1 Bethesda U/ml. The activity measured by our novel assay and by the classic VWF multimer assay showed high correlation. We have also established ADAMST13 antigen ELISA assay using two clones of anti-ADAMST13 monoclonal antibody. The plasma antigen level of ADAMTS13 has generally good correlate to the plasma activity, but the several samples from acquired TTP patients with below 3% activity showed apparently high antigen level from 5 to 30%. Here, we have established a convenient and highly sensitive enzyme immunoassay for ADAMTS13 activity. This assay will be introduced for routine laboratory work in transfusion medicine.

We report a patient with severe thrombotic thrombocytopenic purpura (TTP) refractory to plasmapheresis who was successfully treated with rituximab. A 57-year-old male patient was referred to our department for further differential diagnosis and treatment of anemia and severe thrombocytopenia. Progressive psychoneurotic symptoms, hemolytic anemia, thrombocytopenia, renal function insufficiency and fever led us to the diagnosis of TTP. ADAMTS13 activity was below 3% and an inhibitor for ADAMTS13 was detected. Treatment with plasmapheresis and high-dose steroid was initiated but without clinical benefit. Two weeks following the initiation of plasmapheresis, we decided to treat the patient with 7 cycles of rituximab. No severe rituximab-related adverse effects were observed. After treatment with rituximab, the disease remitted, and the ADAMTS13 activity level increased. The patient has remained in complete remission for more than 1 year. Our data suggest that rituximab may be the optimal immunosuppressive therapy for refractory thrombotic thrombocytopenic purpura caused by an anti-ADAMTS 13 inhibitor.

A 69-year-old man of thrombotic thrombocytopenic purpura (TTP) associated with ticlopidine was reported. The patient initially complained of dysarthria and left hemiparesis one month after oral administration of ticlopidine. These motor symptoms were followed by gradual deline in level of consciousness. On admission, he was in apallic state with focal cerebral signs, accompanied by low-grade fever, and purpuric eruptions. Laboratory findings showed remarkable thrombocytopenia, hemolytic anemia, and renal dysfunction. The patient received diagnosis of TTP based on Moschcowitzs criteria. Prompt initiation of plasma exchange dramatically improved the patient's clinical symptoms. In this case, decreased activities of a disintegrin and metallo proteinase with thrombospondin type 1 motifs 13 (ADAMTS13) in plasma and anti-ADAMTS13 IgG antibodies were detected. Serial diffusion weighted MRI with six-day interval starting from the onset showed two interesting findings. First, appearance and disappearance of scattered high intensity areas were observed in the cerebellum, corpus callosum, cerebral white matter, and neocortex. Second, these lesions roughly corresponded to border-zone infarct in distribution. Cranial MRI findings of TTP in the literature could be classified into the following four groups: 1) multiple infarction caused by microthrombi; 2) infarction caused by occulusion of an intracranial main artery; 3) reversible edema involving the cerebral white matter; and 4) unremarkable finding without specific abnormality. This case could be classified into the group 1. Based on the diffusion weighted MRI findings of this case, a previous pathological report and recent elucidations of clinical conditions, it is hypothesized that TTP is a predisposition for resembling the border-zone infarction in group 1. The border-zone distribution of transient high intensity areas in diffusion weighted MRI in this case could be explained by either high resistant vascules zone or impaired clearance of emboli, taking an autopsy case report into consideration.

Ticlopidine is an antiplatelet agent that interferes with platelet membrane function by inhibiting adenosine diphosphate-induced platelet activation. It is used in an increasing number of cases of cerebrovascular disease, unstable angina, coronary artery stenting, and peripheral vascular diseases. It has rare but serious adverse reactions, including thrombotic thrombocytopenic purpura (TTP). TTP is a life-threatening disease, characterized by Moschcowitz's pentad: thrombocytopenia, microangiopathic hemolytic anemia, fluctuating neurological signs, renal failure, and fever. Recent advances in elucidating the proteolytic processing of plasma von Willebrand factor (VWF) multimers have established assays for VWF-cleaving protease (VWF-CP) activity and its inhibitor(autoantibodies). These assays apparently demonstrated that TTP patients have defective enzymatic activity with or without presence of the inhibitor. VWF-CP is now identified as a metalloproteinase belonging to the ADAMTS (A Disintegrin And Metalloproteinase domain, with ThromboSpondin type 1 motif) family, termed ADAMTS13. Cases of ticlopidine-associated TTP were first reported in 1991. This complication occurs in 1 in 1600 to 1 in 5000 patients who receive ticlopidine. It is known that they develop TTP within 2 to 8 wk of starting ticlopidine treatment and show severely deficient of ADAMTS13 activity with the presence of the inhibitor. These results suggest that ticlopidine or its metabolites induce the production of autoantibodies against ADAMTS13. As treatment, discontinuation of ticlopidine therapy and rapid initiation of plasma exchange is effective: the majority of patients completely recover and relapse is uncommon. It is thus recommended that physicians should perform complete blood count every 2 weeks for 12 weeks for rapid diagnosis. Physicians and patients should be aware of this fatal but curable complication of ticlopidine therapy.

We report a case of thrombotic thrombocytopenic purpura (TTP) with a positive Coombs' test. A 59-year-old female was admitted to our hospital in February, 1997 with symptoms of heart failure. Ultrasound cardiography showed moderate pericardiac effusion and she was diagnosed as having pericarditis. After admission she had anorexia and her urine volume was reduced. Laboratory tests showed anemia and thrombocytopenia. Her Coombs' test result was positive. Her renal function gradually worsened and her conscious level was reduced. We diagnosed her as TTP and judged that she needed hemodialysis. We performed plasma exchange and started steroid therapy. The renal biopsy was compatible with TTP. After treatment, her level of consciousness improved, but her renal function did not improve. On the 51st hospital day she fell into acute respiratory distress syndrome (ARDS) and entered ICU. We considered ARDS caused by infection and continued treatment, but she died of shock and lactate acidosis. Activity of von Willebrand factor-cleaving protease in our case was 15% before the first PE, and 25 % just before death. A case of TTP without collagen disease usually shows a negative Coombs' test result. We think that this was a rare case in which autoimmune hemolytic anemia was supervened with TTP.

We experienced a patient with Duchenne muscular dystrophy (DMD) complicated by thrombotic thrombocytopenic purpura (TTP). This patient exhibited abrupt high fever, renal dysfunction and thrombocytopenia from February 2, 2002. Hemolysis was also indicated by indirect dominant hyperbilirubinemia, although hemoglobin was only slightly decreased. No central nervous system signs and symptoms were detected. TTP was suggested by these findings and confirmed by decreased activity (21%) of von Willebrand factor cleaving protease activity. Plasma exchange was performed for 4 days from February 5, and enabled recovery. Thrombosis, such as cerebral and lung infarction, has occasionally been seen in DMD. Recently, several findings associating muscle degeneration with hypercoagulation have been reported, for example, a strong correlation between serum CK level and FDP. In seven cases of DMD with pulmonary infarction, transient elevation of serum CK was detected prior to LDH elevation. However, there have been no reports of TTP in DMD patients. Since serum CK was not elevated during our patient's clinical course, it is unlikely that muscle degeneration played a role in TTP in this patient. It should be noted that endothelial abnormalities have been reported in DMD, since endothelial injury is considered a fundamental factor in TTP.

A 19-year-old girl was admitted to our hospital because of general fatigue, headache and purpura. A number of her laboratory findings suggested hemolytic anemia and thrombocytopenia. Direct/indirect Coombs tests gave negative results. Although the patient had no neurological or renal abnormalities, peripheral blood smears showed marked red cell fragmentation, and therefore she was diagnosed as having thrombotic thrombocytopenic purpura (TTP). Fresh frozen plasma (FFP) was transfused daily. The thrombocytopenia and hemolysis immediately improved, but worsened again after reduction of the FFP transfusion. Plasma exchange was instituted every other day, but the patient's condition worsened. Palsy and consciousness disturbance developed, and finally she lapsed into a coma. Daily plasma exchange and methylprednisolone pulse therapy were performed, together with weekly vincristine therapy, and this led to a gradual improvement in the patient's condition. However, several attempts at weaning from plasma exchange resulted in exacerbation of the TTP activity. Therefore oral cyclosporine A was started and splenectomy was performed. After these interventions, despite transient relapse, the patient was successfully weaned off the FFP transfusion, and she is now in remission. Because in this case splenectomy and cyclosporine A resulted in sustained remission of TTP that was refractory to intensive plasma therapy, an autoimmune mechanism may have been involved in the pathogenesis.