Bone Marrow Conventional Karyotyping and Fluorescence In Situ Hybridization:  Defining an Effective Utilization Strategy for Evaluation of Myelodysplastic Syndromes.

OBJECTIVES: The current standard of practice for evaluation of myelodysplastic syndromes (MDS) includes peripheral blood and bone marrow morphology review and conventional karyotyping. Karyotype provides a global view of the chromosome complement while fluorescence in situ hybridization (FISH) targets specific abnormalities. The aim of this study was to determine if an MDS-FISH panel would add value beyond karyotype in MDS workup.

METHODS: We studied 505 patients who were evaluated for a possible MDS and had concurrent bone marrow examination, karyotyping, and MDS-FISH performed.

RESULTS: In total, 462 cases had adequate karyotyping (≥20 metaphases) and showed excellent concordance (96%, 445/462) between karyotyping and MDS-FISH. Additional FISH abnormalities had no impact on diagnosis and minimal impact on the cytogenetic prognostic scoring in the myeloid neoplasm cases (2%, 4/206). The concordance rate dropped to 82% (32/39) in the group with insufficient karyotyping (<20 metaphases), and additional FISH findings in this subgroup had no impact on the diagnosis but altered the cytogenetic prognostic scoring in 10% (2/20) of myeloid neoplasm cases.

CONCLUSIONS: In the evaluation of a possible MDS, FISH rarely provides additional value when karyotype is adequate. We propose a value-based, cost-effective algorithmic approach for conventional karyotyping and FISH testing in routine MDS workup.