title: The transient appearance of small blastoid cells in the marrow after bone marrow transplantation.
abstract: Of 14 patients who underwent allogeneic or syngeneic bone marrow transplantation, 6 had a transient appearance of small blastoid cells in the bone marrow after transplantation. Most of these patients (11) had leukemia, although 3 had severe aplastic anemia. The cells were 8-18 micron in diameter and had scant cytoplasm and dense nuclei with smooth, homogeneous chromatin. They often had distinct nuclear clefts. These cells constituted 4.0-21.3% of the total number of bone marrow cells. They were not reactive with peroxidase, alpha-naphtyl butylate esterase, naphthol AS-D chloroacetate esterase, or periodic acid-Schiff stains. Immunocytochemical analysis revealed that the small blastoid cells expressed terminal deoxynucleotidyl transferase, Ia-like, CD19, and CD10 antigens and cytoplasmic mu heavy chains, indicating a precursor B-cell phenotype. CD20 antigen was not expressed on these cells. The data suggest that cytoplasmic mu may be expressed earlier than CD20 antigen in the differentiation of B-cell lineage. The morphologic, cytochemical, and immunophenotypic characteristics did not distinguish these nonneoplastic cells distinctly from leukemic lymphoblastic cells. The increase of small blastoid cells was a transient and self-limited phenomenon, in contrast to that of neoplastic blasts. These cells should be recognized as a common component of the bone marrow of marrow transplant recipients. The significance and role of these cells in immune recovery and hematopoiesis remain uncertain.
authors.affiliation: Division of Clinical Laboratory, Kanagawa Cancer Center, Yokohama, Japan.
authors.forename: S D
authors.initials: SD
authors.lastname: Kobayashi
authors.forename: K
authors.initials: K
authors.lastname: Seki
authors.forename: N
authors.initials: N
authors.lastname: Suwa
authors.forename: C
authors.initials: C
authors.lastname: Koama
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: K
authors.initials: K
authors.lastname: Aiba
authors.forename: A
authors.initials: A
authors.lastname: Maruta
authors.forename: M
authors.initials: M
authors.lastname: Matsuzaki
authors.forename: H
authors.initials: H
authors.lastname: Fukawa
authors.forename: H
authors.initials: H
authors.lastname: Kanamori
mesh_terms: D001853:Bone Marrow / Q000473:pathology*; D016026:Bone Marrow Transplantation; D006801:Humans; D007150:Immunohistochemistry; D016130:Immunophenotyping; D011183:Postoperative Complications; D011184:Postoperative Period; D013194:Staining and Labeling