The significance of lymphocytosis in congenital hypoplastic anemia.

Two infants with congenital hypoplastic anemia had an unusual number of lymphocytes in their peripheral blood and in the bone marrow. This caused an erroneous diagnosis of acute lymphocytic leukemia to be made in the first case and inappropriate therapy to be administered for three months. The second of these cases provided an unusual opportunity to study human erythrocyte precursor dynamics. Serial bone marrow aspirates, obtained after institution of treatment with a corticosteroid, revealed an initial increase in labeled lymphocytes, a concomitant decrease in their number, and the subsequent appearance of erythroid elements. These findings suggest that cells classified morphologically as lymphocytes may serve as erythroid precursors in human beings.