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[Infant leukemia with t(1;22) presenting proliferation of erythroid and megakaryocytic cell lineages]
M Oshima1, T Fukushima, K Koike
1Department of Pediatrics, Ibaraki Children's Hospital.
Insights
This infant leukemia case shows blasts expressing both red blood cell and platelet precursor markers, suggesting a common origin. This dual marker expression occurred during bone marrow relapse.
Area of Science:
- Hematology
- Pediatric Oncology
- Molecular Biology
Background:
- Infant leukemia presents unique diagnostic challenges.
- Distinguishing between different myeloid leukemia subtypes is crucial for treatment.
- Lineage infidelity in leukemia blasts can complicate diagnosis.
Observation:
- A 9-month-old girl presented with anemia, splenomegaly, and thrombocytopenia.
- Bone marrow examination revealed erythroblasts and megakaryoblasts.
- Flow cytometry showed distinct CD41 and glycophorin A positive populations initially.
Findings:
- At relapse, leukemia blasts became double-positive for erythroblastic and megakaryoblastic surface markers.
- Chromosomal analysis revealed a t(1;22)(p13;q13) translocation, specific for infant acute megakaryoblastic leukemia (M7).
- The findings suggest leukemia originated from a common progenitor cell of both erythroid and megakaryocytic lineages.
Implications:
- This case highlights the potential for lineage plasticity in infant leukemia.
- Understanding progenitor cell abnormalities is key to diagnosing and treating infant myeloid leukemias.
- The t(1;22) translocation serves as a critical diagnostic marker for this specific infant leukemia subtype.
Abstract:
We report a case of infant leukemia with the proliferation of both erythroblast and megakaryoblast lineages. The blasts became double-positive for both erythroblastic and megakaryoblastic surface markers at the time of bone marrow relapse. A 9-month-old girl was admitted to our hospital presenting chiefly poor with weight gain and anemia. She also had splenomegaly, pleural effusion, leukocytosis, and thrombocytopenia. A bone marrow specimen showed 53.2% erythroblasts (PAS positive, alpha-NA positive, CD41 negative, MPO negative) and 20.4% megakaryoblasts with marked cytoplasmic blebs. We examined specimens by two-color flow cytometric analysis. At the onset, CD41+ glycophorin A- fraction and CD41- glycophorin A+ fraction were two major components. At the bone marrow relapse, the majority of blasts had altered to double-positive. Chromosomal analysis showed t (1; 22) (p13; q13), which has been reported to be specific for acute megakaryoblastic leukemia (M7) in infants. We reasoned that a leukemia had occurred in this patient at a progenitor cell level common to both erythroid and megakaryocytic lineages.