pure red cell anemia ( prca ) is a syndrome characterized by severe normocytic anemia , reticulocytopenia , and an absence of erythroblasts from an otherwise normal bone marrow .
the acquired form of prca may present as a primary hematologic disorder in the absence of any other diseases , or secondary to various underlying diseases including parvovirus b19 infection , large granular lymphocyte ( lgl ) leukemia and other lymphoproliferative disorders , thymoma , autoimmune disease , the use of offensive drugs , and allogeneic hematopoietic stem cell transplantation ( hsct ) .
previously , prca following allogeneic hsct has been reported in patients after abo - incompatible allogeneic hsct . here
, we describe the first case of prca , to our knowledge , following major abo - compatible allogeneic hsct for acute lymphoblastic leukemia ( all ) resolving completely after rituximab treatment .
a 49-year - old woman with all underwent hla - matched related allogeneic hsct ( containing 2.2  10 cd34 cells / kg ) on december 23 , 2009
. there were no major abo - mismatch blood types between the donor ( o ) and the recipient ( o ) .
the duration from transplantation to an absolute neutrophil count > 0.5  10/l and to a platelet count > 20  10/l was 14 and 17 days .
engraftment was confirmed by a bone marrow aspirate and biopsy on day + 23 . on day + 265 , she showed elevated aspartate transaminase ( ast ) and alanine transaminase ( alt ) , and chronic graft - versus - host disease ( gvhd ) was confirmed by a liver biopsy .
the prednisolone and mycophenolate mofetil were subsequently tapered to 5 and 500 mg on day + 452 .
there was no regular requirement of packed red cell ( prc ) until then . on day + 475 ,
the patient 's hemoglobin level suddenly decreased from 10.3 g / dl to 6.7 g / dl .
we started erythropoietin treatment ( darbepoetin - a 120 g once weekly ) on day + 492 , but there was no improvement in her anemia .
a bone marrow biopsy was performed on day + 545 and revealed a decreased erythroid series without abnormal findings of other cell components , showing a consistent finding of prca .
in addition , we checked for parvovirus b19 and cytomegalovirus , and there was no evidence of viral infections .
we started rituximab 375 mg / m once weekly for four weeks starting on day + 566 . on day + 587 , hemoglobin and reticulocyte began to rise from 6.7 g / dl and 0.4% ( 12,000/l ) to 9.6 g / dl and 4.44% ( 150,500/l ) ( fig .
currently ( on day + 732 ) , the patient has no transfusion requirement and her hemoglobin level has remained as high as 13.2 g / dl .
prca following allogeneic hsct has been mostly reported in situations involving major abo incompatibility between donor and recipient [ 3 , 4 ] , with the exception of one case following major abo - matched allogeneic hsct .
prca following abo - incompatible allogeneic hsct is associated with an interaction of recipient anti - a or anti - b isoagglutinins with donor erythroid precursors expressing a and/or b antigens .
spontaneous remission has been noted but treatments such as plasma exchange , donor - derived leukocyte infusion , erythropoietin , and steroids may be necessary to avoid rbc transfusion and to decrease the risk of hemochromatosis [ 7 , 8 , 9 , 10 , 11 ] .
the mechanism of prca following major abo - matched allogeneic hsct is unclear . in the case report by roychowdhury and linker ,
it is speculated that immune - mediated etiology such as the adoptive transfer of autoimmunity or antibodies to erythroid progenitors resulted in prca .
in addition , non - abo antigens may be involved in prca following allogeneic hsct .
our case was analyzed following allogeneic hsct between a major abo - matched donor - recipient pair .
rituximab is a humanized , murine , monoclonal antibody directed against the cd20 antigen , expressed on pre - b lymphocytes and on mature b lymphocytes .
rituximab has been showed to be highly effective for immune - mediated prca , autoimmune cytopenias , and prca following abo - incompatible allogeneic hsct [ 13 , 14 , 15 ] .
after the third anti - cd20 monoclonal antibody infusion , the patient exhibited a striking rise in her reticulocyte count , and then had a progressive increase in her hemoglobin level .
to our knowledge , this is the first report of rituximab use for the treatment of prca following major abo - matched allogeneic hsct .
rituximab seems to be a promising therapeutic option for patients with prca following abo - matched and abo - mismatched allogeneic hsct .
 pure red cell aplasia ( prca ) following allogeneic hematopoietic stem cell transplantation ( hsct ) has been mostly reported in situations involving major abo incompatibility between donor and recipient . 
 conventional treatments such as plasma exchange , erythropoietin , and steroid are often unsatisfactory . 
 rituximab has been reported to be highly effective for prca following major abo - incompatible allogeneic hsct . 
 a 49-year - old woman with prca following abo - matched allogeneic hsct for acute lymphoblastic leukemia , refractory to erythropoietin treatment , received 4 doses of rituximab 375 mg / m2 weekly . after the 3rd dose of rituximab , she exhibited a striking rise in her reticulocyte count with an increase in her hemoglobin level . 
 to our knowledge , this is the first case of prca following major abo - compatible allogeneic hsct resolving completely after rituximab treatment . 
Introduction
Case Report
Discussion
Disclosure Statement