FISH-MM

Fluorescence In Situ Hybridization – Multiple Myeloma Panel

Test Overview

CPT Code(s)

88237-52, 88271×3, 88275, 88291

Methodology

Plasma cell isolation/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

Plasma cell disorders are genetically diverse group of diseases arising from malignant proliferation of monoclonal population of plasma cells.  This group consists of monoclonal gammopathy of undetermined significance (MGUS), plasma cytoma, smoldering myeloma, and plasma cell myeloma or multiple myeloma.  Genomic abnormalities are important prognostic factors in myeloma.  Routine chromosome anlaysis is often limiting and is not efficient in detecting these genomic abnormalities since there is limited infiltration of plasma cells in the bone marrow and also due to the slow proliferation of plasma cells.  Studies have shown enrichment for plasma cells is most efficient in detecting these prognostically significant genomic abnormalities.  Our lab has unique expertise in isolating plasma cells and using the negative fraction for routine chromosome analysis to detect non-plasma cell abnormalities.  In fact, we are the first laboratory to design a protocol utilizing the negative fraction for chromosome analysis with considerable success.

Methods

The plasma cells are isolated using a CD134 magnetic antibody separation method. The isolated plasma cells are harvested and hybridized 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 multiple myeloma panel includes the following probes.

11q deletionD11Z1 / ATMCytocell (cat # LPH011)
17p deletionp53Cytocell (cat # LPH017)
13q deletionRB1 / CTB-163C9Cytocell (cat # LPS011)
t(11;14)CCND1 / IGHCytocell (cat # LPH021)
t(4;14)FGFR3 / IGHCytocell (cat # LPH030)
t(14;16)IGH / MAFCytocell (cat # LPH029)
hyperdiploidyATM / MAF / FGFR3

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.