Detection of numerical chromosome 17 abnormalities in fine-needle aspirates of breast cancer using a novel in situ hybridization signal amplification method

We describe a method of in situ hybridization (ISH) to assess numerical chromosome abnormalities on alcohol-fixed smears obtained by fine-needle aspiration from breast cancer patients, using a commercially available amplification kit to demonstrate numerical chromosome alterations of chromosome 17. In this staining procedure after detection of the biotin-labeled α-satellite probe for chromosome 17 with avidin-biotin-peroxidase, we incorporated a signal amplification based on the peroxidase-catalyzed deposition of a biotinylated phenolic compound followed by a secondary reaction with peroxidase. The reactions are revealed by deposition of diaminobenzidine and can be analyzed in an optical microscope, with total preservation of the morphology, allowing a direct morphologic-cytogenetic correlation. A series of 25 cases of aspirates from breast cancer were analyzed with this methodology. Aneusomy was found in 14 cases (56%), whereas 11 (44%) had a normal number of chromosome 17 copies. Polysomy occurred in all aneusome cases except one. We did not find concordance between numerical chromosome abnormalities of chromosome 17 and nuclear grading as well as with the immunoexpression of p53 and c-erbB2 studied in the smears. We conclude that the application of the ISH signal amplification method on alcohol-fixed smears will eliminate the need for fresh material and will provide several advantages, such as improvement of morphological concomitant analysis without the need for a fluorescence microscope; utilization, whenever malignancy is found, without necessity to reaspirate the patient; and adequacy of archival material. Diagn. Cytopathol. 1998;19:141–146. © 1998 Wiley-Liss, Inc.