Abstract
Decreased or absent expression of blood group antigens is well known to occur in acute leukemia. In some carcinomas, the malignant solid tumor cells have also been shown to lose normal blood group antigen expression. In both carcinoma and hematologic malignancies, these findings have been associated with a more aggressive behavior of the neoplasm. A 34-year-old, group AB, Rh positive woman was diagnosed with a preleukemic condition, myelodysplastic syndrome, in December 1988. In April 1989 B antigen expression was markedly decreased, then absent; in November 1989 the patient had progressed to acute leukemia. In April 1990 neither A nor B antigens could be detected, there was disease progression, and the patient died 19 days after A and B antigens were undetectable. Decreased expression of normal blood group antigens may prove useful in differentiating benign from malignant conditions and may indicate a more grave prognosis. Immunohematology 1991;7:89–93.