ABSTRACT
Prognosis of acute myeloid leukemia relies heavily on the cytogenetic and molecular abnormalities. AML1-ETO fusion protein resulting from t[8;21], a recurring cytogenetic abnormality, is known to be associated with favorable prognosis. Additional molecular defects may, however, co-operate with the fusion proteins and alter the course of the disease. Among the additional cytogenetic defects, presence of Philadelphia [Ph] chromosome has rarely been documented in this subtype. Little is known about the consequences of its interactions with AML1-ETO, and its effect on morphological and clinical picture. Moreover, Ph[+] clones or subclones may appear at any point during the disease course. We herein report one such unusual case of a 26-year-old female, who was diagnosed to have t[8;21] and managed accordingly. During disease relapse after 2.5 years, the bone marrow showed extensive eosinophilia and basophilia. Subsequent molecular testing showed the presence of BCR-ABL in addition to the AML1-ETO fusion product