RT Book, Section
A1 Segel, George B.
A1 Lichtman, Marshall A.
A2 Kaushansky, Kenneth
A2 Lichtman, Marshall A.
A2 Prchal, Josef T.
A2 Levi, Marcel M.
A2 Press, Oliver W.
A2 Burns, Linda J.
A2 Caligiuri, Michael
SR Print(0)
ID 1147670881
T1 Aplastic Anemia: Acquired and Inherited
T2 Williams Hematology, 9e
YR 2015
FD 2015
PB McGraw-Hill Education
PP New York, NY
SN 9780071833004
LK accessmedicine.mhmedical.com/content.aspx?aid=1147670881
RD 2024/04/23
AB SUMMARYAcquired  aplastic  anemia  is  a  clinical  syndrome  in  which  there  is  a  deficiency  of  red  cells,  neutrophils,  monocytes,  and  platelets  in  the  blood,  and  fatty  replacement  of  the  marrow  with  a  near  absence  of  hematopoietic  precursor  cells.  Reticulocytopenia  is  a  constant  feature.  Neutropenia,  monocytopenia,  and  thrombocytopenia,  when  severe,  are  life-threatening  because  of  the  risk  of  infection  and  bleeding,  complicated  by  severe  anemia.  Most  cases  occur  without  an  evident  precipitating  cause  and  are  caused  by  autoreactive  cytotoxic  T  lymphocytes  that  suppress  or  destroy  primitive  CD34+  multipotential  hematopoietic  cells.  The  disorder  also  can  occur  after  (1)  prolonged  high-dose  exposure  to  certain  toxic  chemicals  (e.g.,  benzene),  (2)  after  specific  viral  infections  (e.g.,  Epstein-Barr  virus),  (3)  as  an  idiosyncratic  response  to  certain  pharmaceuticals  (e.g.,  ticlopidine,  chloramphenicol),  (4)  as  a  feature  of  a  connective  tissue  or  autoimmune  disorder  (e.g.,  lupus  erythematosus),  or,  (5)  rarely,  in  association  with  pregnancy.  The  final  common  pathway  may  be  through  cytotoxic  T-cell  autoreactivity,  whether  idiopathic  or  associated  with  an  inciting  agent  since  they  all  respond  in  a  similar  fashion  to  immunosuppressive  therapy.  The  differential  diagnosis  of  acquired  aplastic  anemia  includes  a  hypoplastic  marrow  that  can  accompany  paroxysmal  nocturnal  hemoglobinuria  or  hypoplastic  oligoblastic  (myelodysplastic  syndrome)  or  polyblastic  myelogenous  leukemia.  Allogeneic  hematopoietic  stem  cell  transplantation  is  curative  in  approximately  80  percent  of  younger  patients  with  high-resolution  human  leukocyte  antigen–matched  sibling  donors,  although  the  posttransplant  period  may  be  complicated  by  severe  graft-versus-host  disease.  The  disease  may  be  significantly  ameliorated  or  occasionally  cured  by  immunotherapy,  especially  a  regimen  coupling  antithymocyte  globulin  with  cyclosporine.  However,  after  successful  treatment  with  immunosuppressive  agents,  the  disease  may  relapse  or  evolve  into  a  clonal  myeloid  disorder,  such  as  paroxysmal  nocturnal  hemoglobinuria,  a  clonal  cytopenia,  or  oligoblastic  or  polyblastic  myelogenous  leukemia.  Several  uncommon  inherited  disorders,  including  Fanconi  anemia,  Shwachman-Diamond  syndrome,  dyskeratosis  congenita  and  others  have  as  a  primary  manifestation  aplastic  hematopoiesis.