Department of Emergency and Critical Care Medicine, Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
Department of Internal Medicine, Miyazaki Prefectural Miyazaki Hospital, Miyazaki, Japan.
Am J Case Rep. 2021 Aug 2;22:e932251. doi: 10.12659/AJCR.932251.
BACKGROUND Thrombotic microangiopathy, characterized by microangiopathic hemolytic anemia, thrombocytopenia, and organ damage by microvascular thrombosis, has a high mortality rate; therefore, early diagnosis and treatment are important. Thrombotic thrombocytopenic purpura is caused by a deficiency of a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs 13 (ADAMTS13), and results in thrombotic microangiopathy. Influenza virus causes thrombotic thrombocytopenic purpura by inducing immunoglobulin G autoantibodies against ADAMTS13. We report a rare case of thrombotic thrombocytopenic purpura caused by influenza A without anti-ADAMTS13 antibody that was treated by plasma exchange. CASE REPORT A 57-year-old woman was admitted to our hospital because of hypoxemia. We diagnosed pneumonia and disseminated intravascular coagulation. Despite treatment, she developed thrombocytopenia, and we diagnosed thrombotic microangiopathy and started plasma exchange. With a PLASMIC score of 6 points and neuropsychiatric symptoms, we strongly suspected thrombotic thrombocytopenic purpura and started rituximab. However, ADAMTS13 activity by FRETS-VWF73 assay was 65%, and anti-ADAMTS13 antibody was negative. After 4 plasma exchanges and 2 rounds of rituximab, platelet numbers and lactate dehydrogenase and creatinine concentrations normalized on the 16th day of hospitalization. Subsequently, influenza A (H1N1) was identified in a nasopharyngeal swab collected on admission. Plasma enzyme-linked immunosorbent assay testing for chromogenic ADAMTS13 activity showed a significant decrease (<0.5%). Therefore, we diagnosed thrombotic thrombocytopenic purpura caused by influenza A without anti-ADAMTS13 antibody. CONCLUSIONS We present a rare case of thrombotic thrombocytopenic purpura without anti-ADAMTS13 antibody caused by influenza A virus successfully treated by plasma exchange. Influenza A may reduce ADAMTS13 activity without inducing autoantibodies.
血栓性微血管病的特征为微血管性溶血性贫血、血小板减少症和微血管血栓引起的器官损伤，其死亡率较高，因此早期诊断和治疗很重要。血栓性血小板减少性紫癜是由于缺乏 a disintegrin-like 和金属蛋白酶与血小板反应素 1 型基序 13（ADAMTS13）而引起的，并导致血栓性微血管病。流感病毒通过诱导针对 ADAMTS13 的免疫球蛋白 G 自身抗体引起血栓性血小板减少性紫癜。我们报告了一例罕见的由流感 A 引起的无抗 ADAMTS13 抗体的血栓性血小板减少性紫癜病例，该病例通过血浆置换治疗。
一名 57 岁女性因低氧血症入住我院。我们诊断为肺炎和弥散性血管内凝血。尽管进行了治疗，但她出现血小板减少症，我们诊断为血栓性微血管病并开始进行血浆置换。根据 PLASMIC 评分 6 分和神经精神症状，我们强烈怀疑血栓性血小板减少性紫癜并开始使用利妥昔单抗。然而，FRETS-VWF73 测定的 ADAMTS13 活性为 65%，且抗 ADAMTS13 抗体阴性。在进行了 4 次血浆置换和 2 轮利妥昔单抗治疗后，在入院第 16 天血小板计数、乳酸脱氢酶和肌酐浓度恢复正常。随后，在入院时采集的鼻咽拭子中鉴定出甲型流感（H1N1）。血浆酶联免疫吸附测定法检测显色 ADAMTS13 活性显示显著降低（<0.5%）。因此，我们诊断为甲型流感引起的无抗 ADAMTS13 抗体的血栓性血小板减少性紫癜。
我们报告了一例罕见的由甲型流感病毒引起的无抗 ADAMTS13 抗体的血栓性血小板减少性紫癜成功通过血浆置换治疗的病例。甲型流感可能会降低 ADAMTS13 活性而不诱导自身抗体。
