Demonstration of the Philadelphia translocation by fluorescence in situ hybridization (FISH) in paraffin sections and identification of aberrant cells by a combined FISH/immunophenotyping approach.

The Philadelphia translocation was demonstrated by two-colour fluorescence in situ hybridization (FISH) in decalcified paraffin sections of bone marrow from patients with chronic myelogenous leukaemia. FISH was combined with immunocytochemical detection of different membrane-bound or cytoplasmic antigens. With this new technique, the cells bearing the 9:22 translocation can be identified morphologically, as well as immunocytochemically, in tissue sections.