Objective:

To report a pediatric case of a patient initially diagnosed with de novo Philadelphia chromosome-positive T-lymphoblastic leukemia (T-ALL) who later developed chronic myeloid leukemia (CML) after discontinuing treatment.

Approach:

• Method: label
• Method: text

Key Findings:

• The patient was initially diagnosed with de novo Ph-positive T-ALL based on clinical and cytogenetic findings.
• After discontinuing imatinib treatment for 18 months, the patient developed CML.
• The case highlights the diagnostic challenge in distinguishing between de novo Ph-positive T-ALL and T-lymphoid blast-phase CML.

Interpretation:

The subsequent development of CML suggests that the initial presentation may have represented T-lymphoid BP-CML rather than de novo Ph-positive T-ALL, emphasizing the importance of sustained TKI therapy.

Limitations:

• The case is based on a single patient, limiting generalizability.
• Lack of long-term follow-up data post-treatment discontinuation.

Conclusion:

Accurate classification between de novo Ph-positive T-ALL and T-lymphoid BP-CML is crucial for therapeutic decision-making and long-term management.