A Transient Appearance of CALLA Positive Blastoid Cells after Allogeneic Bone Marrow Transplantation in Patient with Acute Lymphoblastic Leukemia

Abstract

A 26-year-old female patient with acute lymphoblastic leukemia (ALL) (CALLA⁺, TdT⁺, Ia⁺) in the first relapse received an allogeneic bone marrow graft from an HLA identical sister. Engraftment was demonstrated by the blood typing on 35th day after marrow infusion. Five days later, bone marrow aspirate showed marked increase in CALLA positive blastoid cells (approximately 30%). These cells, however, were negative for TdT and were noticed for next 40 days. Thereafter she had a complete remission for 20 months without further chemotherapy. This case suggests that the appearance of CALLA positive blastoid cells in the bone marrow shortly after bone marrow transplantation may play an important role in the recovery of hemopoiesis in bone marrow recipients.