DETECTION OF THE PHILADELPHIA-CHROMOSOME IN PARAFFIN-EMBEDDED TISSUE BY FLUORESCENCE IN-SITU HYBRIDIZATION

The bcr-abl fusion gene situated on the Philadelphia chromosome is a t umor-specific marker for chronic myelogenous leukemia. We evaluated th e usefulness of two color fluorescence in situ hybridization with bcr and abl probes as a means of detecting the Philadelphia chromosome in formalin-fixed, paraffin-embedded sections of spleen and lymph node sp ecimens from eight patients with myeloproliferative diseases showing c linical and morphological features of chronic myelogenous leukemia in accelerated phase. Our analysis showed co-localized hybridization sign als corresponding to the bcr-abl fusion product in tissue sections fro m six patients previously found to have the Philadelphia chromosome by conventional cytogenetics and polymerase chain reaction. The two rema ining specimens lacked bcr-abl fusion signals and were obtained from p atients who were negative for the Philadelphia chromosome by cytogenet ic and polymerase chain reaction analysis. We conclude that fluorescen ce in situ hybridization is a sensitive method for the detection of th e bcr-abl fusion gene in histological specimens from patients with chr onic myelogenous leukemia. The technique may become a useful tool in t he evaluation of tissue specimens from patients with chronic myelogeno us leukemia and related Philadelphia chromosome-positive hematologic m alignancies.