血栓性血小板低下性紫斑症：一種紅斑性狼瘡病人不常見但致命性的併發症

Thrombotic thrombocytopenic purpura: an uncommon but fatal complication in patients with systemic lupus erythematosus

目的：研究紅斑性狼瘡病人合併血栓性血小板低下性紫斑症的臨床表徵、腎臟病理學徵象、預後及造成死亡的危險因子。方法：回溯性地研究自西元2004年1月至2008年12月間台中榮總12位紅斑性狼瘡病人合併血栓性血小板低下性紫斑症的病人，其中有4位病人因急性腎衰竭而接受腎臟切片檢查，所有病人的臨床及病理資料和預後皆被回顧檢視。結果：本醫院紅斑性狼瘡病人出現血栓性血小板低下性紫斑症的發生率為每千人年4.2人。每位病人皆出現微血管病性溶血性貧血、血小板低下及急性腎衰竭（只有1位病人例外）。4位病人的腎臟切片檢查皆出現廣泛性增殖性狼瘡腎炎變化及血栓性微血管病性徵象。所有病人皆接受血漿置換術、高劑量類固醇和癌德星（cyclophosphamide）療法的治療（只有2位病人例外）。治療後，有6位病人的狼瘡腎炎獲得緩解。整體住院中死亡率是33.3%。和存活組比較，死亡組有顯著的補體（C3）低下、較高的紅斑性狼瘡疾病活動性指數（SLEDAI）評分和較高的感染率。結論：對於紅斑性狼瘡病人而言，血栓性血小板低下性紫斑症是一種致命性的併發症，特別是在同時出現有感染症或有較高狼瘡疾病活動性的病人身上。因此，臨床醫師應該警覺血栓性血小板低下性紫斑症的各種表徵，包括微血管病性溶血性貧血、血小板低下、急性腎衰竭、發燒或神經學的異常。

Objective: To investigate the clinical manifestations, renal pathological features, outcome and risk factors for mortality of thrombotic thrombocytopenic purpura (TTP) in systemic lupus erythematosus (SLE) patients. Methods: Twelve SLE patients with TTP were enrolled retrospectively from January 2004 to December 2008 in Taichung Veterans General Hospital. Four of them received renal biopsy for acute renal failure. The clinical-pathological data and prognosis were reviewed. Results: The incidence of TTP in SLE patients in our hospital was 4.2 cases per thousand per year. All patients had evidence of microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and acute renal failure (only one exception). Four patients received renal biopsy which showed diffuse proliferative lupus nephritis and thrombotic microangiopathy (TMA) features. All patients received plasmapheresis, high dose steroids and cyclophosphamide therapy (only two exception). Six patients had remission of lupus nephritis. The in-hospital mortality rate was 33.3%. Compared with the survivors, the deceased had signifi cant lower levels of the complement (C3), higher Systemic Lupus Erythematosus Disease Activity Index (SLEDAI) scores and a higher infection rate. Conclusion: In SLE patients, TTP can be fatal, especially in those with superimposed infection or high disease activity of lupus. Thus clinicians should be alert to the TTP manifestations, including MAHA, thrombocytopenia, acute renal failure, fever or neurological abnormalities.