Objective:

To report a rare case of pediatric chronic myeloid leukemia (CML) presenting solely as isolated thrombocytosis and to highlight the atypical presentation that necessitates early BCR::ABL1 testing in differential diagnosis.

Approach:

• Case Description: A 12-year-old female presented with irregular menstruation and prolonged menstrual periods, leading to a diagnosis of thrombocytosis. Initially misdiagnosed with essential thrombocythemia, she was treated with hydroxyurea and aspirin, which yielded no response, prompting further investigation.

Key Findings:

• The patient was initially misdiagnosed with essential thrombocythemia due to isolated thrombocytosis.
• BCR::ABL1 fusion gene testing was crucial for the correct diagnosis of CML.
• Imatinib therapy led to a significant reduction in platelet counts and a complete cytogenetic response.

Interpretation:

This case illustrates the atypical presentation of CML in children and the necessity for early genetic testing in cases of isolated thrombocytosis.

Limitations:

• The rarity of pediatric CML makes it difficult to generalize findings.
• The limited number of similar cases in literature restricts comprehensive understanding of the condition.

Conclusion:

Early BCR::ABL1 fusion gene assessment is essential for pediatric patients presenting with isolated thrombocytosis to ensure accurate diagnosis and timely treatment.