Purpura thrombotique thrombocytopénique acquis auto-immun chez l'enfant : à propos d'1 cas

Long-term remission of recurrent thrombotic thrombocytopenic purpura (TTP) after Rituximab in children and young adults

INTRODUCTION

Acquired thrombotic-thrombocytopenic purpura (TTP) is an autoimmune disorder characterized by autoantibodies directed against the von Willebrand metalloprotease. Depletion of B-cells can prevent synthesis of this antibody and presumably induce remission of the disease. In adults, Rituximab (RTX) was effective in relapsed or refractory acute idiopathic TTP.

PROCEDURE

We report the long-term follow-up of five children and two adolescents (age at diagnosis 6-19 years, median 15 years) who were treated with RTX for recurrent or refractory TTP. Some of the patients suffered from recurrent refractory TTP with long histories of previous unsuccessful treatments. One had TTP associated with pancreatitis.

RESULTS

Three patients have been in complete remission after one treatment course with RTX. Four relapsed after 1 to 5 years, respectively, and responded to additional courses of RTX. One of them is in long-term remission after a third course of RTX and splenectomy. Compared to literature reports with a median follow up of 1.4 years (3-46 month), follow-up of our patients after treatment with RTX was very long (2-12.7 years, median 7.7 years). RTX therapy could induce long-term remissions in children with refractory recurrent TTP. Median duration of remission was longer and relapses per patient-years less frequent in patients receiving RTX compared to patients not receiving it. Remissions were achieved in children within one week, much faster than in adults.

CONCLUSION

Because of the rapid induction of remissions, RTX may be suitable for first-line therapy in pediatric acquired antibody-mediated TTP.

Successful treatment of relapsing autoimmune thrombotic thrombocytopenic purpura with rituximab

Thrombotic thrombocytopenic purpura (TTP) is a rare but life-threatening condition characterized by thrombotic microangiopathy. The standard treatment for TTP is plasmapheresis. For refractory or relapsing cases, various immunosuppressive agents have been tried, and among them rituximab has shown promising results. TTP is rarer in the pediatric age group and the use of rituximab in children with TTP is limited. Reported herein is the successful treatment of relapsing autoimmune TTP with rituximab in a 12-year-old girl.

Children and adults with thrombotic thrombocytopenic purpura associated with severe, acquired Adamts13 deficiency: comparison of incidence, demographic and clinical features

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP) associated with severe, acquired ADAMTS13 deficiency is uncommonly reported in children. The incidence, demographic, and clinical features of these children, compared to adults, have not been described.

PROCEDURES

This study focused on children (<18 years old) and adults with TTP associated with severe, acquired ADAMTS13 deficiency, defined as activity <10%. The incidence rates for TTP in children and adults were calculated from patients enrolled in the Oklahoma TTP-HUS (Hemolytic-Uremic syndrome) Registry, 1996-2012. To describe demographic and clinical features, children with TTP were also identified from a systematic review of published reports and from samples sent to a reference laboratory for analysis of ADAMTS13.

RESULTS

The standardized annual incidence rate of TTP in children was 0.09 × 10(6) children per year, 3% of the incidence rate among adults (2.88 × 10(6) adults per year). Among the 79 children who were identified (one from the Oklahoma Registry, 55 from published reports, 23 from the reference laboratory), TTP appeared to be more common among females, similar to the relative increased frequency of women among adults with TTP, and more common in older children. Clinical data were available on 52 children; the frequency of severe renal failure, relapse, treatment with rituximab, and systemic lupus erythematosus in these children was similar to adults with TTP.

CONCLUSIONS

TTP associated with severe, acquired ADAMTS13 deficiency is uncommon in children. The demographic and clinical features of these children are similar to the features of adults with TTP.

Thrombotic thrombocytopenic purpura in children

PURPOSE OF REVIEW

Thrombotic thrombocytopenic purpura (TTP) is a rare life-threatening disease in children, due to a severe deficiency of ADAMTS13 (a disintegrin and metalloproteinase with thrombospondin type 1 repeats, member 13), inherited in congenital TTP or secondary to anti-ADAMTS13 antibodies in acquired TTP. Rapid techniques for ADAMTS 13 assays, long-term follow-up of patients, phenotype-genotype analysis, improved therapeutic schedules, and new therapies have emerged.

RECENT FINDINGS

Rapid techniques for ADAMTS13 assays now permit rapid confirmation of diagnosis. In congenital TTP, mutations affecting the N-terminal domains of ADAMTS13 are associated with lower residual ADAMTS13 activity and more severe phenotype. Early initiation of plasma infusion treatment and lifelong prophylactic plasma infusion have decreased mortality and sequels and prevent relapses. In acquired TTP, a disease of adolescents but also of children less than 2, adding rituximab to plasma exchange is beneficial. Recombinant ADAMTS13 ought to be soon available for congenital TTP, while acquired TTP children might benefit from its administration, alone or in association with rituximab, to avoid or limit plasma exchange duration.

SUMMARY

Progress in the understanding of TTP has boosted physicians' awareness that diagnosis and treatment are medical emergencies. New therapies hopefully will decrease treatment burden and improve prognosis.

Intravenous Immunoglobulin Therapy When Plasmapheresis Fails in Thrombotic Thrombocytopenic Purpura Associated with Severe ADAMTS 13 Deficiency in Childhood: A Case Report

Thrombotic thrombocytopenic purpura (TTP) is a disorder of the blood-coagulation system, causing extensive microscopic clots to form in the small blood vessels throughout the body. TTP is quite a rare pathology in childhood, being more frequent among adults. Often it is hardly to distinguish from other haematological pathologies in children both for its uncommon incidence and for the presence of clinical forms that are heterogeneous and difficult to classify. We report the case of an 11-year-old girl suffering from TTP, in whom the study of metallo-protease ADAMST 13 showed a low value (<10%) with positive anti-ADAMTS 13 Ig G and inhibitor, strengthening the hypothesis of autoimmune genesis. The girl was initially treated with cycles of plasmapheresis with both poor compliance and benefit for the girl and later treated with IV Immunoglobulin. This last treatment resulted in a rapid improvement of the symptomatology and no reappearance of the clinical signs at four-year follow-up.

Congenital thrombotic thrombocytopenic purpura associated with moyamoya syndrome in a 3-year-old girl: a case report

A 3-year-old girl who presented with anemia, thrombocytopenia, and recurrent strokes is described. The cerebral angiography revealed moyamoya vasculopathy. Her younger brother also had anemia and thrombocytopenia but no neurologic abnormalities. Both children had severe deficiency of ADAMTS13 (A Disintegrin And Metalloprotease with Thrombospondin like domain activity) confirming the diagnosis of congenital thrombotic thrombocytopenic purpura. The children responded well to regular fresh-frozen plasma infusions. This report expands the spectrum of hematologic diseases associated with moyamoya syndrome. Unexplained thrombocytopenia, especially in the presence of neurologic symptoms, should prompt an evaluation for ADAMTS13deficiency. The diagnosis has significant implications not only for therapy but also for genetic counseling.

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

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

Successful treatment with rituximab for acute refractory thrombotic thrombocytopenic purpura related to acquired ADAMTS13 deficiency: a pediatric report and literature review

OBJECTIVE

To report the case of a child with severe autoimmune thrombotic thrombocytopenic purpura (TTP) resistant to plasma exchange and steroids who was successfully treated with rituximab.

DESIGN

Case report and review of the literature on pediatric acquired TTP. The report was approved by an independent local ethics committee.

SETTING

Pediatric intensive care unit in a tertiary care children's hospital.

PATIENT

A 10-yr-old boy was referred to the emergency unit with fever, vomiting, confusion, hemolytic anemia, thrombocytopenia, and mild acute renal failure. An atypical hemolytic uremic syndrome was suspected, and plasma exchange was started urgently. The patient was refractory to plasma therapy and presented critical complications. After a diagnosis of acquired TTP attributable to anti-ADAMTS13 autoantibodies had been made, he was treated with rituximab, which resulted in a stable clinical remission.

INTERVENTIONS

Rituximab therapy.

MEASUREMENTS AND MAIN RESULTS

Clinical remission.

CONCLUSIONS

TTP is a rare but life-threatening condition in children that is characterized by hemolytic anemia, thrombocytopenia, and signs of ischemic organ dysfunction. If renal involvement is present, TTP may be misdiagnosed as hemolytic uremic syndrome, but reliable screening for ADAMTS13 activity and anti-ADAMTS autoantibodies allow us to distinguish the two entities and provide adequate therapy.

Thrombotic thrombocytopenic purpura in childhood

Thrombotic thrombocytopenic purpura (TTP) is a rare disease, especially in childhood, and has a high mortality rate in the absence of appropriate treatment. It is characterised by microangiopathic haemolytic anaemia and consumptive thrombocytopenia. TTP may be difficult to distinguish from haemolytic uraemic syndrome (HUS) because of similar clinical manifestations and laboratory findings. In the past, TTP and HUS have often been considered to represent variable expressions of a single entity. Our increased understanding of the pathogenesis of TTP has in turn resulted in significant improvements in its treatment and outcomes. Several immunomodulating agents are currently being used with variable outcomes.

Rituximab therapy in two children with autoimmune thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a rare disease among pediatric patients, in whom it may be mistaken for hemolytic uremic syndrome (HUS) and idiopathic thrombocytopenic purpura (ITP). Familial forms are caused by mutations in the ADAMTS13 gene, whereas acquired forms may result from an inhibitory antibody directed against ADAMTS13, a metalloprotease that cleaves very large multimers of Von Willebrand factor (VWF), thereby preventing platelet aggregation in blood vessels. We report two cases of TTP. The first was a 15-year-old girl with her first episode of TTP that failed to respond after 10 days of plasmapheresis and was treated with rituximab; she has remained in remission at 12 months of follow-up. The second was a 6-year-old boy with acquired relapsing TTP previously managed with plasmapheresis and prednisolone, who presented with a third relapse that was treated with plasmapheresis and rituximab; he remains in remission 17 months after treatment. Rituximab has been used by pediatricians for treating B cell malignancy, autoimmune diseases and antibody-mediated diseases, such as the Factor VIII inhibitors in hemophilia A, and may also have a promising role in children with acute refractory or chronic relapsing TTP.

Thrombotic thrombocytopenic purpura related to severe ADAMTS13 deficiency in children

Thrombotic thrombocytopenic purpura (TTP) related to a severely deficient activity of the von Willebrand factor cleaving protease, ADAMTS (A Disintegrin And Metalloprotease with ThromboSpondin type 1 repeats) 13, is a life-threatening event, the onset of which may occur as early as childhood. TTP is either inherited (Upshaw-Schulman syndrome) via ADAMTS13 gene mutations (neonatal onset) or acquired via anti-ADAMTS13 autoantibodies (childhood onset). TTP is due to platelet- and von-Willebrand-factor-rich thrombi of the microvasculature, inducing mechanical hemolytic anemia, consumption thrombocytopenia, and multivisceral ischemia. Clinical course consists of relapsing acute events triggered mostly by infections, associated icterus and hyperbilirubinemia, severe hemolytic anemia with schistocytosis and a negative Coombs test, severe thrombocytopenia, and sometimes symptoms related to visceral ischemia (renal failure, central nervous system vascular events, other organ failure). The recently available ADAMTS13 laboratory investigation combining measurement of ADAMTS13 activity in plasma, search for an ADAMTS13 circulating inhibitor, and anti-ADAMTS13 IgG and ADAMTS13 gene sequencing is a crucial addition to TTP diagnosis. Plasma exchanges are first-line treatment of acquired TTP, combined with steroids and immunosuppressive drugs. Curative treatment of acute events in Upshaw-Schulman syndrome relies on plasma infusions (provider of active ADAMTS13). Guidelines for preventive treatment of relapses are not clearly established but should associate plasmatherapy and caution to triggers of relapses. Therapeutic perspectives are focused on the development of concentrated plasma-derived ADAMTS13 or recombinant ADAMTS13.