Interphase cytogenetics of hematological neoplasms under the perspective of the novel WHO classification.

The novel WHO classification of tumors of hematopoietic and lymphoid tissues highlights the importance of genetic aberrations for the proper diagnosis of these malignancies. Among those techniques allowing detection of chromosomal changes, we have shown repeatedly that interphase fluorescence in situ hybridization (FISH) is currently the most robust and reliable technique for the diagnosis of lymphoma-associated translocations. Interphase FISH assays for the detection of the most frequent chromosomal alterations in myeloid and lymphoid disorders have become commercially available during the recent past. The sensitivity of some of these assays reaches levels below 1% providing valuable tools not only for diagnosis but also for follow-up and detection of minimal residual disease. Improvements of interphase FISH include the development of multicolor interphase FISH assays to detect several of the diagnostic changes in a single cell and of simultaneous fluorescence immunophenotyping (FICTION technique) to correlate phenotypic and genotypic cell features.