Diagnostic and Prognostic Significance Of Isolated Trisomy 2 In Hematopoietic Malignancies

Isolated trisomy 2 in hematopoietic malignancies is rare, having only been reported in eight cases in the literature. Of these cases, the majority are older male patients (7/8) ranging in age from 64 to 84 years. The underlying hematologic malignancies include: myelodysplastic syndrome (MDS), refractory anemia (RA) subtype; MDS, RA with excess blasts (RAEB-II) subtype; MDS, RAEB in transformation (RAEB-t); chronic myelomonocytic leukemia (CMML-t) in transformation; MDS transformed into AML; acute monoblastic and monocytic leukemia (AMoL; FAB M5); and AML in relapse. The molecular pathogenesis and prognostic significance of isolated trisomy 2 remains unknown due to the small number of reported cases. Herein, we report 11 cases of isolated trisomy 2 in hematologic disorders seen in the Mayo Clinic Cytogenetics laboratory from 1996-2012. The majority of patients were older males (7/11) ranging in age from 63 to 93 years. The underlying bone marrow pathologic diagnoses include: hypercellular bone marrow without diagnostic features of malignancy (cases 1 and 2); MDS, refractory cytopenia with multilineage dysplasia (RCMD) subtype (cases 3 and 4); RAEB-1 (cases 5 and 6); long-standing history of primary myelofibrosis now with 7% bone marrow blasts (case 7); acute myeloid leukemia (AML), not otherwise specified (cases 8 and 9); AML with myelodysplasia-related changes (cases 10 and 11). Trisomy 2 has been suggested to represent an age-related phenomenon as it is seen predominantly in older individuals demonstrating this abnormality. Our data suggests that this could be a possible explanation since all of the eleven cases were ages 63 and over. Based on the limited clinical information in our study, it appears that isolated trisomy 2 harbors little prognostic significance and that, rather, the prognostic significance is driven by the underlying pathologic diagnosis. For example, 3 of the 4 AML cases and the case of PMF with increasing bone marrow blasts survived only 7, 8, 6 weeks and 21 weeks post bone marrow biopsy/cytogenetic evaluation, respectively. Although our study only has two cases that lack diagnostic features of malignancy, one of these cases survived 10 years following the identification of the cytogenetic abnormality. Therefore, trisomy 2 as a sole abnormality should not be considered as definitive evidence for MDS in the absence of diagnostic morphological criteria (similar to trisomy 8 and 20q deletion).