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Test Code EOSMF Chronic Eosinophilia, Specified FISH, Varies


Ordering Guidance


This test is intended for instances when limited chronic eosinophilia fluorescence in situ hybridization (FISH) probes are needed based on specific abnormalities or abnormalities identified in the diagnostic sample. The FISH probes to be analyzed must be specified on the ordering request. If targeted FISH probes are not included with this test order, test processing will be delayed and the test may be canceled and automatically reordered by the laboratory as EOSFD / Chronic Eosinophilia panel, Diagnostic FISH, Varies.

 

At diagnosis, conventional cytogenetic studies (CHRBM / Chromosome Analysis, Hematologic Disorders, Bone Marrow) and a complete EOSFD / Chronic Eosinophilia panel, Diagnostic FISH, Varies. panel should be performed.

 

If a complete chronic eosinophilia FISH panel is preferred, order EOSFD / Chronic Eosinophilia panel, Diagnostic FISH, Varies.

 

Paraffin embedded tissue testing is not available for chronic eosinophilia.



Shipping Instructions


Advise Express Mail or equivalent if not on courier service.



Necessary Information


1. A list of probes requested for analysis is required. Probes available for this test are listed in the Testing Algorithm section.

2. A reason for testing must be provided. If this information is not provided, an appropriate indication for testing may be entered by Mayo Clinic Laboratories.

3. A flow cytometry and/or a bone marrow pathology report should be submitted with each specimen. The laboratory will not reject testing if this information is not provided, but appropriate testing and interpretation may be compromised or delayed.



Specimen Required


Submit only 1 of the following specimens:

 

Preferred

Specimen Type: Bone marrow

Container/Tube:

Preferred: Yellow top (ACD)

Acceptable: Green top (sodium heparin) or lavender top (EDTA)

Specimen Volume: 2-3 mL

Collection Instructions:

1. It is preferable to send the first aspirate from the bone marrow collection.

2. Invert several times to mix bone marrow.

3. Send bone marrow specimen in original tube. Do not aliquot.

 

Acceptable

Specimen Type: Whole blood

Container/Tube:

Preferred: Yellow top (ACD)

Acceptable: Green top (sodium heparin) or lavender top (EDTA)

Specimen Volume: 6 mL

Collection Instructions:

1. Invert several times to mix blood.

2. Send whole blood specimen in original tube. Do not aliquot.


Secondary ID

614254

Useful For

Detecting recurrent common chromosome abnormalities associated with myeloid/lymphoid neoplasms with eosinophilia and gene rearrangements (including PDGFRA, PDGFRB, FGFR1, JAK2, and ABL1) using client-specified probe set(s)

 

Evaluating specimens in which chromosome studies are unsuccessful

 

An adjunct to conventional chromosome studies in patients with eosinophilia

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
EOSMB Probe, Each Additional (EOSMF) No, (Bill Only) No
EOS3B Probe, Tri-color (EOSMF) No, (Bill Only) No

Testing Algorithm

This test includes a charge for the probe application, analysis, and professional interpretation of results for one probe set (2 individual fluorescence in situ hybridization [FISH] probes or 3 individual FISH probes). Additional charges will be incurred for additional probe sets performed. Analysis charges will be incurred based on the number of cells analyzed per probe set. If no cells are available for analysis, no analysis charges will be incurred.

 

This test is performed using client-specified FISH probes and is not intended as a panel test. Specific probes must be listed in the probe request field. Reflex probes can be performed when appropriate if specified in the order request field.

 

When specified, any of the following probes will be performed:

4q12 deletion or rearrangement, request probe FIP1L1, CHIC2, PDGFRA

t(4q12;var) or PDGFRA rearrangement, request probe PDGFRA break-apart

t(5q32;var) or PDGFRB rearrangement, request probe PDGFRB break-apart

t(8p11.2;var) or FGFR1 rearrangement, request probe FGFR1 break-apart

t(9p24.1;var) or JAK2 rearrangement, request probe JAK2 break-apart

t(9q34;var) or ABL1 rearrangement, request probe ABL1 break-apart

t(9;22)(q34;q11) or BCR::ABL1 fusion, request probe ABL1/BCR

t(13q12.2;var) or FLT3 rearrangement, request probe FLT3 break-apart

 

Appropriate ancillary probes may be performed at consultant discretion to render comprehensive assessment. Any additional probes will have the results included within the final report and will be performed at an additional charge.

 

For more information see Eosinophilia: Bone Marrow Diagnostic Algorithm.

Method Name

Fluorescence In Situ Hybridization (FISH)

Reporting Name

Chronic Eosinophilia, Spec FISH

Specimen Type

Varies

Specimen Minimum Volume

Bone marrow: 1 mL; Whole blood: 2 mL

Specimen Stability Information

Specimen Type Temperature Time
Varies Ambient (preferred)
  Refrigerated 

Reject Due To

All specimens will be evaluated at Mayo Clinic Laboratories for test suitability.

Clinical Information

The myeloid/lymphoid neoplasms with eosinophilia and rearrangements of PDGFRA, PDGFRB, FGFR1, and JAK2 represent a significantly diverse group of hematologic malignancies. Despite the disparate clinical presentations, which include chronic myeloid neoplasms (chronic myelomonocytic leukemia, chronic myeloproliferative neoplasms, chronic eosinophilic leukemia) versus more acute myeloid and lymphoid neoplasms (acute myeloid leukemia, B- and T-lymphoblastic leukemia/lymphoma and mixed phenotypic acute leukemias), this diagnostic subgroup shares rearrangements involving 4 specific gene regions: PDGFRA, PDGFRB, FGFR1, and JAK2.

 

While conventional chromosome studies may detect many of the rearrangements associated with these gene rearrangements, several are cytogenetically "cryptic", including the most common abnormality involving PDGFRA activation. This one megabase submicroscopic, intrachromosomal deletion results in loss of the CHIC2 gene region with subsequent fusion of neighboring genes FIP1L1 and PDGFRA. In addition to this more common, cryptic deletion, the PDGFRA gene has many translocation partners described (at least 15) that similarly result in PDGFRA upregulation.

 

The PDGFRB, FGFR1, and JAK2 gene regions similarly have numerous translocation/inversion partners described, at least 50 for PDGFRB, 10 for FGFR1, and 40 for JAK2. Despite the significant heterogeneity in gene partners, the identification of PDGFRA, PDGFRB, FGFR1, and JAK2 rearrangements is critical for disease categorization and potential therapeutic intervention. Both PDGFRA and PDGFRB have the potential for response to targeted tyrosine kinase inhibitor therapies such as imatinib mesylate. Similarly, JAK2 rearrangements have the potential for response to targeted inhibitor therapy. Rearrangements of FGFR1 are typically more aggressive and less responsive to targeted inhibitors.

 

While not formally included in the World Health Organization categorization of myeloid/lymphoid neoplasms with PDGFRA, PDGFRB, FGFR1, or JAK2 rearrangements, rearrangements of the ABL1 gene, other than with the BCR locus, can result in similar clinical phenotypes. Thus, the ABL1 gene region has been included in this fluorescence in situ hybridization panel evaluation to appropriately interrogate this gene region, particularly since these patients may not be identified by conventional karyotype analysis and may significantly benefit from targeted tyrosine kinase therapies.

Reference Values

An interpretive report will be provided.

Interpretation

A neoplastic clone is detected when the percent of cells with an abnormality exceeds the normal reference range for any given probe set.

 

The absence of an abnormal clone does not rule out the presence of a neoplastic disorder.

Cautions

This test is not approved by the US Food and Drug Administration, and it is best used as an adjunct to clinical and pathologic information.

 

Fluorescence in situ hybridization (FISH) is not a substitute for conventional chromosome studies because the latter detects chromosome abnormalities associated with other hematological disorders that would go undetected in a targeted FISH test. 

 

Bone marrow is the preferred sample type for this FISH test. If bone marrow is not available, a blood specimen may be used if there are neoplastic cells in the blood specimen (as verified by a hematopathologist).

 

If no FISH signals are observed post-hybridization, the case will be released indicating a lack of FISH results.

Clinical Reference

Myeloid/lymphoid neoplasms with eosinophilia and gene rearrangement. In: Swerdlow SH, Campo E, Harris NL, et al, eds. WHO Classification of Tumours. Vol 2. WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues. 4th ed. IARC Press; 2017:71-80

Method Description

This test is performed using commercially available and laboratory-developed probes. Rearrangements or deletions involving CHIC2, PDGFRA, PDGFRB, FGFR1, JAK2, and ABL1 are detected using a tri or dual-color break-apart (BAP) strategy probe sets. Dual-color, dual-fusion fluorescence in situ hybridization (D-FISH) strategy probe sets are used in reflex testing when rearrangements of the PDGFRB and ABL1 gene are detected. For enumeration and BAP strategy probe sets, 100 interphase nuclei are scored; 200 interphase nuclei are scored when D-FISH probes are used. All results are expressed as the percent abnormal nuclei.(Unpublished Mayo method)

Day(s) Performed

Monday through Friday

Report Available

7 to 10 days

Specimen Retention Time

4 weeks

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Test Classification

This test was developed and its performance characteristics determined by Mayo Clinic in a manner consistent with CLIA requirements. It has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information

88271 x2, 88275 x1, 88291 x1-FISH Probe, Analysis, Interpretation; 1 probe sets

88271 x2, 88275 x1-FISH Probe, Analysis; each additional probe set (if appropriate)

88271 x1-FISH Probe; coverage for sets containing 3 probes (if appropriate)

LOINC Code Information

Test ID Test Order Name Order LOINC Value
EOSMF Chronic Eosinophilia, Spec FISH 107544-9

 

Result ID Test Result Name Result LOINC Value
614256 Result Summary 50397-9
614257 Interpretation 69965-2
614258 Result Table 93356-4
614259 Result 62356-1
GC113 Reason for Referral 42349-1
GC114 Probes Requested 78040-3
GC115 Specimen 31208-2
614260 Source 31208-2
614261 Method 85069-3
614262 Additional Information 48767-8
614263 Disclaimer 62364-5
614264 Released By 18771-6

Forms

If not ordering electronically, complete, print, and send a Hematopathology/Cytogenetics Test Request (T726) with the specimen.