TdT-positive acute leukemia with monocytoid characteristics: clinical,
cytochemical, cytogenetic, and immunologic findings
J Cuttner, S Seremetis, V Najfeld, A Dimitriu-Bona and RA Winchester
Thirteen patients with acute leukemias that were difficult to classify by
the use of cytochemical staining and terminal deoxyribonucleotidyl
transferase (TdT) activity are reported. The phenotype of the leukemic
cells was characterized by the presence of mature or early monocyte lineage
antigens and intense Ia antigen expression detected by monoclonal
antibodies, terminal deoxytransferase activity, and cytochemical features,
including both Sudan black B and periodic acid- Schiff activity. The mean
age of this group of patients was 60 years. Five patients had leukemia
occurring after chemotherapy or radiotherapy of a prior malignant disease,
and two patients had a refractory anemia prior to development of acute
leukemia. These patients had a low response rate to chemotherapy. This
series of leukemia appears to form a distinct nosologic entity,
representing a leukemic transformation among early cells of the monocyte
lineage, resulting in a predominant neoplastic cell that is less mature
than either the French-American- British M4 acute myelomonocytic leukemia
or M5 acute monoblastic leukemia. The presence of terminal deoxytransferase
activity was interpreted as indicating the primitive state of the cells in
the differentiation sequence, rather than as implying any significance with
respect to lineage.
Volume 64,
Issue 1,
pp. 237-243,
07/01/1984
Copyright © 1984 by The American Society of Hematology
