Therapy-related MDS: the importance of repeating cytogenetics and immunophenotyping in “relapsed” AML

Abstract

Therapy-related myelodysplastic syndromes (t-MDS) occurring after the successful treatment of acute myeloid leukaemia (AML) are rare and may be difficult to distinguish from relapse of the primary leukaemia, especially if the second neoplasm overlaps morphologically with the initial one. We report a 78-year-old male who, 3 years after treatment for acute monocytic leukaemia, developed t-MDS (refractory anaemia with excess blasts-2) that was initially suspected to be a relapse. Cytogenetic analysis of the initial AML had revealed +8 and del(16). These abnormalities disappeared, along with monocytic markers on flow cytometry, 3 years later, and a new t(3;7) event was found instead. The cytogenetic findings, together with the clinical profile, the morphological data and the immunophenotypic shift, were crucial in correctly recognizing the t-MDS and excluding relapse. Repeat genetic and immunological analyses are often omitted at the time of morphologically evident relapse in AML, especially for economic reasons in resource-constrained settings. Our case shows that such investigations may be invaluable in avoiding a misdiagnosis and, indeed, may help reveal the true incidence of t-MDS/t-AML in treated AML patients.