FISH-MPD

Fluorescence In Situ Hybridization – MPD Panel

Test Overview

CPT Code(s)

88237-52, 88271×3, 88275, 88291

Methodology

Culture/Hybridization/Microscopy/Interpretation

Specimen Requirements

Bone Marrow and/or Leukemia Blood

Container: Sodium Heparin (green top tube)

Optimal Quantity: 2-3 ml

Minimum Quantity: 1-2 ml

Storage: Room Temperature

Stability at Room Temperature: 8 hours, then refrigerate

Transportation: Avoid freezing or heating over 35oC

Test Details

Clinical Significance

Fluorescence in situ hybridization (FISH) is a sensitive method to detect smaller genomic changes associated with various hematological malignancies and solid tumors.  There are several advantages with FISH technology over routine chromosome analysis and such advantages include the ability of FISH technology to detect genomic abnormalities in non-viable and non-dividing tissues, rapid turnaround time, and increased resolution.  However, FISH technology is complementary to routine chromosome analysis and cannot substitute routine chromosome analysis for diagnosis of cancer.

Clinical Background

Myeloproliferative neoplasms associated with activated tyrosine kinase and presenting with eosinophilia are a distinct group of myeloproliferative and lymphoid neoplasms.  These neoplasms, especially those with rearrangements involving the platelet derived growth factor receptor alpha (PDGFRA), platelet derived growth factor receptor beta (PDGFRB), fibroblast growth factor receptor 1 (FGFR1) and BCR/ABL1 fusion, respond well to treatment with tyrosine kinase inhibitors like imatinib and hence are called imatinib responsive neoplasms.  The most common chromosomal rearrangements seen in this group include t(4;12) resulting in PDGFRA rearrangement, t(5;12) resulting in PDGFRB rearrangement, t(9;22) resulting in BCR/ABL1 rearrangement  and chromosome 8 abnormalities resulting in FGFR1rearrangements.  Although some of these chromosome abnormalities can be detected on routine chromosome analysis, FISH is more sensitive in identifying and accurately characterizing the underlying gene rearrangements and hence is the preferred method for diagnosis.

Methods

The samples are usually cultured for 24-hours before hybridizing with the probes.  After hybridization and post-hybridization washes, the slides are analyzed under a fluorescence microscope equipped with epifluorescence and appropriate filter sets.  Analysis and scoring is carried out by two certified technologists in a blinded fashion.  Results are reviewed by both the laboratory manager and the director. The MPD panel includes the following probes.

t(9;22)ABL1 / BCRCytocell (cat # LPH038)
4q rearrangementFIP1L1 / CHIC2 / PDGFRACytocell (cat # LPH032)
t(5;12)PDGFRBCytocell (cat # LPH031)
8p11 rearrangementFGFR1Cytocell (cat # LPS018)

Interpretation of Results

The morphologic interpretation and correlation of results on all cases is performed by a board-certified doctoral level scientist (laboratory director). The final report has a narrative description of results.  If abnormalities are present, they are explained in a paragraph which helps to clarify and correlate chromosomal findings with phenotype. References are included in the report to help the referring physician with interpretation, which include books or journals that contain appropriate information. Recommendations are made as to any additional testing, if necessary.