Microangiopathic haemolytic anaemia in metastasizing malignant tumours is not associated with a severe deficiency of the von Willebrand factor-cleaving protease

Tumour-Associated Microangiopathic Haemolytic Anaemia with Thrombocytopenia: A Narrative Review and Case Study

Thrombotic microangiopathy (TMA) is a category of diseases consisting of thrombocytopenia, microangiopathic haemolytic anaemia, and widespread occlusive microvascular thrombosis. We report two cases of a thrombotic microangiopathic syndrome associated with non-invasive mucinous cysts and mucinous adenocarcinoma. TMA was treated in both cases by surgical removal of the tumours. We hypothesise that mucin secretion in the case of non-invasive mucinous cysts and paraneoplastic secretion of antibodies in the case of mucinous adenocarcinomas are the causes of endothelial damage with thrombocytopenia and microangiopathic haemolytic anaemia. Finally, patients with TMA who exhibit unusual clinical characteristics or weak responses to plasma exchange should be examined for an underlying tumour. Tumour treatment is the preferred therapy for tumour-associated TMA.

Management of hematological patients requiring emergency chemotherapy in the intensive care unit

Hematological malignancies may require rapid-onset treatment because of their short doubling time, notably observed in acute leukemias and specific high-grade lymphomas. Furthermore, in targeted onco-hematological scenarios, chemotherapy is deemed necessary as an emergency measure when facing short-term, life-threatening complications associated with highly chemosensitive hematological malignancies. The risks inherent in the disease itself, or in the initiation of treatment, may then require admission to the intensive care unit (ICU) to optimize monitoring and initial management protocols. Hyperleukocytosis and leukostasis in acute leukemias, tumor lysis syndrome, and disseminated intravascular coagulation are the most frequent onco-hematological complications requiring the implementation of emergency chemotherapy in the ICU. Chemotherapy must also be started urgently in secondary hemophagocytic lymphohistiocytosis. Tumor-induced microangiopathic hemolytic anemia and plasma hyperviscosity due to malignant monoclonal gammopathy represent infrequent yet substantial indications for emergency chemotherapy. In all cases, the administration of emergency chemotherapy in the ICU requires close collaboration between intensivists and hematology specialists. In this review, we provide valuable insights that aid in the identification and treatment of patients requiring emergency chemotherapy in the ICU, offering diagnostic tools and guidance for their overall initial management.

Case Report: Thrombotic-Thrombocytopenic Purpura Following Ipilimumab and Nivolumab Combination Immunotherapy for Metastatic Melanoma

A man in his early 50s presented with small bowel obstruction, requiring emergency laparoscopic small bowel resection for the metastatic melanoma of the jejunum with no identifiable primary lesion. One week after his first treatment with ipilimumab and nivolumab, he presented with diffuse abdominal pain, constipation, and fatigue. A computerized tomography scan did not identify a cause for his symptoms. This was rapidly followed by thrombocytopenia on day 11 and then anemia. He commenced intravenous corticosteroids for a suspected diagnosis of immune-related thrombocytopenia. On day 15, a generalized onset motor seizure occurred, and despite plasmapheresis later that day, the patient died from fatal immune-related thrombotic thrombocytopenic purpura (TTP). This was confirmed with suppressed ADAMTS13 (<5%) testing on day 14. Immune-related TTP is a rare and, in this case, fatal immune- related adverse event. Further studies are required to identify additional immunosuppressive management for immune-related TTP.

Thrombotic Microangiopathy: A Rare Breast Cancer-associated Complication Treated Successfully With Doxorubicin and Cyclophosphamide

BACKGROUND

Thrombotic microangiopathy (TMA) is a clinical syndrome consisting of hemolytic anemia, thrombocytopenia, and presence of schistocytes on peripheral blood smear secondary to disorders of systemic microvascular thrombosis. Malignancy-associated TMA is a rare entity and shares clinical features with that of HUS and TTP usually seen in patients with metastatic cancer, tumor cell infiltration of the bone marrow and/or response to cancer-directed therapy.

CASE REPORT

We present a rare case of TMA secondary to breast cancer without evidence of bone marrow infiltration responsive to doxorubicin and cyclophosphamide treatment, after failed plasmapheresis with prednisone and later, eculizumab.

CONCLUSION

Despite being a rare manifestation of metastatic carcinoma, early identification and treatment are essential to improving survival.

[Breast cancer-related thrombotic microangiopathy: A review]

Thrombotic Microangiopathies (TM) have been described since the 1960s. They are characterized by presence of mechanical haemolytic anemia associated with peripheral thrombocytopenia. TM in cancer can be related to several causes, whose cancer himself: cancer-related microangiopathic haemolytic anaemia (MAHA). Incidence of cancer related MAHA remains unknown. Cancer-related MAHA are mainly observed in mucin-producer adenocarcinomas, such as gastric (half of reported cases) and breast cancer. We conducted a review of all original published cases of TM reported in breast cancer, and we specifically investigated BC-MAHA cases. A Medline search identified 158 MAHA cases including 118 BC-MAHA, and 40 drug-related MAHA. Most of BC-MAHA occur in disseminated cancers, mainly with medullar involvement, and/or bone metastasis. Patients typically suffer from poor general state, bone pain, and/or dyspnea. Laboratory abnormalities such as myelemia or erythromyelemia in peripheral blood are frequently observed. Incidence of coagulation disorders is increased, compared to other MAHA causes. BC-MAHA prognosis is dramatically poor. Treatments classically used in other MAHA causes, such as plasmapheresis or immunoglobulins, are inefficient. Urgent anti-neoplastic therapy may be the only effective treatment, associated to symptomatic therapies (transfusions, blood pressure control).

Characteristics and outcome of breast cancer-related microangiopathic haemolytic anaemia: a multicentre study

BACKGROUND

Cancer-related microangiopathic haemolytic anaemia (MAHA) is a rare but life-threatening paraneoplastic syndrome. Only single cases or small series have been reported to date. We set up a retrospective multicentre study focusing on breast cancer-related MAHA.

METHODS

Main inclusion criteria were known diagnosis of breast cancer, presence of schistocytes and either low haptoglobin or cytopenia and absence of any causes of MAHA other than breast cancer, including gemcitabine- or bevacizumab-based treatment. Patient characteristics, treatments and outcome were retrieved from digital medical records.

RESULTS

Individual data from 54 patients with breast cancer-related MAHA were obtained from 7 centres. Twenty-three (44%) patients had a breast tumour with lobular features, and most primary tumours were low grade (grade I/II, N = 39, 75%). ER+/HER2-, HER2+ and triple-negative phenotypes accounted for N = 33 (69%), N = 7 (15%) and N = 8 (17%) cases, respectively. All patients had stage IV cancer at the time of MAHA diagnosis. Median overall survival (OS) was 28 days (range 0-1035; Q1:10, Q3:186). Independent prognostic factors for early death (≤ 28 days) were PS > 2 (OR = 7.0 [1.6; 31.8]), elevated bilirubin (OR = 6.9 [1.1; 42.6]), haemoglobin < 8.0 g/dL (OR = 3.7 [0.9; 16.7]) and prothrombin time < 50% (OR = 9.1 [1.2; 50.0]). A score to predict early death displayed a sensitivity of 86% (95% CI [0.67; 0.96]), a specificity of 73% (95% CI [0.52; 0.88]) and an area under the curve of 0.90 (95% CI [0.83; 0.97]).

CONCLUSIONS

Breast cancer-related MAHA appears to be a new feature of invasive lobular breast carcinoma. Prognostic factors and scores may guide clinical decision-making in this serious but not always fatal condition.

The role of ADAMTS-13 and von Willebrand factor in cancer patients: Results from the Vienna Cancer and Thrombosis Study

BACKGROUND

Cancer-associated venous thromboembolism (VTE) is an important complication in the course of a malignant disease. Low ADAMTS-13 (a disintegrin-like and metalloproteinase with thrombospondin type 1 motif 13) and increased von Willebrand Factor (VWF) levels in cancer patients have been described numerously.

OBJECTIVES

Investigation of the influence of ADAMTS-13 and VWF on the probability of VTE and survival in malignancy.

PATIENTS/METHODS

In the framework of the ongoing prospective Cancer and Thrombosis Study (CATS) ADAMTS-13 activity and VWF antigen levels were investigated in cancer patients.

RESULTS

In total, 795 patients with various tumor types (364 female/431 male, median age 62 years) were included; of those, 56 developed VTE and 359 patients died during a median follow-up time of 730 days. The hazard ratio (HR) of VTE per doubling of VWF level was 1.56 (95% confidence interval [CI] 1.13-2.16) in multivariable competing risk analysis. ADAMTS-13 levels showed no correlation with the incidence of VTE in univariate competing risk analysis. The HR of mortality per doubling of VWF level was 1.46 (95% CI 1.28-1.66) and per SD increment of ADAMTS-13was 0.90 (95% CI 0.81-1.00) in multivariable Cox regression analysis. Patients with VWF >75th percentile and concomitant low (<25th percentile) or medium (25-75th percentile) ADAMTS-13 values had the highest probability of mortality (HR 4.31 and 4.75, respectively).

CONCLUSIONS

High VWF levels were significantly associated with the risk of developing VTE in cancer patients, whereas ADAMTS-13 was not. Low ADAMTS-13 and increased VWF levels were independently associated with worse overall survival.

Heparin-induced thrombocytopenia associated with thrombotic microangiopathy

Some cases of thrombotic microangiopathy (TMA) are refractory to plasma exchange therapy (PE) with persistence or recurrence of thrombocytopenia. We report two patients suffering from TMA of different aetiologies (associated with disseminated malignancy, typical haemolytic uraemic syndrome) with recurrent or persistent thrombocytopenia despite adequate therapy including PE. Since both patients were exposed to unfractionated heparin, heparin-induced thrombocytopenia (HIT) was suspected as a cause. Pretest probabilities for HIT were intermediate. ELISA for PF4/heparin antibodies was strongly positive in both cases, and HIT was confirmed by heparin-induced platelet activation assay. Anticoagulation with lepirudin was initiated, with subsequent rapid increase of the platelet count.

TMA might represent a predisposition for HIT. This could be due to TMA-related platelet activation with increased PF4 release. In TMA patients exposed to heparin and with refractory or rapidly recurrent thrombocytopenia HIT should always be considered as a possible cause.

Increased von Willebrand factor over decreased ADAMTS-13 activity is associated with poor prognosis in patients with advanced non-small-cell lung cancer

BACKGROUND

Hypercoagulability induced by the imbalance between von Willebrand factor (VWF) secretion and its cleaving protease (ADAMTS-13) has been correlated with cancer metastasis. The aim of this study was to explore the prognostic significance of the VWF/ADAMTS-13 ratio in advanced non-small-cell lung cancer (NSCLC).

METHODS

Pre-treatment sera/plasma levels of VWF, ADAMTS-13, VWF/ADAMTS-13 ratio, factor (F) VIII, and other clinical/laboratory parameters were measured in 119 patients with advanced NSCLC and 102 healthy controls. All patients were followed up to determine the predictive value of these parameters for prognosis of advanced NSCLC.

RESULTS

Elevated VWF, VWF/ADAMTS-13 ratio, and reduced ADAMTS-13 were significantly correlated with the stage and grade of advanced NSCLC and the final status of disease (P<.05). VWF levels and the VWF/ADAMTS-13 ratio were also associated with response to chemotherapy (P<.05). Multivariate analysis identified the VWF/ADAMTS-13 ratio and D-dimer as significant independent predictors of patient mortality. The area under the curve showed that the VWF/ADAMTS-13 ratio was more useful than VWF, ADAMTS-13, and D-dimer to predict mortality. Kaplan-Meier analysis showed that a low VWF/ADAMTS-13 ratio was significantly predictive of improved survival (P=.004).

CONCLUSION

These results suggest that the imbalance between VWF secretion and ADAMTS-13 may play a critical role in the hypercoagulability state in advanced NSCLC. Moreover, elevation of the plasma VWF/ADAMTS-13 ratio may serve as an independent predictive factor for mortality in patients with advanced NSCLC.

Thrombotic thrombocytopenic purpura: pathogenesis, diagnosis and potential novel therapeutics

Thrombotic thrombocytopenic purpura (TTP), a potentially fatal clinical syndrome, is primarily caused by autoantibodies against the von Willebrand factor (VWF)-cleaving metalloprotease ADAMTS-13. In general, severe deficiency of plasma ADAMTS-13 activity (< 10 IU dL-1 ) with or without detectable inhibitory autoantibodies against ADAMTS-13 supports the diagnosis of TTP. A patient usually presents with thrombocytopenia and microangiopathic hemolytic anemia (i.e. schistocytes, elevated serum lactate dehydrogenase, decreased hemoglobin and haptoglobin) without other known etiologies that cause thrombotic microangiopathy (TMA). Normal to moderately reduced plasma ADAMTS-13 activity (> 10 IU dL-1 ) in a similar clinical context supports an alternative diagnosis such as atypical hemolytic uremic syndrome (aHUS) or other types of TMA. Prompt differentiation of TTP from other causes of TMA is crucial for the initiation of an appropriate therapy to reduce morbidity and mortality. Although plasma infusion is often sufficient for prophylaxis or treatment of hereditary TTP due to ADAMTS-13 mutations, daily therapeutic plasma exchange remains the initial treatment of choice for acquired TTP with demonstrable autoantibodies. Immunomodulatory therapies, including corticosteroids, rituximab, vincristine, cyclosporine, cyclophosphamide and splenectomy, etc., should be considered to eliminate autoantibodies for a sustained remission. Other emerging therapeutic modalities, including recombinant ADAMTS-13, adeno-associated virus (AAV) 8-mediated gene therapy, platelet-delivered ADAMTS-13, and antagonists targeting the interaction between platelet glycoprotein 1b and VWF are under investigation. This review highlights the recent progress in our understanding of the pathogenesis and diagnosis of, and current and potential novel therapies for, hereditary and acquired TTP.

Cancer-associated thrombotic microangiopathy

Cancer-associated thrombotic microangiopathy refers to a group of disorders characterised by microvascular thrombosis, thrombocytopenia, and ischaemic end-organ damage. Haemolytic uraemic syndrome and thrombotic thrombocytopenic purpura are the two major subtypes. It can be a manifestation of the malignancy itself or a complication of its therapy. The addition of several new drugs to the therapeutic armamentarium of cancer has brought to light several novel causative factors of this hitherto uncommon complication. This review covers the aetiology, pathogenesis, clinical manifestations, complications, and the management of cancer-associated thrombotic microangiopathy. Careful review of the patient’s medical records coupled with the correlation of clinical findings and laboratory reports can help clinch the diagnosis and institute appropriate treatment on time.

Microangiopathic hemolytic anemia associated with metastatic breast cancer: case report and literature review

INTRODUCTION

Microangiopathic hemolytic anemia (MAHA) is a mechanical hemolytic anemia characterized by the emergence of fragmented red cells in peripheral blood. Here, we report a case of breast cancer associated with cancer-related (CR)-MAHA along with a literature review.

CASE DESCRIPTION

The patient was a 54-year-old woman who made an emergency visit to our hospital because of low back pain, shoulder pain, visual impairment, and anemia. She was diagnosed with stage IV, ER-positive, PgR-positive, HER2-negative left breast cancer (invasive lobular carcinoma), with left axillary adenopathy, metastasis to the soft tissue of the orbital region, multiple bone metastases, pleural dissemination, and metastasis to the stomach and para-aortic lymph nodes. Chemotherapy was initiated successfully; tumor marker levels normalized and the visceral metastases almost disappeared. Hormone therapy was administered for maintenance. Two and a half years later, rapid elevation in tumor marker levels and severe anemia were noted, and fragmented red cells and poikilocytes emerged in the peripheral blood. Positron emission tomography-computed tomography and bone scintigraphy revealed multiple bone metastases, but no evidence of visceral metastasis. CR-MAHA associated with multiple bone metastases was diagnosed, and Paclitaxel chemotherapy was initiated with frequent blood transfusions. Her anemia gradually improved, with a decrease in tumor marker levels and the number of blood transfusions. Three months later, tumor marker levels increased again. Because the anemia was also exacerbated, chemotherapy was changed to eribulin. Tumor marker levels temporally decreased, and the anemia tended to improve, but 3 months later, the levels were elevated again and the anemia was exacerbated. A switch to another regimen was planned, but best supportive care was chosen instead because of rapid deterioration of liver function. The patient died a month later.

DISCUSSION AND EVALUATION

CR-MAHA is thought to have a different pathologic mechanism from TTP or HUS. Although CR-MAHA is a clinical condition associated with a very poor prognosis, we consider it controllable for long period by rapid introduction of chemotherapy in many cases.

CONCLUSIONS

CR-MAHA is a nearly oncologic emergency that medical oncologists need to be able to recognize even though it rarely occurs in breast cancer.

Thrombotic microangiopathy, cancer, and cancer drugs

Thrombotic microangiopathy (TMA) is a complication that can develop directly from certain malignancies, but more often results from anticancer therapy. Currently, the incidence of cancer drug-induced TMA during the last few decades is >15%, primarily due to the introduction of anti-vascular endothelial growth factor (VEGF) agents. It is important for clinicians to understand the potential causes of cancer drug-induced TMA to facilitate successful diagnosis and treatment. In general, cancer drug-induced TMA can be classified into 2 types. Type I cancer drug-induced TMA includes chemotherapy regimens (ie, mitomycin C) that can potentially promote long-term kidney injury, as well as increased morbidity and mortality. Type II cancer drug-induced TMA includes anti-VEGF agents that are not typically associated with cumulative dose-dependent cell damage. In addition, functional recovery of kidney function often occurs after drug interruption, assuming a type I agent was not given prior to or during therapy. There are no randomized controlled trials to provide physician guidance in the management of TMA. However, previously accumulated information and research suggest that endothelial cell damage has an underlying immunologic basis. Based on this, the emerging trend includes the use of immunosuppressive agents if a refractory or relapsing clinical course that does not respond to plasmapheresis and steroids is observed.

Pulmonary tumor thrombotic microangiopathy: report of 3 cases and review of the literature

Pulmonary tumor thrombotic microangiopathy (PTTM) is a rare clinical entity where tumor cell embolisms in pulmonary circulation induce thrombotic microangiopathy (TMA), respiratory failure, and subacute cor pulmonale.We describe 3 cases of PTTM that presented as the initial manifestation of metastatic gastric adenocarcinoma with TMA and pulmonary infiltrates.All 3 cases had similar clinical and laboratory features, which included moderate thrombocytopenia without renal failure, hemolysis with extremely high serum lactate dehydrogenase levels, leukoerythroblastosis in peripheral blood smear, altered coagulation tests, lymphadenopathies, and interstitial pulmonary infiltrates. All patients died within 2 weeks of diagnosis. Two cases were initially misdiagnosed as idiopathic thrombotic thrombocytopenic purpura and treated with plasma exchange with no response. One patient had bone marrow infiltration by malignant cells. Autopsies revealed PTTM associated with gastric disseminated adenocarcinoma (signet-ring cell type in 2 patients and poorly differentiated type in 1).PTTM should be considered in the differential diagnosis of patients with fulminant microangiopathic hemolytic anemia, such as atypical thrombotic thrombocytopenic purpura, mainly those with pulmonary infiltrates, disseminated intravascular coagulation, or Trousseau syndrome.

ADAMTS-13 in the Diagnosis and Management of Thrombotic Microangiopathies

Thrombotic microangiopathies (TMAs) comprise a group of distinct disorders characterized by microangiopathic hemolytic anemia, thrombocytopenia, and microvascular thrombosis. For many years distinction between these TMAs, especially between thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS), remained purely clinical and hard to make. Recent discoveries shed light on different pathogenesis of TTP and HUS. Ultra-large von Willebrand factor (UL-VWF) platelet thrombi, resulting from the deficiency of cleavage protease which is now known as ADAMTS-13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13), were found to cause TTP pathology, while Shiga toxins or abnormalities in regulation of the complement system cause microangiopathy and thrombosis in HUS. TMAs may appear in various conditions such as pregnancy, inflammation, malignancy, or exposure to drugs. These conditions might cause acquired TTP, HUS, or other TMAs, or might be a trigger in individuals with genetic predisposition to ADAMTS-13 or complement factor H deficiency. Differentiation between these TMAs is highly important for urgent initiation of appropriate therapy. Measurement of ADAMTS-13 activity and anti-ADAMTS-13 antibody levels may advance this differentiation resulting in accurate diagnosis. Additionally, assessment of ADAMTS-13 levels can be a tool for monitoring treatment efficacy and relapse risk, allowing consideration of therapy addition or change. In the past few years, great improvements in ADAMTS-13 assays have been made, and tests with increased sensitivity, specificity, reproducibility, and shorter turnaround time are now available. These new assays enable ADAMTS-13 measurement in routine clinical diagnostic laboratories, which may ultimately result in improvement of TMA management.

Hemolytic anemia and metastatic carcinoma: case report and literature review

Hemolytic anemia can complicate the development of a variety of solid tumors and hematologic malignancies. Although patients may have an established diagnosis with documented metastases, microangiopathic hemolytic anemia (MAHA) can be a presenting feature of an occult malignancy. Prompt diagnosis is essential because conditions that mimic the symptoms of MAHA, including thrombotic thrombocytopenic purpura, have different prognoses and therapeutic options. Although the exact pathogenesis is not yet delineated, we present herein a case of cancer-associated MAHA and discuss the known pathways that can contribute to the initiation and propagation of hemolytic anemia in patients with cancer. The patient is a 69-year-old woman with breast carcinoma that had metastasized to her rectum, urinary bladder, and brain. She eventually developed progressive decline in her functional status, with intermittent epistaxis and melena. The results of laboratory studies revealed hemolytic anemia and thrombocytopenia; results of a bone-marrow biopsy confirmed the involvement by metastatic carcinoma. The patient received red blood cell and platelet transfusions and was discharged to hospice care after clinical stabilization. She died soon thereafter.

Nephrotic syndrome associated with tyrosine kinase inhibitors for pediatric malignancy: case series and review of the literature

BACKGROUND

Tyrosine kinase (TK) inhibitors are increasingly being used to treat a variety of pediatric malignancies. Reports in adult patients describe a range of effects of TK inhibitors on the kidney, including hypertension, proteinuria, acute kidney injury, and thrombotic microangiopathy (TMA); however, there are only a few reports of TK-inhibitor-associated nephrotic syndrome.

METHODS

We report four pediatric patients with various malignancies (chronic myelogenous leukemia, acute lymphoblastic leukemia, and glioma/renal cell carcinoma) who developed nephrotic syndrome during treatment with TK inhibitors (imatinib, sunitinib, dasatinib, and quizartinib). One of the four patients also had clinical features of TMA.

RESULTS

Three of the four patients achieved complete remission of nephrotic syndrome with discontinuation of the TK inhibitor and have had no additional nephrotic syndrome relapses to date. The temporal relationship of nephrotic syndrome onset to TK-inhibitor therapy and resolution of nephrotic syndrome with cessation of therapy strongly imply an association in these patients.

CONCLUSIONS

TK inhibitors are important therapies in pediatric cancer, and their use is expanding. Nephrotic syndrome with or without features of TMA is a potential complication of these therapies in children.

Gallbladder cancer-associated thrombotic microangiopathy

Cancer-associated thrombotic microangiopathy (TMA) is a rare but serious condition seen in patients diagnosed with malignancy. Certain tumor characteristics highlight this entity, such as large tumor burden, adenocarcinoma histology with mucinous features and bone marrow infiltration. Although these tumors may originate from any site, the majority are of stomach, breast or prostate origin. The optimal therapy is unknown but there is evidence that immediate initiation of an effective antineoplastic regimen is important. However, it is difficult to differentiate cancer-associated TMA from primary thrombotic thrombocytopenic purpura in a timely manner. We present the first case of cancer-associated TMA in a patient secondary to a locally advanced gallbladder adenocarcinoma that lacked mucinous features and bone marrow involvement. The clinical presentation closely mimicked primary thrombocytopenic purpura and led to the ineffective use of plasma exchange. Nonetheless, the patient eventually received systemic chemotherapy and had a remarkable response by the resolution of her TMA.

Cancer-related microangiopathic hemolytic anemia: clinical and laboratory features in 168 reported cases

Cancer-related microangiopathic hemolytic anemia (CR-MAHA) is a paraneoplastic syndrome characterized by Coombs-negative hemolytic anemia with schistocytes and thrombocytopenia. We reviewed and analyzed all cases of CR-MAHA reported since 1979 (the time of the last published review on this topic) according to predefined criteria. We found 154 cases associated with solid cancer and 14 with lymphoma. Among the solid cancers, gastric, breast, prostate, lung, and cancer of unknown primary (CUP) were most common; 91.8% of cancers were metastatic, and in 19.4% of solid cancers CR-MAHA did not occur until recurrence of cancer. Lymphoma cases included Hodgkin disease, angiotropic lymphoma, diffuse large cell lymphoma, and myeloma. Evaluation of the clinical and laboratory findings revealed that only a minority of cases presented with the features of thrombotic thrombocytopenic purpura (TTP) or atypical hemolytic uremic syndrome (aHUS), with the exception of prostate cancer, where aHUS was a common presentation. Compared to hereditary or immune TTP or aHUS, disseminated intravascular coagulation and pulmonary symptoms were more common in CR-MAHA. Plasma exchange or fresh frozen plasma was rarely effective except in prostate cancer patients with aHUS. CR-MAHA responded to antitumor therapy in many patients with gastric, breast, lung, and CUP cancers. These patients had a superior survival compared to patients without chemotherapy. Compared to the prognosis of patients with metastatic cancer without CR-MAHA, the prognosis of CR-MAHA patients was greatly inferior. There is evidence that some cases of CR-MAHA in lymphoma are immune mediated.

Breast Cancer-Associated Thrombotic Microangiopathy

BACKGROUND: Thrombotic microangiopathy (TMA) is defined as thrombocytopenia and microangiopathic hemolytic anemia. Cancer-associated TMA, a rare but fatal condition, seems an entity distinct from classical thrombotic thrombocytopenic purpura (TTP)/hemolytic uremic syndrome (HUS). PATIENTS AND METHODS: All patients with breast cancer-associated TMA treated at our institution between 2003 and 2008 were analyzed retrospectively. To elucidate pathophysiological mechanisms, we measured the serum activity of the metalloprotease ADAMTS13. RESULTS: 8 patients were identified. All showed bone marrow infiltration of breast cancer as well as thrombocytopenia, schistocytes, and hemolytic anemia. ADAMTS13 activity was mildly decreased in 4/6 patients (20-108%, normal range 30-120%), but none showed severely low levels as is characteristic of classical TTP. 6 patients were treated with anthracycline-containing fractionated chemotherapy, 5/6 patients experienced partial response. Overall survival was 13 months. Fractionated chemotherapy was well tolerated. CONCLUSIONS: Cancer-associated TMA has an underlying mechanism different from classical TTP. While bone marrow infiltration might be of major relevance, ADAMTS13 deficiency seems to be an epiphenomenon. Fractionated chemotherapy resulted in higher remission rates and comparatively long survival.

A report of disseminated adenocarcinoma presenting as thrombotic thrombocytopenic purpura

Thrombotic microangiopathies (TMAs) represent a heterogeneous group of diseases characterized by a microangiopathic hemolytic anemia, peripheral thrombocytopenia, and organ failure of variable severity. TMAs encompass thrombotic thrombocytopenic purpura (TTP), typically characterized by fever, central nervous system manifestations and hemolytic uremic syndrome (HUS), in which renal failure is the prominent abnormality. In patients with cancer TMAs may be related to various antineoplastic drugs or to the malignant disease itself. The reported series of patients with TMAs directly related to cancer are usually heterogeneous, retrospective, and encompass patients with hematologic malignancies with solid tumors or receiving chemotherapy, each of which may have distinct presentations and pathophysiological mechanisms. Patients with disseminated malignancy who present with microangiopathic hemolytic anemia and thrombocytopenia may be misdiagnosed as thrombotic thrombocytopenic purpura (TTP) Only a few cases of TTP secondary to metastatic adenocarcinoma are known in the literature. We present a case of a 34-year-old man with TTP syndrome secondary to metastatic small-bowel adenocarcinoma. Patients with disseminated malignancy had a longer duration of symptoms, more frequent presence of respiratory symptoms, higher lactate dehydrogenase levels, and more often failed to respond to plasma exchange treatment. A search for systemic malignancy, including a bone marrow biopsy, is appropriate when patients with TTP have atypical clinical features or fail to respond to plasma exchange.

Novel recombinant glycosylphosphatidylinositol (GPI)-anchored ADAMTS13 and variants for assessment of anti-ADAMTS13 autoantibodies in patients with thrombotic thrombocytopenic purpura

Immunoglobulin Gs (IgGs) against ADAMTS13 are major causes of acquired (idiopathic) thrombotic thrombocytopenic purpura (TTP). We report here a novel cell-based assay using glycosylphosphatidylinositol (GPI)-anchored ADAMTS13 or variants expressed on cell membrane for assessment of autoantibodies in patients with TTP. We showed that IgGs from all 26 patients with acquired TTP bound to cells expressing a GPI anchored full-length ADAMTS13 (gFL) and a variant truncated after the spacer domain (gS). Also, IgGs from 25/26 (96.7%) of these TTP patients bound to cells expressing a GPI-anchored C-terminal fragment, TSP1 2-8 plus CUB (gT2C). In contrast, none of the 20 healthy blood donors showed detectable binding of their IgGs to the cells expressing gFL, gS, and gT2C. A moderate, but statistically significant correlation was observed between plasma concentrations of anti-ADAMTS13 IgG and positive cells expressing gFL (r=0.65), gS (r=0.67), and gT2C (r=0.42). These results suggest that the microtiter-plate assay and the cell-based assay may detect differential antigenic epitopes. Moreover, antigens clustered on cell membranes may enhance antibody binding affinity, thereby increasing analytical sensitivity. Finally, our assay was able to determine kinetic changes of plasma levels of anti-ADAMTS13 IgGs in TTP patients during plasma therapy. Together, our findings suggest that the novel cell-based assay may be applicable for rapid identification and mapping of anti-ADAMTS13 autoantibodies in patients with acquired TTP.

Analyses of data of patients with Thrombotic Microangiopathy in the WAA registry

Thrombotic Microangiopathy (TMA) is a histopathological feature of various diseases including thrombotic thrombocytopenic purpura and hemolytic uremic syndrome. The aim of this study was to investigate the outcome and prognostic variables of TMA-patients.

MATERIALS AND METHODS

Data were consecutively retrieved from the WAA-apheresis registry (www.waa-registry.org) during 2003-2009. Included were all 120 patients (1237 procedures) who suffered from various forms of TMA, as registered by the ICD-10 code M31.1. Besides registry data, more extensive information was retrieved from the latest 64 patients. Adverse events of the TMA patients were compared to those of the other patients in the registry.

RESULTS

The mean age was 46 years (range 11-85 years, 57% women). In 72% therapeutic apheresis was due to an acute indication while a long-term indication was present in 28%. Plasma exchange was performed by centrifugation and filtration technique (95% and 4%, respectively), and immunoadsorption in 1% of the patients. Only fresh frozen plasma was used as replacement fluid in 69% of procedures. Adverse events were more frequent than in the general apheresis population (10% versus 5%, RR 1.9, CI 1.6-2.3). No death occurred due to apheresis treatment. Three percent of the procedures were interrupted. Bronchospasm and/or anaphylactic shock were present in two patients and one patient suffered from TRALI. At admission 26% were bedridden and needed to be fed. The risk of dying during the treatment period was significantly higher if the patient also suffered from a compromising disease, such as cancer. There was an inverse correlation between the ADAMTS13 level and the antibody titer (r=-0.47, p=0.034).

CONCLUSIONS

Patients with TMA have an increased risk for moderate and severe AE compared to the general apheresis population. Many patients were severely ill at admission. The prognosis is worse if the patient also has a severe chronic disease. Even slightly increased ADAMTS13-antibody titers seem to have a negative impact on the ADAMTS13 levels.

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.

Cancer-associated microangiopathic hemolytic anemia with thrombocytopenia: an important diagnostic consideration

BACKGROUND

Early initiation of plasma exchange (PE) allows more than 80% of patients with idiopathic thrombotic thrombocytopenic purpura (TTP), most commonly because of severe ADAMTS13 deficiency, to achieve remission and mandates urgency in diagnosis and therapy. Metastatic cancer may present with a microangiopathic hemolytic anemia with thrombocytopenia that is clinically similar to TTP but does not respond to PE. ADAMTS13 activity can be diagnostic but usually not immediately available. Recognition of cancer-associated microangiopathic hemolytic anemia with thrombocytopenia (CA-MHA) is paramount to avoid inappropriate PE therapy and delays in cancer-specific chemotherapy.

OBJECTIVE

To identify distinguishing characteristics of CA-MHA and TTP to facilitate early recognition of CA-MHA.

METHODS

In a retrospective cohort study, baseline clinical and laboratory data of consecutive adult patients with CA-MHA (n = 7) or autoimmune TTP (n = 7) from a registry of patients with clinically suspected acute TTP referred for PE were compared.

RESULTS

The frequencies of bone pain and respiratory symptoms were significantly greater among patients with CA-MHA compared to patients with TTP; other baseline clinical and laboratory characteristics did not differ significantly between the two groups. Response to PE and mortality at day 30 were significantly worse for CA-MHA (14% and 71%, respectively) compared to patients with TTP (86% and 14%, respectively).

CONCLUSIONS

Baseline clinical and laboratory characteristics largely do not distinguish acute CA-MHA from autoimmune acute TTP. While all suspected acute patients TTP should receive urgent PE, bone pain, respiratory symptoms, or inadequate PE response should prompt an early search for CA-MHA.

Cancer awareness in atypical thrombotic microangiopathies

OBJECTIVE

To specify the clinical and biological characteristics of thrombotic microangiopathies (TMAs) associated with a recent diagnosis of cancer. PATIENTS AND Methods. Multicenter study involving 14 national centers. Cross-sectional analysis of 20 patients with cancer-associated TMAs included in our national registry from October 2000 to July 2007. Patients were also compared with 134 adult patients with an acquired idiopathic TMA by univariate analysis.

RESULTS

Patients with a cancer-associated TMA typically displayed severe weight loss, dyspnea, bone pain, as well as disseminated intravascular coagulopathy and massive erythromyelemia (75%, 55%, 50%, 41%, and 85% of cases, respectively). By contrast, these features were observed with a much lower incidence in patients with an idiopathic TMA (8.9%, 19.7%, 0.8%, 7.1%, and 17.5%, respectively). Moreover, median platelet count was higher (48 x 10(9)/l; range, 21-73 x 10(9)/l versus 19 x 10(9)/l; range, 10-38 x 10(9)/l, respectively) and median serum creatinine level was lower (74 microM [range, 68-102] versus 113 microM [range, 80-225], respectively). The activity of the specific von Willebrand factor-cleaving proteinase ADAMTS13 was detectable in 14/17 studied patients. Platelet count improvement was observed in only seven patients and paralleled the response to chemotherapy. Prognosis of patients with cancer-associated TMAs was very poor, with a 30-day and 2-year mortality rate of 50% and 95%, respectively.

CONCLUSION

Cancer-associated TMAs display specific features at onset that should prompt investigation of an underlying disseminated malignancy. In this context, chemotherapy rather than plasma is mandatory since TMA prognosis parallels that of cancer.

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.

Pathogenesis of thrombotic microangiopathies

Profound thrombocytopenia and microangiopathic hemolytic anemia characterize thrombotic microangiopathy, which includes two major disorders: thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS). TTP has at least three types: congenital or familial, idiopathic, and nonidiopathic. The congenital and idiopathic TTP syndromes are caused primarily by deficiency of ADAMTS13, owing to mutations in the ADAMTS13 gene or autoantibodies that inhibit ADAMTS13 activity. HUS is similar to TTP, but is associated with acute renal failure. Diarrhea-associated HUS accounts for more than 90% of cases and is usually caused by infection with Shiga-toxin-producing Escherichia coli (O157:H7). Diarrhea-negative HUS is associated with complement dysregulation in up to 50% of cases, caused by mutations in complement factor H, membrane cofactor protein, factor I or factor B, or by autoantibodies against factor H. The incomplete penetrance of mutations in either ADAMTS13 or complement regulatory genes suggests that precipitating events or triggers may be required to cause thrombotic microangiopathy in many patients.

The thrombotic microangiopathies

The term thrombotic microangiopathy (TMA) encompasses a group of conditions that are defined by, or result from, a similar histopathological lesion. Hemolytic uremic syndrome (HUS), thrombotic thrombocytopenic purpura (TTP), and several other conditions are associated with TMA. Distinguishing HUS from TTP is not always possible unless there are specific causes, such as Shiga toxin, Streptococcus pneumoniae, or a specific molecular defect such as factor H or ADAMTS13 deficiency. This review describes the forms of HUS/TTP that are not related to Shiga toxin, pneumococcal infection, genetic causes, or ADAMTS13 deficiency. Conditions include HUS/TTP associated with autoimmune disorders, human immunodeficiency virus (HIV) infection, transplantation, malignancy, and medications.

Thrombotic thrombocytopenic purpura: a thrombotic disorder caused by ADAMTS13 deficiency

A serious disorder with characteristic microvascular thrombosis involving the brain and other organs, thrombotic thrombocytopenic purpura (TTP) typically presents with thrombocytopenia, hemolysis with schistocytes on blood smears, and mental changes or seizures. It may progress rapidly to a fatal end if the patient is not treated immediately with plasma. Recent advances have shown that TTP is caused by deficiency of a circulating, von Willebrand factor cleaving metalloprotease, ADAMTS13. This new knowledge will provide clues to improve the diagnosis and management of this intriguing disease.

Management of cancer-associated thrombotic microangiopathy: what is the right approach?

A 49-year-old Caucasian woman presented with features suggestive of thrombotic microangiopathy (TMA). She did not respond to treatment with repeated plasma exchange and corticosteroids. A bone marrow biopsy revealed presence of metastatic carcinoma. A limited autopsy revealed presence of breast cancer with rib metastases. Though severe deficiency of von Willebrand factor-cleaving protease was initially proposed as a key pathogenetic factor for thrombotic thrombocytopenic purpura, subsequent studies involving patients with cancer-associated TMA did not find as severe a deficiency of von Willebrand factor-cleaving protease as is seen in idiopathic cases of thrombotic thrombocytopenic purpura. Here we address one approach of management of these patients with cancer-associated TMA.

Disseminated malignancy misdiagnosed as thrombotic thrombocytopenic purpura: A report of 10 patients and a systematic review of published cases

BACKGROUND

Patients with disseminated malignancy who present with microangiopathic hemolytic anemia and thrombocytopenia may be misdiagnosed as thrombotic thrombocytopenic purpura (TTP), resulting in inappropriate plasma exchange treatment, a procedure with major risk, and delay of appropriate chemotherapy.

PURPOSE

To assess clinical features that may distinguish occult disseminated malignancy from TTP.

PATIENTS AND METHODS

We report the 17-year experience of The Oklahoma TTP-Hemolytic-Uremic Syndrome (HUS) Registry (1989-2005) and a systematic review of previously published case reports.

RESULTS

Ten of 351 patients in the Oklahoma Registry who were initially diagnosed with TTP and treated with plasma exchange were subsequently discovered to have disseminated malignancy. Only one patient had a history of cancer. In these 10 patients, neurologic abnormalities, hematocrit, platelet count, and serum creatinine were not different from the 133 concurrent patients with idiopathic TTP. Patients with disseminated malignancy had a longer duration of symptoms, more frequent presence of respiratory symptoms, higher lactate dehydrogenase levels, and more often failed to respond to plasma exchange treatment. Diagnosis of malignancy was made by bone marrow biopsy in six patients but not until autopsy in two patients. A systematic literature review identified 19 additional patients, reported from 1965 to 2005, in whom TTP or HUS was initially suspected and systemic malignancy was subsequently discovered. Fourteen different malignant disorders were diagnosed in these 29 patients.

CONCLUSIONS

Occult disseminated malignancy may mimic TTP. A search for systemic malignancy, including a bone marrow biopsy, is appropriate when patients with TTP have atypical clinical features or fail to respond to plasma exchange.

[Acquired idiopathic thrombotic thrombocytopenic purpura: arguments for an autoimmune disease]

Thrombotic thrombocytopenic purpura (TTP) is a severe form of thrombotic microangiopathy (TMA) characterized by systemic platelet clumping, hemolytic anemia, and multiorgan failure. TTP results from a defect in ADAMTS13, a plasma enzyme specifically involved in the cleavage of highly hemostatic unusually large (UL) von Willebrand factor (vWF) multimers into smaller and less adhesive vWF forms. Failure to degrade these UL-vWF multimers leads to excessive platelet aggregation and capillary occlusion. ADAMTS13 deficiency is related to mutations of the encoding gene in hereditary TTP, whereas in acquired forms it results from autoantibodies that may alter the protein function. This latter finding strongly suggests that acquired idiopathic TTP corresponds to an autoimmune disease. Acquired idiopathic TTP appears to be associated with clinical features suggestive of autoimmunity in one third of cases. In two thirds, autoantibodies such as antinuclear antibodies may be observed. This review, based on an analysis of the literature and on French experience with TMA, focuses on the different autoimmune manifestations that may be observed in TTP, as well as the putative pathophysiological link between autoimmune manifestations and TTP.

Successful Treatment of Primitive Neuroectodermal Tumor-associated Microangiopathy with Multiple Bone Metastases

We report here a 16-year-old male with primitive neuroectodermal tumor (PNET)-associated probable microangiopathy with multiple bone metastases. Laboratory findings excluded the possibility of amegakaryocytic or immune thrombocytopenia and/or disseminated intravascular coagulation. He was first treated with plasma-exchange (PE), followed by platelet transfusions, steroid pulse therapy and combined chemotherapy. PE and steroid pulse therapy reduced his plasma CRP level. Combined chemotherapy drastically increased his platelet count until it had almost normalized without further transfusion. The plasma level of von Willebrand factor-cleaving protease (ADAMTS13) activity measured before PE was not severely deficient (48% of normal) and an unusually large von Willebrand factor multimer (UL-VWFM) was detected. We consider that this therapeutic strategy has the following benefits: (1) reduction of plasma levels of factors that are harmful to both platelet activation and endothelial cell injury; and (2) the safe transfusion of platelet concentrate in thrombotic microangiopathy. This strategy should be confirmed in further cases.

Treatment of thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP), characterized by thrombocytopenia and microangiopathic haemolytic anaemia, was almost universally fatal until the introduction of plasma exchange (PE) therapy in the 1970s. Based on clinical studies, daily PE has become the first-choice therapy since 1991. Recent findings may explain its effectiveness, which may include, in particular, the removal of anti-ADAMTS13 autoantibodies and unusually large von Willebrand factor multimers and/or supply of ADAMTS13 in acquired idiopathic or congenital TTP. Based on currently available data, the favoured PE regimen is daily PE [involving replacement of 1-1.5 times the patient's plasma volume with fresh-frozen plasma (FFP)] until remission. Adverse events of treatment are mainly related to central venous catheters. The potential reduction of plasma related side-effects, such as transfusion-related acute lung injury (TRALI) or febrile transfusion reactions by use of solvent-detergent treated (S/D) plasma instead of FFP is not established by controlled clinical studies. Uncontrolled clinical observations and the hypothesis of an autoimmune process in a significant part of the patients with acquired idiopathic TTP suggest a beneficial effect of adjunctive therapy with corticosteroids. Other immunosuppressive treatments are not tested in controlled trials and should be reserved for refractory or relapsing disease. There is no convincing evidence for the use of antiplatelet agents. Supportive treatment with transfusion of red blood cells or platelets has to be evaluated on a clinical basis, but the transfusion trigger for platelets should be very restrictive. Further controlled, prospective studies should consider the different pathophysiological features of thrombotic microangiopathies, address the prognostic significance of ADAMTS13 and explore alternative exchange fluids to FFP, the role of immunosuppressive therapies and of new plasma saving approaches as recombinant ADAMTS13 and protein A immunoadsorption.

Thrombotic thrombocytopenic purpura

This overview summarizes the history of thrombotic thrombocytopenic purpura (TTP) from its initial recognition in 1924 as a most often fatal disease to the discovery in 1997 of ADAMTS-13 deficiency as a major risk factor for acute disease manifestation. The cloning of the metalloprotease, ADAMTS-13, an essential regulator of the extremely adhesive unusually large von Willebrand factor (VWF) multimers secreted by endothelial cells, as well as ADAMTS-13 structure and function are reviewed. The complex, initially devised assays for ADAMTS-13 activity and the possible limitations of static in vitro assays are described. A new, simple assay using a recombinant 73-amino acid VWF peptide as substrate will hopefully be useful. Hereditary TTP caused by homozygous or double heterozygous ADAMTS-13 mutations and the nature of the mutations so far identified are discussed. Recognition of this condition by clinicians is of utmost importance, because it can be easily treated and--if untreated--frequently results in death. Acquired TTP is often but not always associated with severe, autoantibody-mediated ADAMTS-13 deficiency. The pathogenesis of cases without severe deficiency of the VWF-cleaving protease remains unknown, affected patients cannot be distinguished clinically from those with severely decreased ADAMTS-13 activity. Survivors of acute TTP, especially those with autoantibody-induced ADAMTS-13 deficiency, are at a high risk for relapse, as are patients with hereditary TTP. Patients with thrombotic microangiopathies (TMA) associated with hematopoietic stem cell transplantation, neo-plasia and several drugs, usually have normal or only moderately reduced ADAMTS-13 activity, with the exception of ticlopidine-induced TMA. Diarrhea-positive-hemolytic uremic syndrome (D+ HUS), mainly occurring in children is due to enterohemorrhagic Escherichia coli infection, and cases with atypical, D- HUS may be associated with factor H abnormalities. Treatment of acquired idiopathic TTP involves plasma exchange with fresh frozen plasma (FFP), and probably immunosuppression with corticosteroids is indicated. We believe that, at present, patients without severe acquired ADAMTS-13 deficiency should be treated with plasma exchange as well, until better strategies become available. Constitutional TTP can be treated by simple FFP infusion that rapidly reverses acute disease and--given prophylactically every 2-3 weeks--prevents relapses. There remains a large research agenda to improve diagnosis of TMA, gain further insight into the pathophysiology of the various TMA and to improve and possibly tailor the management of affected patients.

Radiographically occult, diffuse intrasinusoidal hepatic metastases from primary breast carcinomas: a clinicopathologic study of 3 autopsy cases

CONTEXT

Liver metastases usually present as radiographically detectable mass lesions that do not significantly compromise liver function. Rarely, metastatic carcinoma can diffusely infiltrate hepatic sinusoids, a pattern of metastasis that may be missed on imaging studies, and can result in liver failure.

OBJECTIVE

To describe the clinicopathologic features of 3 cases of diffuse intrasinusoidal hepatic metastases from primary breast carcinomas identified at autopsy.

DESIGN

Clinical histories and radiographic, macroscopic, and microscopic appearances of the livers were compared. Sampled liver tissue was stained with antibodies to E-cadherin, smooth muscle actin, and CD44.

RESULTS

Two of 3 cases had a history of infiltrating ductal carcinoma of the breast and presented with new-onset liver failure, but no hepatic metastases were identified on radiologic imaging. An additional case had no history of carcinoma, presented with a severe thrombocytopenic thrombotic purpura-like syndrome, and metastatic carcinoma of the breast was diagnosed only at autopsy. The livers in all 3 cases at autopsy were homogeneous, firm, and tan-yellow, and contained no large metastatic lesions. Microscopically, poorly differentiated carcinoma diffusely infiltrated hepatic sinusoids. Antibodies to smooth muscle actin stained activated hepatic stellate cells lining involved sinusoids. Cell surface adhesion molecules, E-cadherin or CD44, were not detected in any hepatic metastases.

CONCLUSION

Diffuse intrasinusoidal hepatic metastases of breast carcinoma can occupy a large percentage of the hepatic volume, yet remain occult both radiographically and macroscopically. This type of metastatic spread can present as cryptogenic liver failure. The 3 cases we studied were associated with an absence of E-cadherin and CD44 expression.

Plasma therapy in thrombotic thrombocytopenic purpura: review of the literature and the Bern experience in a subgroup of patients with severe acquired ADAMTS-13 deficiency

Based on clinical studies daily plasma exchange (PE) has become the first-choice therapy for thrombotic thrombocytopenic purpura (TTP) since 1991. Recent findings may explain its effectiveness, which particularly may include supply of ADAMTS-13 and removal of anti-ADAMTS-13 autoantibodies and unusually large von Willebrand factor (VWF) multimers. The most preferable PE regimens as well as replacement fluids are discussed and treatment-related adverse reactions are summarized. Proposals for a potential reduction of their frequency and for improvement of treatment efficiency are given. These suggestions are partially based on the experience of our institution in adult patients with severe ADAMTS-13 deficiency (<5% activity), and include (1) continuous calcium-gluconate infusion during PE in order to reduce citrate-related adverse reactions; (2) the evaluation of solvent/detergent-treated (S/D) plasma as replacement fluid in order to reduce adverse events due to fresh frozen plasma (FFP); (3) the evaluation of immunoadsorption in order to increase procedural efficiency in autoantibody removal; and (4) the substitution of ADAMTS-13 by means of recombinant drug instead of plasma.

Measurement of von Willebrand factor-cleaving protease (ADAMTS-13) activity in plasma: a multicenter comparison of different assay methods

A severely deficient ADAMTS-13 activity (<5%) is a key laboratory finding confirming the diagnosis of thrombotic thrombocytopenic purpura (TTP), whereas a mildly or moderately decreased activity is found in various other conditions. Laboratory tests for ADAMTS-13 activity must reliably identify a severe deficiency and detect inhibitory antibodies against ADAMTS-13. We carried out a multicenter comparison of different assays for ADAMTS-13 activity in plasma, including the quantitative immunoblotting of degraded von Willebrand factor (VWF) substrate, the residual collagen binding activity and ristocetin cofactor activity of degraded VWF, and an immunoradiometric assay. The main goal was to investigate whether all assays concordantly identified severe ADAMTS-13 deficiency and detected inhibitory antibodies. ADAMTS-13 activity was determined by five laboratories in 30 plasma samples of patients with hereditary and acquired TTP and other conditions. ADAMTS-13 activity values of the samples ranged from <3% to > 100%. Concerning the identification of a severe ADAMTS-13 deficiency, good interassay and interlaboratory agreement was observed with only one false-negative and two false-positive results by two laboratories using a collagen binding assay. For samples with normal or mildly to moderately reduced ADAMTS-13 activity, results were less concordant. There was good agreement for the detection of strong inhibitors. We conclude that all assays investigated are useful as a screening test in suspected TTP. Further assay improvement is needed, however.

Platelets: thrombotic thrombocytopenic purpura

Abnormalities of plasma von Willebrand factor (VWF) have been recognized to be associated with thrombotic thrombocytopenic purpura (TTP) for over 20 years. Patients with chronic, relapsing TTP have VWF multimers that are larger than normal, similar in size to those secreted by cultured endothelial cells. Recent observations have documented that a deficiency of a VWF-cleaving protease (termed ADAMTS13) may be responsible for the presence of these unusually large VWF multimers. Multiple mutations of the ADAMTS13 gene can result in ADAMTS13 deficiency and cause congenital TTP; autoantibodies neutralizing ADAMTS13 protease activity have been associated with acquired TTP. In Section I, Dr. Evan Sadler reviews the structure, biosynthesis, and function of the ADAMTS13 protease. He describes the mutations that have been identified in congenital TTP and describes the relationship of ADAMTS13 deficiency to the development of both congenital and acquired TTP. Dr. Sadler postulates that the development of TTP may be favored by conditions that combine increased VWF secretion, such as during the later stages of pregnancy, and decreased ADAMTS13 activity. In Section II, Dr. Bernhard Lämmle describes the assay methods for determining ADAMTS13 activity. Understanding the complexity of these methods is essential for understanding the difficulty of assay performance and the interpretation of assay data. Dr. Lämmle describes his extensive experience measuring ADAMTS13 activity in patients with TTP as well as patients with acute thrombocytopenia and severe illnesses not diagnosed as TTP. His data suggest that a severe deficiency of ADAMTS13 activity (< 5%) is a specific feature of TTP. However, he emphasizes that, although severe ADAMTS13 deficiency may be specific for TTP, it may not be sensitive enough to identify all patients who may be appropriately diagnosed as TTP and who may respond to plasma exchange treatment. In Section III, Dr. James George describes the evaluation and management of patients with clinically suspected TTP, as well as adults who may be described as having hemolytic-uremic syndrome (HUS). Dr. George presents a classification of TTP and HUS in children and adults. Appropriate evaluation and management are related to the clinical setting in which the diagnosis is considered. A clinical approach is described for patients in whom the diagnosis of TTP or HUS is considered (1) following bone marrow transplantation, (2) during pregnancy or the postpartum period, (3) in association with drugs which may cause TTP either by an acute immune-mediated toxicity or a dose-related toxicity, (4) following a prodrome of bloody diarrhea, (5) in patients with autoimmune disorders, and (6) in patients with no apparent associated condition who may be considered to have idiopathic TTP. Patients with idiopathic TTP appear to have the greatest frequency of ADAMTS13 deficiency and appear to be at greatest risk for a prolonged clinical course and subsequent relapse. Management with plasma exchange has a high risk of complications. Indications for additional immunosuppressive therapy are described.

Presence of ADAMTS13 activity in a patient with metastatic cancer and thrombotic microangiopathy

Patients with metastatic cancers occasionally present with microangiopathic hemolysis and thrombocytopenia. A patient with metastatic adenocarcinoma of the colon and microangiopathic hemolysis was treated with plasma exchange for a presumptive diagnosis of thrombotic thrombocytopenic purpura (TTP). However, her condition continued to deteriorate and a determination of ADAMTS13 activity revealed that she did not have TTP. Despite similarity in clinical manifestation, microangiopathic hemolysis in patients with metastatic cancers may not be caused by ADAMTS13 deficiency and the role of plasma exchange in such patients should be reevaluated.