儿童血栓性血小板减少性紫癜

Thrombotic thrombocytopenic purpura in pediatric patients

摘要:

血栓性血小板减少性紫癜（TTP）在儿童病例中甚为少见，但如未能及时诊断及施予治疗，其后果则极为严重。其最常见之5种病症为：血小板减少、微血管溶血性贫血、急性肾衰竭、发热及中枢神经系统症状。但临床病例中，并不一定会同时出现上述5种症状。故此医疗人员对此病必须有极高之警觉性。TTP之病理特征包括：外周血涂片可见裂体细胞，Coombs 试验阴性，血清乳酸脱氢酶增高及中度或重度血小板减少。TTP发病机理主因缺乏ADAMTS13，从而引发微血管溶血性贫血及血小板减少。TTP可概括分为家族性TTP（Upshaw Schulman 综合征）和继发性TTP。家族性TTP是由于先天性ADAMTS13缺乏所致，其急性治疗法为血浆置换，当病情稳定后，可输注新鲜冰冻血浆以防止病情复发。继发性TTP是指患者因体内产生抗体而导致ADAMTS13功能减退，主要治疗方法亦为血浆置换，最新之临床文献显示rituxiamb对此症亦颇有治疗价值。

Abstract:

Although thrombotic thrombocytopenic purpura (TTP) is rarely seen in pediatric patients, failure to recognize this condition often leads to severe consequences and poor outcomes. Classic features of TTP include thrombocytopenia, microangiopathic hemolytic anemia, acute kidney injury, fever, and central nervous system involvement. However, patients suffering from this condition may not present with all of the symptoms simultaneously. Therefore, it is of utmost importance for healthcare providers to have a high index of suspicion. Laboratory investigations may reveal the presence of schistocytes on peripheral blood smear, negative Coombs test, high lactate dehydrogenase levels and severely low platelet counts. The etiology of TTP is mainly due to insufficient cleavage of the large multimers of von Willebrand factor (vWF) secondary to decreased activity of ADAMTS13 (a disintegrin and metalloprotease with Thrombospondin type 1 repeats, member 13). TTP can be broadly classified into familial TTP (Upshaw Schulman syndrome) and non-familial TTP. Familial TTP is due to a congenital deficiency of ADAMTS13. Its mainstay of therapy is initiation of plasmapheresis during the acute phase, followed by regular fresh frozen plasma (FFP) infusions. Alternatively, non-familial TTP is due to a decrease in ADAMTS13 activity secondary to the presence of anti-ADAMTS13 antibodies. Once again, the primary treatment is plasmapheresis; however, recent anecdotal data also supports the use of rituximab in select cases.