Test ID: 88905
PDGFB, 22q13, for Dermatofibrosarcoma Protuberans/Giant Cell Fibroblastoma, FISH
Secondary ID 
A test code used for billing and in test definitions created prior to November 2011
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Useful For Suggests clinical disorders or settings where the test may be helpful
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
Additional Tests Lists test(s) that are always performed, at an additional charge, with the initial test(s)
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| 60254 | AP Special Studies Review | No | Yes |
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
This test is performed in conjunction with 60254 AP Special Studies Review. Additional testing may be performed after review by pathologist. Upon approval from the requesting clinician, 60254 AP Special Studies Review could be changed to 5439 Surgical Pathology Consultation, if determined to be more appropriate.
Special Instructions and Forms Describes specimen collection and preparation information, test algorithms, and other information pertinent to test. Also includes pertinent information and consent forms to be used when requesting a particular test
Method Name A short description of the method used to perform the test
Fluorescence In Situ Hybridization (FISH) with DNA Probes
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Aliases Lists additional common names for a test, as an aid in searching
DFSP/GCF
GCF
PDGFB
COL1A1
COL1A1-PDGFB
COL1A1/PDGFB
t(17;22)
17;22 translocation
Translocation 17;22
Specimen Type Describes the specimen type needed for testing
Specimen Required Defines the optimal specimen. This field describes the type of specimen required to perform the test and the preferred volume to complete testing. The volume allows automated processing, fastest throughput and, when indicated, repeat or reflex testing.
A pathology/diagnostic report and a brief history are required.
Specimen Type:
Preferred: Formalin-fixed, paraffin-embedded (FFPE) tissue
Acceptable: Unstained glass, "positively charged" slides with FFPE tissue; slides may be stained and/or scraped
Collection Instructions:
1. Process all specimens into FFPE blocks prior to submission.
2. If submitting slides, a minimum of ten, 4- to 5-micron thick, unstained slides are required if also requesting a surgical pathology consultation; a minimum of three, 4- to 5-micron thick, unstained slides are required if not requesting a surgical pathology consultation.
Additional Information:
1. A quality specimen is essential for evaluation. Submit only tissue containing tumor cells; minimal tissue is required for evaluation.
2. Special stains performed outside Mayo Medical Laboratories and included with the case may be repeated and charged at the reviewing pathologist's discretion. Testing requested by referring physician may not be performed if deemed unnecessary by Mayo Clinic pathologist.
Forms: If not ordering electronically, submit a Pathology/Cytology Request Form (Supply T246) with the specimen.
Reject Due To Identifies specimen types and conditions that may cause the specimen to be rejected
| Hemolysis | NA |
| Lipemia | NA |
| Icterus | NA |
| Other | Decalcified specimens |
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
| Specimen Type | Temperature | Time |
|---|---|---|
| Varies | Ambient (preferred) | |
| Refrigerated | ||
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Dermatofibrosarcoma protuberans (DFSP) is a superficial, low-grade sarcoma genetically characterized by the unbalanced chromosomal translocation t(17;22)(q21;q13), usually in the form of a supernumerary ring chromosome. The product of this chromosomal translocation is the chimeric gene COL1A1-PDGFB. Rearrangements of this gene have been detected in approximately 90% of DFSP and its related infantile form, giant cell fibroblastoma, but not in other tumors.
Reference Values Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.
0-9% rearranged cells
Interpretation Provides information to assist in interpretation of the test results
An interpretative report will be provided.
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.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
Reliable results are dependent on adequate specimen collection and processing. This test has been validated on formalin-fixed, paraffin-embedded tissues; other types of fixatives are discouraged. Improper treatment of tissues, such as decalcification, may cause FISH failure.
Clinical diagnosis and/or therapy should not be based solely on this assay. The results should be considered in conjunction with clinical information, histologic analysis, and/or additional diagnostic tests.
Supportive Data
A blinded investigation was performed on 49 formalin-fixed, paraffin-embedded tissues including 24 dermatofibrosarcoma protuberans (DFSP) tumors, 5 giant cell fibroblastoma (GCF) tumors, and 20 non-DFSP/GCF tumors. Each specimen had been previously characterized by 2 experienced, soft tissue pathologists. Two technologists scored 100 interphase nuclei for each specimen (200 total cells/case). Results showed that 20 of the 24 DFSP tumors had amplification of PDGFB, 1 had a rearrangement, and 3 were negative for both amplification and rearrangement. Each of the 20 non-DFSP/GCF tumors yielded normal results (ie, negative for both rearrangement and amplification). The 5 of the 5 GCF cases were also identified as abnormal.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Abbott JJ, Erickson-Johnson M, Wang X, et al: Gains of COL1A1-PDGFB genomic copies occur in fibrosarcomatous transformation of dermatofibrosarcoma protuberans. Mod Pathol 2006 Nov;19(11):1512-1518
2. Labropoulos SV, Fletcher JA, Oliveira AM, et al: Sustained complete remission of metastatic dermatofibrosarcoma protuberans with imatinib mesylate. Anticancer Drugs 2005 April;16(4):461-466
3. Macarenco RS, Zamolyi R, Franco MF, et al: Genomic gains of COL1A1-PDGFB occur in the evolution of giant cell fibroblastoma into dermatofibrosarcoma protuberans. Genes Chromosomes Cancer 2008 Mar;47(3):260-265
Method Description Describes how the test is performed and provides a method-specific reference
Formalin-fixed, paraffin-embedded tissues are cut at 4 microns and mounted on positively-charged glass slides. Five slides are prepared, with 2 slides stained with hematoxylin and eosin (H and E); the other 3 are left as unstained slides. The selection of tissue and the identification of target areas on an H and E-stained slide is performed by a pathologist. Using the H and E slide as a reference, target areas are etched with a diamond-tipped etcher on the back of the unstained slide to be assayed. Abnormalities involving the PDGFB locus at 22q13 are detected using a break-apart PDGFB FISH probe (Mayo-developed). The break-apart probe design consists of a 3' flanking region of the PDGFB gene labeled in SpectrumGreen (G) and a 5' flanking region labeled in SpectrumOrange (R). The probe set is applied to the appropriate target areas, denatured, and hybridized overnight. Two independent scorers analyze 100 interphase nuclei each (200 total). Normal interphase nuclei show 2 yellow fusion (F) signals caused by juxtaposition of the R and G signals, which indicates genomic integrity of the PDGFB locus on 22q13. Normal patterns also include 1F (up to 30%), 1F+1R (up to 10%), and 1F+1G (up to 10%). Abnormal nuclei will have split of the R and G indicating rearrangement (signal pattern of 1R1G1F), or will have 2F plus multiple red signals, consistent with the presence of the formation of a supernumerary ring chromosome. If the results of the 2 observers are acceptable, the result will be reported out as positive or negative for rearrangement/amplification of the PDGFB locus 22q13 according to the 2005 ISCN nomenclature. The results are interpreted and reported by a working group pathologist.(Abbott JJ, Erickson-Johnson M, Wang X, et al: Gains of COL1A1-PDGFB genomic copies occur in fibrosarcomatous transformation of dermatofibrosarcoma protuberans. Mod Pathol 2006 November;19[11]:1512-1518)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; 8 a.m.-4:30 p.m.
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test
Test Classification Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer's instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR), Investigation Use Only (IUO) product, or a Research Use Only (RUO) product.
CPT Code Information Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Medical Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.
PDGFB, 22q13, for Dermatofibrosarcoma Protuberans/Giant Cell Fibroblastoma, FISH
88368-Morphometric analysis, in situ hybridization (quantitative or semi-quantitative) each probe; manual
LOINC® Code Information Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the result codes returned for this test or profile.
| Result ID | Reporting Name | LOINC Code |
|---|---|---|
| 88905 | PDGFB, 22q13, FISH | In Process |
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