Abstract

The incidence of therapy-related Acute Promyelocytic Leukemia (t-APL) has been steadily rising. Radioactive Iodine (RAI) has emerged as a potential leukemogenic insult. Translocation involving the Retinoic Acid Receptor-alpha (RAR-alpha, RARa) gene on chromosome 17 and the Promyelocytic Leukemia (PML) gene on chromosome 15, denoted t(15;17), is pathognomonic of Acute Promyelocytic Leukemia (APL) leading to production of the classic PML/RARA fusion gene. This translocation interferes with the normal function of PML and RARa genes leading to abnormal proliferation of immature leukocytes that are in the promyelocytic stage. Trisomy of chromosome 8 is the most common additional genetic abnormality in t-APL with t(15;17), but cases of deletion in the long arm of chromosome 9 (9q deletion) have also been reported in de novo APL. Recent studies have suggested that 9q deletion in de novo APL is associated with poor overall survival. To our knowledge, 9q deletion in addition to the pathognomonic t(15;17) has not been described in t-APL. We report a case of interstitial deletion of 9q in a patient diagnosed with acute promyelocytic leukemia with prior exposure to RAI.

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