Isoderivative chromosome 17 with multiple copies of RARα–PML fusions and Tp53 deletion in a rare case of APML

Acute Promyelocytic Leukemia (APML) is a malignancy of cells in myeloid lineage. It is a neoplasm described by proliferation and accumulation of immature neutrophils called promyelocytes in the bone marrow, inhibiting normal cell production, which results in lower numbers of blood cells circulating the body. A minor but significant proportion of patients with APML harbor complex and cryptic rearrangements. Presence of isoderivative 17 with t(15;17) is very rare. We report a case of adult APML with amplification of RARα/PML fusion protein, a consequence of isoderivative 17 with duplication of normal chromosome 15 and 17 and Tp53 deletion on derivative 17. Immunophenotyping by flow cytometry, presence of pancytopenia and epistaxis helped classify the patient as APML. FISH was used for confirmation of the same and indicated involvement of additional abnormalities.