Persistence of abnormal RBC and platelet phenotype during recovery from aplastic anemia.

Sixteen adults with chronic acquired aplastic anemia had abnormally large RBCs and abnormally small platelets before chemotherapy. During their therapy, transfusion initially obscured these macrocytic RBCs. In the eight who had erythropoietic recovery, endogenous RBCs again were macrocytic, and platelets remained small whether or not the platelet count increased. The percentage of cells containing hemoglobin F changed in only one of the eight subjects. In contrast, the eight who did not have erythropoietic recovery had no reappearance of macrocytes. Of 19 other previously treated patients whose hemoglobin level had recovered to normal for seven to 196 months, 16 had increased mean corpuscular volume (101 to 133 femtoliters) and abnormally small platelets. We conclude that in aplastic anemia the appearance of macrocytes reliably and easily predicts RBC recovery. Furthermore, even in treated, apparently recovered subjects, an abnormality of blood cell size remains.