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Natural killer lymphocyte blast crisis of chronic myelogenous leukemia
M J Warzynski1, C White, M G Golightly
1Immunology Laboratory, Baystate Medical Center, Springfield, Massachusetts 01199.
Insights
This case report details a chronic myelogenous leukemia (CML) patient experiencing a rare blast crisis of natural killer (NK) lymphocytes. Treatment with vincristine and prednisone was initially successful, but the disease later transformed.
Area of Science:
- Hematology
- Immunology
- Oncology
Background:
- Chronic myelogenous leukemia (CML) typically involves myeloid progenitor cells.
- Blast crisis in CML signifies advanced disease, usually with myeloid or lymphoid blasts.
- Natural killer (NK) lymphocytes are crucial for innate immunity and cancer surveillance.
Observation:
- A CML patient presented with a blast crisis characterized by natural killer (NK) lymphocytes.
- Many blasts displayed large granular lymphocytic (LGL) morphology.
- Immunophenotyping confirmed NK lymphocyte lineage (CD45, NKH1, CD2, LEU 17, CD16 positive; CD3, CD8, LEU 7 negative).
Findings:
- Flow cytometry revealed expression of CD11b and CD11c on some NK blasts, markers associated with certain NK cell subsets.
- A portion of cells (approximately 10%) were in the S phase of the cell cycle.
- The NK blasts lacked in vitro functional activity against K562 target cells, consistent with immature NK leukemias.
Implications:
- This unusual NK lymphocyte blast crisis was responsive to vincristine and prednisone therapy.
- The patient eventually relapsed with transformation to progenitor stem cells.
- Flow cytometric immunophenotyping was critical for accurate diagnosis, therapeutic guidance, and patient monitoring.
Abstract:
We describe for the first time a case report documenting a chronic myelogenous leukemia (CML) patient who developed a blast crisis of natural killer (NK) lymphocytes. Many of the blasts exhibited large granular lymphocytic (LGL) morphology. Single parameter immunophenotyping results determined that the granulated as well as the agranulated blast cells were NK lymphocytes (CD45, NKH1, CD2, LEU 17, and CD16 positive; CD3, CD8, and LEU 7 negative). Dual parameter flow cytometric testing also determined that some of the blasts expressed the CD11b and CD11c markers as reported for some types of NK lymphocytes. Approximately 10% of the cells were in the S phase of the cell cycle as determined by a modified Vindelov DNA content analysis test and may theoretically reflect some of those cells expressing CD11b and CD11c. The cells did not express in vitro NK lymphocyte functional activity against a K562 target and therefore similar to other reported cases of presumably immature NK lymphocytic leukemias. The NK lymphocyte blast crisis was successfully treated with vincristine and prednisone. The patient's disease eventually relapsed and transformed to a progenitor stem cell before she died (CD45, 13, CD38, and CD34 positive). The flow cytometric immunophenotyping results contributed significantly as an important adjunct in determining the appropriate diagnosis, helping to select the type of therapy, and monitoring the patient with this unusual type of blast crisis.