RT Book, Section
A1 Wolgast, Lucia R.
A1 Rand, Jacob H.
A2 Kaushansky, Kenneth
A2 Prchal, Josef T.
A2 Burns, Linda J.
A2 Lichtman, Marshall A.
A2 Levi, Marcel
A2 Linch, David C.
SR Print(0)
ID 1178756416
T1 The Antiphospholipid Syndrome
T2 Williams Hematology, 10e
YR 2021
FD 2021
PB McGraw-Hill Education
PP New York, NY
SN 9781260464122
LK hemonc.mhmedical.com/content.aspx?aid=1178756416
RD 2024/04/18
AB SUMMARYThe  antiphospholipid  (aPL)  syndrome  (APS)  is  an  acquired  thrombophilic  disorder  that  is  identified  by  the  concurrence  of  vascular  thrombosis  and/or  pregnancy  complications  with  laboratory  evidence  for  the  presence  of  autoantibodies  against  phospholipid-associated  proteins  in  blood.  The  main  antigenic  targets  for  thrombogenic  aPL  antibodies  are  epitopes  on  phospholipid-binding  proteins,  the  most  important  of  which  is  β2-glycoprotein  I  (β2GPI).  The  pathophysiologic  basis  of  the  disorder  has  not  yet  been  established;  the  currently  proposed  mechanisms  are  reviewed  in  this  chapter.  The  syndrome  is  identified  by  immunoassays  for  antibodies  against  phospholipid–protein  cofactor  complexes  and  by  coagulation  assays  (“lupus  anticoagulant  assays”)  that  report  the  inhibition  of  phospholipid-dependent  coagulation  reactions  in  vitro.  Testing  should  be  limited  to  individuals  with  clinical  manifestations  of  the  disorder  or  with  a  history  for  systemic  lupus  erythematosus  (in  which  a  high  proportion  of  patients  have  aPL  antibodies).  With  rare  exceptions,  other  patients  should  not  undergo  diagnostic  screening  for  aPL  antibodies  and,  if  tested  and  found  to  be  positive,  should  not  be  committed  to  antithrombotic  therapy  solely  on  the  basis  of  laboratory  abnormalities.Although  any  portion  of  the  circulatory  tree  can  be  affected,  the  deep  veins  of  the  lower  extremities  are  the  most  frequently  targeted.  Patients  with  APS  may  present  with  several  other  abnormalities,  referred  to  as  “noncriteria  manifestations,”  such  as  additional  autoimmune  disorders,  immune  thrombocytopenia,  acquired  platelet  function  abnormalities,  hypoprothrombinemia,  acquired  inhibitors  of  coagulation  factors,  livedo  reticularis,  cardiac  valve  abnormalities,  atherosclerosis,  pulmonary  hypertension,  and  migraine.  Rare  patients  present  with  a  catastrophic  form  of  APS  (CAPS)  in  which  there  is  disseminated  thrombosis  in  large-  and  small-vessel  thrombi,  often  occurring  after  an  infection  or  surgery.  Long-term  warfarin  anticoagulant  therapy  is  the  usual  treatment  for  thrombosis  in  patients  with  APS;  treatment  with  direct  oral  anticoagulants  is  currently  discouraged  because  they  have  been  associated  with  an  increased  risk  of  arterial  thrombotic  events.  Patients  with  recurrent  spontaneous  pregnancy  losses  attributed  to  APS  are  generally  treated  with  aspirin  and  heparin  during  their  pregnancies  through  the  postpartum  period.  Patients  with  CAPS  have  a  high  mortality  rate  and,  in  addition  to  anticoagulants,  often  require  plasmapheresis  and  immunosuppressive  agents;  patients  refractory  to  these  treatments  have  been  reported  to  respond  to  complement  C5  inhibitors.