[1242] Dual Color Chromogenic In Situ Hybridization (CISH) Is a Rapid, Specific and Sensitive Method for Identifying MYC Translocations in Paraffin-Embedded Tissue
ME Law, A Dogan, ED Remstein. Mayo Clinic, Rochester, MN
Background: The identification of MYC translocations is important for the classification and management of lymphomas. Time is often of the essence as lymphomas that possess MYC translocations proliferate rapidly and often require urgent therapy. Fluorescent in situ hybridization (FISH) using breakapart probes is widely used to determine the presence of this translocation. However, as FISH requires the use of a microscope fitted with epifluorescence, samples must be sent to specially-equipped laboratories, which can be time-consuming and cumbersome. Also, it is difficult to visualize morphology using fluorescence microscopy. A viable alternative is chromogenic in situ hybridization (CISH), which resembles FISH except chromogen/enzyme reaction products that are visible using light microscopy instead of fluorescent tags highlight the appropriate DNA sequences. Our aim was to compare the utility of CISH to FISH in identifying MYC translocations in paraffin-embedded tissue.
Design: Sections from 10 formalin fixed paraffin embedded (FFPE) samples including 6 high-grade B-cell lymphoma samples, 3 cell line cell blocks containing 90%, 10%, and 0% Raji (t(8;14)/IGH-MYC-positive) cells and 1 FFPE normal tonsil were cut at a thickness of 3-5uM and placed onto SuperFrost Plus microscope slides. FISH using a dual color breakapart Myc DNA probe (Dako) was performed and results tabulated. Slides were then de-identified and, using Dako DuoCISH kit, the FISH signals were tagged with anti-FITC-HRP (blue chromogen) and anti-Texas Red-AP (red chromogen). Slides were visually screened to determine the presence or absence of split signals and after the results were recorded the slides were re-identified.
Results:
| Specimen | FISH | CISH |
|---|
| Lymphoma (Cmyc translocation-) | Normal (1/1) | Normal (1/1) | | Lymphoma (Cmyc translocation+) | Abnormal (4/4) | Abnormal (4/4) | | Raji (90% and 10%) | Abnormal (2/2) | Abnormal (2/2) | | Raji (0%) | Normal (1/1) | Normal (1/1) | | Normal tonsil | Normal (1/1) | Normal (1/1) |
Conclusions: In this small cohort, dual color CISH and dual color FISH were both 100% specific and 100% sensitive in determining the presence of MYC translocations using breakapart probes. CISH can also be performed rapidly on FFPE tissue and can be screened and compared to morphology by the pathologist on a standard light microscope. Thus, in addition to its previously demonstrated utility in determining gene region amplification, FFPE CISH is useful in identifying translocations in a rapid, specific and sensitive manner on routine FFPE specimens.
Category: Hematopathology
Wednesday, March 11, 2009 9:30 AM
Poster Session V # 172, Wednesday Morning
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