Identification of the true hyperdiploid multiple myeloma subset by combining conventional karyotyping and FISH analysis

Multiple myeloma (MM) is a malignant disorder of plasma cells representing the second most common hematological malignancy 1 . The currently accepted MM pathogenetic model includes two different types of primary events, namely chromosome translocations or chromosome number alterations resulting in hyperdiploidy 2 . Primary translocations, often associated with hypodiploid karyotype, can be found in at least 40% of patients 3 . Among these translocations, t(4;14) and t(14;16), found in 10–15% and 2–3% of patients, respectively, are associated with a worse outcome, and included in the revised ISS 3 , 4 . More than half of MM cases, instead, have a hyperdiploid karyotype, characterized by trisomies involving odd chromosomes. In several studies, trisomic MM is associated with a favorable outcome 3 , 5 .