Trisomy 9 in a patient with secondary acute myelogenous leukemia detected by fluorescent in situ hybridization

Fluorescent in situ hybridization (FISH) is a molecular cytogenetic techniq ue that is playing an increasingly important role for augmenting the findin gs of conventional cytogenetics. Here we present the case history of a pati ent with the clinical diagnosis of secondary acute myelogenous leukemia who se bone marrow cells were found to be hyperdiploid with an extra C group ch romosome in a less than optimal preparation, By using FISH the extra chromo some was unequivocally determined to be a chromosome 9. The detection of tr isomy 9 in this patient underscores the utility of FISH as an adjunct to GT G banding in the routine diagnosis and management of leukemic patients.