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Test Code PDGF PDGFB (22q13), Dermatofibrosarcoma Protuberans/Giant Cell Fibroblastoma, FISH, Tissue

Reporting Name

PDGFB (22q13), FISH, Ts

Performing Laboratory

Mayo Clinic Laboratories in Rochester

Useful For

Confirming the diagnosis of dermatofibrosarcoma protuberans (DFSP)/giant cell fibroblastoma (GCF) and excluding other spindle neoplasms that closely simulate the DFSP histology, including dermatofibroma (benign fibrous histiocytoma), neurofibroma, spindle cell lipoma, and a variety of other benign and malignant spindle cell neoplasms

Method Name

Fluorescence In Situ Hybridization (FISH)


Necessary Information


1. A pathology report is required in order for testing to be performed. Acceptable pathology reports include working drafts, preliminary pathology or surgical pathology reports.

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.



Specimen Required


Submit only 1 of the following specimens:

 

Specimen Type: Tissue

Preferred: Tissue block

Container/Tube: Formalin-fixed, paraffin-embedded tumor tissue block

Collection Instructions: Blocks prepared with alternative fixation methods may be acceptable; provide fixation method used

 

Acceptable: Slides

Specimen Volume: Four consecutive, unstained, 5 micron-thick sections placed on positively charged slides and 1 hematoxylin and eosin-stained slide


Specimen Type

Tissue

Specimen Minimum Volume

Two consecutive, unstained, 5-micron-thick sections placed on positively charged slides and 1 hematoxylin and eosin-stained slide.

Specimen Stability Information

Specimen Type Temperature Time Special Container
Tissue Ambient (preferred)
  Refrigerated 

Reject Due To

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

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 the PDGFB FISH probe.

 

A positive result is consistent with rearrangement/amplification of the PDGFB gene locus on 22q13 and supports the diagnosis of dermatofibrosarcoma protuberans (DFSP) or giant cell fibroblastoma (GCF). A negative result is consistent with no rearrangement/amplification of the PDGFB gene locus on 22q13. However, this result does not exclude the diagnosis of DFSP or GCF.

 

The degree of PDGFB copy gain/amplification/rearrangement varies in individual tumors and among different cells in the same tumor. It is not currently known if patients with different levels of rearrangement/amplification have the same prognosis and response to therapy.

Day(s) Performed

Monday through Friday

Report Available

7 to 10 days

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

88271x2, 88291-DNA probe, each (first probe set), Interpretation and report

88271x2-DNA probe, each; each additional probe set (if appropriate)

88271x1-DNA probe, each; coverage for sets containing 3 probes (if appropriate)

88271x2-DNA probe, each; coverage for sets containing 4 probes (if appropriate)

88271x3-DNA probe, each; coverage for sets containing 5 probes (if appropriate)

88274 w/modifier 52-Interphase in situ hybridization, <25 cells, each probe set (if appropriate)

88274-Interphase in situ hybridization, 25 to 99 cells, each probe set (if appropriate)        

LOINC Code Information

Test ID Test Order Name Order LOINC Value
PDGF PDGFB (22q13), FISH, Ts In Process

 

Result ID Test Result Name Result LOINC Value
54697 Result Summary 50397-9
54700 Interpretation 69965-2
54699 Result 62356-1
CG928 Reason For Referral 42349-1
54919 Specimen 31208-2
54702 Source 31208-2
54703 Tissue ID 80398-1
55130 Method 85069-3
55131 Additional Information 48767-8
53397 Disclaimer 62364-5
54704 Released By 19139-5

Forms

If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.

Reflex Tests

Test ID Reporting Name Available Separately Always Performed
_PBCT Probe, +2 No, (Bill Only) No
_PADD Probe, +1 No, (Bill Only) No
_PB02 Probe, +2 No, (Bill Only) No
_PB03 Probe, +3 No, (Bill Only) No
_IL25 Interphases, <25 No, (Bill Only) No
_I099 Interphases, 25-99 No, (Bill Only) No
_I300 Interphases, >=100 No, (Bill Only) No

Testing Algorithm

This test does not include a pathology consultation. If a pathology consultation is requested, PATHC / Pathology Consultation should be ordered, and the appropriate fluorescence in situ hybridization (FISH) test will be performed at an additional charge.

 

This test includes a charge for application of the first probe set (2 FISH probes) and professional interpretation of results.

 

Additional charges will be incurred for all reflex probes 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.

 

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.