A 50-year-old man with chronic phase CML well controlled on imatinib suddenly develops fever, bruising, and rising blast count. Marrow now shows 35% myeloblasts. Cytogenetic analysis of the leukemic clone identifies additional chromosomal abnormalities beyond the Philadelphia chromosome. Which set of changes is classically associated with this transformation?

• A del(5q) and del(7q) only
• B del(13q) and del(11q)
• C t(14;18) and trisomy 12
• D +8, i(17q), and trisomy 21 ✓

Explanation

Blast crisis of CML is marked by acquisition of additional cytogenetic abnormalities in the Ph-positive clone, classically trisomy 8, isochromosome 17q, and trisomy 21, sometimes called the major route changes. Isochromosome 17q implies loss of TP53 function, contributing to transformation. Deletions of 13q and 11q are typical of CLL, and del(5q) with del(7q) suggests therapy-related myeloid neoplasms rather than CML progression.

Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.