Double Minutes and MYC Amplification.

Objectives: To report the demonstration of double minutes with MYC amplification in a case of myeloproliferative neoplasm with monocytosis in transformation by a combination of standard karyotyping and interphase and metaphase fluorescence in situ hybridization (FISH). Methods: To determine the lineage involvement, we applied combined morphology and an interphase FISH study using dual-color break-apart probes for MYC on peripheral blood film. Results: MYC amplification was demonstrated in both myeloid and monocytic cells but not lymphocytes. The MYC amplification was not associated with loss of MYC signals at the homologous 8q24 regions where the genes were located. Furthermore, the extent of MYC amplification has been shown to diminish as the granulocytes mature. Conclusions: Combined morphology and FISH study has shown a pluripotent myeloid disorder and also an inverse relationship between cell maturity and MYC amplification. [ABSTRACT FROM AUTHOR]