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Philadelphia-chromosome positive essential thrombocythemia. Two cases in children
M B Kastan1, B A Zehnbauer, B G Leventhal
1Division of Pediatric Oncology, Johns Hopkins Hospital, Baltimore, MD 21205.
Insights
Philadelphia chromosome (Ph1)-positive essential thrombocythemia (ET) can occur in children. The presence of the Ph1 chromosome does not exclude an ET diagnosis, and translocation site variations may not impact disease characteristics.
Area of Science:
- Hematology
- Oncology
- Genetics
Background:
- Essential thrombocythemia (ET) is a myeloproliferative neoplasm characterized by elevated platelet counts.
- The Philadelphia chromosome (Ph1), a hallmark of chronic myeloid leukemia, is rarely found in ET.
- Pediatric ET cases are uncommon, and the significance of Ph1 in this population is not well-defined.
Observation:
- Two pediatric patients with essential thrombocythemia (ET) were diagnosed with the presence of the Philadelphia chromosome (Ph1).
- Diagnosis in both cases was confirmed by clinical presentation and marked primary thrombocytosis.
- Analysis revealed different sites of the Ph1 translocation in the two patients, detected using a bcr genomic probe.
Findings:
- The presence of the Philadelphia chromosome (Ph1) should not rule out a diagnosis of essential thrombocythemia (ET).
- Variations in the Ph1 translocation site were observed between the two pediatric cases.
- These findings suggest that the specific translocation site may not be critical in determining cell lineage predominance in Ph1-positive myeloproliferative disorders.
Implications:
- This study expands the understanding of Ph1-positive ET, particularly in pediatric cases.
- It highlights the importance of considering ET even with the presence of the Ph1 chromosome.
- Further research is warranted to explore the prognostic and therapeutic implications of differing Ph1 translocation sites in myeloproliferative neoplasms.
Abstract:
Two cases of children with essential thrombocythemia (ET) with the presence of a Philadelphia chromosome (Ph1) are presented and discussed. Diagnosis was based on their clinical presentation and marked primary thrombocytosis. The site of the Ph1 translocation, as detected by a 1.2-kb bcr genomic probe, differed in the two patients. These cases, along with other reported cases of Ph1-positive ET in the literature, suggest that the presence of the Ph1 cannot be used to rule out a diagnosis of ET. Additionally, the differing translocation sites in these cases suggests that the exact translocation site may not be significant in determining which cell lineage will predominate in a Ph1-positive myeloproliferative disorder.