Acquired von Willebrand disease in malignant peripheral neuroectodermal tumor (PNET)

The Intriguing Connections between von Willebrand Factor, ADAMTS13 and Cancer

von Willebrand factor (VWF) is a complex and large protein that is cleaved by ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 motif, member 13), and together they serve important roles in normal hemostasis. Malignancy can result in both a deficiency or excess of VWF, leading to aberrant hemostasis with either increased bleeding or thrombotic complications, as respectively seen with acquired von Willebrand syndrome and cancer-associated venous thromboembolism. There is emerging evidence to suggest VWF also plays a role in inflammation, angiogenesis and tumor biology, and it is likely that VWF promotes tumor metastasis. High VWF levels have been documented in a number of malignancies and in some cases correlate with more advanced disease and poor prognosis. Tumor cells can induce endothelial cells to release VWF and certain tumor cells have the capacity for de novo expression of VWF, leading to a proinflammatory microenvironment that is likely conducive to tumor progression, metastasis and micro-thrombosis. VWF can facilitate tumor cell adhesion to endothelial cells and aids with the recruitment of platelets into the tumor microenvironment, where tumor/platelet aggregates are able to form and facilitate hematogenous spread of cancer. As ADAMTS13 moderates VWF level and activity, it too is potentially involved in the pathophysiology of these events. VWF and ADAMTS13 have been explored as tumor biomarkers for the detection and prognostication of certain malignancies; however, the results are underdeveloped and so currently not utilized for clinical use. Further studies addressing the basic science mechanisms and real word epidemiology are required to better appreciate the intriguing connections between VWF, ADAMTS13 and malignancy. A better understanding of the role VWF and ADAMTS13 play in the promotion and inhibition of cancer and its metastasis will help direct further translational studies to aid with the development of novel cancer prognostic tools and treatment modalities.

Acquired von Willebrand's disease associated with epithelial myoepithelial carcinoma of the parotid salivary gland

This is the first case report of a patient with acquired von Willebrand's disease (AvWD) secondary to epithelial myoepithelial carcinoma (EMC) of the parotid salivary gland. This patient presented to haematology following an abnormal bleeding episode with von Willebrand factor Ristocetin cofactor (VWF:RCo) <5% and VWF:Ag 13%. He was diagnosed with AvWD. At the same time he was found to have a left parotid lump which was excised following a multidisciplinary team meeting. This was histologically reported as an EMC. Following excision, unusually this patient's AvWD did not resolve. Extensive investigation looking for other causes of the AvWD did not reveal any other potential cause; therefore, due to the similar timing of onset of both pathologies it is felt that the AvWD in this case is secondary to the EMC. This case report highlights the presentation, investigation and management of AvWD and parotid lumps as well as discussing proposed pathophysiological mechanisms for AvWD.

Pathophysiology of acquired von Willebrand disease: a concise review

Acquired von Willebrand disease (AVWD) is a rare, underdiagnosed hemorrhagic disorder, which is similar to congenital VWD with regard to the clinical and laboratory parameters; however, it is found in individuals with no positive family history and has no genetic basis. The etiology is varied, the commonest being hematoproliferative disorders and cardiovascular disorders. Other disorders associated with AVWD are autoimmune disorders such as systematic lupus erythematosus, hypothyroidism, and neoplasia, or it may also be drug induced. In quite a few cases, the etiology is unknown. The pathogenic mechanisms are different in different underlying disorders or they may be overlapping among these disorders. Some of the proposed mechanisms include the development of autoantibodies, selective absorption of high molecular weight von Willebrand factor (VWF) multimers, non-selective absorption of VWF, mechanical destruction of VWF under high shear stress, and increased proteolysis. This report presents a concise review of the pathophysiological mechanisms of AVWD in these various underlying conditions.

The Role Of von Willebrand Factor In Hemorrhagic And Thrombotic Disorders

von Willebrand factor (VWF) is a multimeric plasma protein that mediates platelet adhesion as well as platelet aggregation at sites of vascular injury and acts as a carrier of factor VIII. Although acquired or inherited VWF deficiency is associated with a bleeding tendency, there is increasing evidence that VWF has a pivotal role in thrombogenesis. In fact, while the presence in the plasma of unusually large VWF multimers, due to a congenital or acquired deficiency of a VWF-cleaving metalloprotease, has been implicated in the pathogenesis of thrombotic thrombocytopenic purpura, high plasma levels of VWF have been associated with an increased risk of both arterial and venous thrombosis. The role of VWF in normal and pathological hemostasis is discussed in this review, and important advances in the pathophysiology, diagnosis, and treatment of VWF-associated disorders are also described.

Acquired von Willebrand syndrome: an update

Acquired von Willebrand syndrome (aVWS) is a rare bleeding disorder with laboratory findings similar to those for congenital von Willebrand disease (VWD). However, unlike congenital VWD, it arises in individuals with no personal or family history of bleeding. aVWS occurs in association with a variety of underlying disorders, most frequently in lymphoproliferative disorders, myeloproliferative disorders, and cardiovascular diseases. Through an analysis of the more recent literature data, the pathophysiology and the clinical, laboratory, and therapeutic aspects of this syndrome are concisely reported in this review.

Recent acquisitions in acquired and congenital von Willebrand disorders

von Willebrand factor is a multimeric plasma protein that mediates platelet adhesion as well as platelet aggregation at sites of vascular injury and, moreover, acts as a carrier of factor VIII. Its deficiency is associated with a bleeding tendency. The progresses in the pathophysiology, diagnosis and management of inherited von Willebrand disease and acquired von Willebrand syndrome will be discussed in this review.

Correction of intraoperative coagulopathy in a patient with neurofibromatosis type I with intravenous desmopressin (DDAVP)

A patient with the genetic condition neurofibromatosis type I and no known coagulopathy undergoing cesarean delivery, had diffuse uterine and surgical site bleeding that was not correctable by oxytocin, methylergonovine and PGF2 alpha. Despite good uterine tone, hemorrhage continued from the uterus and the surrounding tissues, persisting even after surgical ligation of the uterine arteries. With no change in her condition, which was behaving clinically as a coagulopathy, an infusion of desmopressin acetate (DDAVP) was begun. The patient's bleeding promptly resolved shortly after infusion of this agent. A review of relevant literature suggests that platelet reactivity of patients with neurofibromatosis type 1 is attenuated in some in vitro conditions. Thus, there may be some theoretical basis for using DDAVP in patients with neurofibromatosis type 1 who have bleeding problems with no other known source, such as in the case presented here.

Acquired von Willebrand disease

Acquired von Willebrand disease (AvWD) is a relatively rare acquired bleeding disorder that usually occurs in elderly patients, in whom its recognition may be delayed. Patients usually present predominantly with mucocutaneous bleeding, with no previous history of bleeding abnormalities and no clinically meaningful family history. Various underlying diseases have been associated with AvWD, most commonly hematoproliferative disorders, including monoclonal gammopathies, lymphoproliferative disorders, and myeloproliferative disorders. The pathogenesis of AvWD remains incompletely understood but includes autoantibodies directed against the von Willebrand factor (vWF), leading to a more rapid clearance from the circulation or interference with its function, adsorption of vWF by tumor cells, and nonimmunologic mechanisms of destruction. Laboratory evaluation usually reveals a pattern of prolonged bleeding time and decreased levels of vWF antigen, ristocetin cofactor activity, and factor VIII coagulant activity consistent with a diagnosis of vWD. Acquired vWD is distinguished from the congenital form by age at presentation, absence of a personal and family history of bleeding disorders, and, often, presence of a hematoproliferative or autoimmune disorder. The severity of the bleeding varies considerably among patients. Therapeutic options include desmopressin and certain factor VIII concentrates that also contain vWF. Successful treatment of the associated illness can reverse the clinical and laboratory manifestations. Intravenous immunoglobulins have also shown some efficacy in the management of AvWD, especially cases associated with monoclonal gammopathies. Awareness of AvWD is essential for diagnosis and appropriate management.

Acquired von Willebrand syndromes: clinical features, aetiology, pathophysiology, classification and management

Acquired von Willebrand syndrome (AVWS) associated with hypothyroidism is of type I, results from a decreased synthesis of factor VIII and von Willebrand factor (VWF), responds to desmopressin with normal half-life times for factor VIII and VWF parameters, and disappears after treatment with I-thyroxine. AVWS type I or III, which occurs in a minority of patients with Wilms' tumour in the complete absence of an inhibitor against VWF and no absorption of factor VIII or VWF onto nephroblastoma cells, responds to chemotherapy and/or tumour resection. Hyaluronic acid produced by nephroblastoma cells may be the causative factor in atypical AVWS in Wilms' tumour. AVWS associated with thrombocythaemia of various myeloproliferative disorders is characterized by normal factor VIII and von Willebrand factor antigen (VWF: Ag) levels and a selective deficiency of functional ristocetin co-factor activity (VWF: RCo) and collagen-binding activity (VWF: CBA). AVWS type II in thrombocythaemia is caused by a platelet-dependent proteolysis of large VWF multimers, given the inverse relationship between platelet count and large VWF multimers in plasma and specific increases in the number of proteolytic VWF fragments in plasma. The laboratory findings of AVWS associated with systemic lupus erythematosus or IgG benign monoclonal gammopathy are characterized by a prolonged bleeding time and activated partial thromboplastin time, decreased or absent ristocetin-induced platelet activity, low to very low levels of factor VIII coagulant activity (mean 15%), VWF: Ag (mean 10.7%) and VWF: RCo (mean 6.2%), and a type II multimeric pattern of VWF. Neutralizing and non-neutralizing anti-VWF autoantibodies, usually IgG, have been detected in patient plasma either free or tightly bound to the intermediate and high molecular weight VWF factor VIII particles. The bound auto antibody-antigen complex is rapidly cleared from the circulation, resulting in low levels of factor VIII, VWF parameters as documented by a poor response to desmopressin and VWF factor VIII concentrate. High-dose intravenous immunoglobulin transiently corrects the factor VIII coagulant and VWF levels, lasting for a few weeks in AVWS type II associated with systemic lupus erythematosus or IgG benign monoclonal gammopathy. Prednisolone is effective in AVWS associated with autoimmune disorder. Prednisolone and chemotherapy will not affect AVWS associated with IgG benign monoclonal gammopathy because the monoclonal IgG protein remains to act as an anti-VWF autoantibody. An absorption of VWF to malignant cells has been documented in a few patients with various lymphoproliferative disorders or adrenal carcinoma and suggested to result in a depletion of VWF. The clinical picture of AVWS associated with early-stage IgG multiple myeloma, chronic lymphocytic leukaemia or non-Hodgkin's lymphoma without a paraprotein or no detectable underlying disorder is similar to that of AVWS type II in IgG benign monoclonal gammopathy but poorly documented with regard to the underlying immune mechanism of AVWS. The mechanical destruction of large VWF multimers may be of relevance in conditions in which the shear rate of flowing blood is increased, as may occur in cases of aortic stenosis, other heart valve defects or stenosed vessels. Drug-induced AVWS has been described in association with the use of pesticides valproic acid, ciprofloxacin, griseofulvin, tetracycline, thrombolytic agents and hydroxyethyl starch.

Acquired von Willebrand disease: concise review of occurrence, diagnosis, pathogenesis, and treatment

Acquired von Willebrand disease (AvWD) is a rare complication of an autoimmune or neoplastic disease. It is associated mostly with a lymphoid or plasma cell proliferative disorder. The clinical manifestations are similar to congenital von Willebrand disease. Diagnosis is confirmed by the demonstration of decreased levels of factor VIII coagulant activity (VIII:C), ristocetin cofactor activity (vWF:RCo), and von Willebrand factor (vWF) antigen (vWF:Ag). vWF multimer analysis usually reveals a type II defect with decreased abundance of higher molecular weight vWF multimers. Various pathogenetic mechanisms have been described, including the development of anti-vWF antibodies and adsorption of vWF by tumor cells. Successful management approaches have included treatment of the underlying disorder, infusion of high-dose gamma globulin, replacement therapy with factor VIII/vWF concentrates, intravenous infusion of desmopressin, and administration of corticosteroids.