Abstract

Acute hybrid leukemia is an uncommon disease that demonstrates malignant transformation expressing lymphoid and myeloid cell lineage. We experienced a case of 25-year-old man with acute leukemia with unusual characteristics: unclassifiable morphology and undifferentiated cytochemistry by French-American-British (FAB) criteria. Microscopically, it disclosed monotonous tumor cell population in lymph node with vascular plugging and perivascular infiltration, and indian file appearance in capsule and surroun ng adipose tissue. Results of flow cytometry and immunohistochemical studies of frozen sections, cytospins, and formalin fixed lymphoid tissues disclosed hybrid form characterized by myeloid and lymphoid cell lineage. The immunophenotype analysis showed both anti-T cell, anti-B cell and anti-myeloid cell monoclonal antibody reactivity; blast cells were consistently CD7+(94.6%), CD13+(97.1%), and CD19+(85.22%). The normal hematopoietic cells were almost replaced by tumor cells in PB and bone marrow. In preparation of cytospin of peripheral blood(PB) cells separated by a Ficoll-hypaque gradients, blast cells were negative for Sudan black B, myeloperoxidase, periodic acid Schiff, and nonspecific esterase.

• Keywords: Hybrid leukemia;Lymphoma;Flow cytometry;Immunohistochemistry;