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HelpTest ID: GCTF Germ Cell Tumor (GCT), Isochromosome 12p, FISH, Tissue
Useful For
Supporting the diagnosis of germ cell tumors when used conjunction with an anatomic pathology consultation
Reflex Tests
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| _I099 | Interphases, 25-99 | No, (Bill Only) | No |
| _I300 | Interphases, >=100 | No, (Bill Only) | No |
| _IL25 | Interphases, <25 | 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 |
| _PBCT | Probe, +2 | 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 probes). No analysis charges will be incurred if an insufficient number of representative cells are available for analysis.
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.
Method Name
Fluorescence In Situ Hybridization (FISH)
Reporting Name
i(12p), Germ Cell Tumor, FISH, TsSpecimen Type
TissueOrdering Guidance
This test does not include a pathology consultation. If a pathology consultation is requested, order PATHC / Pathology Consultation, and appropriate testing will be added at the discretion of the pathologist and performed at an additional charge.
Multiple oncology (cancer) gene panels are also available. For more information see Hematology, Oncology, and Hereditary Test Selection Guide.
Shipping Instructions
Advise Express Mail or equivalent if not on courier service.
Necessary Information
1. A pathology report is required for testing to be performed. If not provided, appropriate testing and/or interpretation may be compromised or delayed. Acceptable pathology reports include working drafts, preliminary pathology, or surgical pathology reports.
2. The following information must be included in the report provided.
1. Patient name
2. Block number - must be on all blocks, slides, and paperwork
3. Date of collection
4. Tissue Source
3. 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:
Preferred
Specimen Type: Tissue block
Collection Instructions: Submit a formalin-fixed, paraffin-embedded (FFPE) tumor tissue block. Blocks prepared with alternative fixation methods will be attempted but are less favorable for successful results by FISH testing; provide fixation method used.
Additional Information:
1. Paraffin-embedded specimens can be from any anatomic location (skin, soft tissue, lymph node, etc).
2. Bone specimens that have been decalcified will be attempted for testing, but the success rate is approximately 50%.
Acceptable
Specimen Type: Tissue slides
Slides: 1 Hematoxylin and eosin stained and 4 unstained
Collection Instructions: Submit 4 consecutive unstained, positively charged, unbaked slides with 5 micron-thick sections of the tumor tissue and 1 slide stained with hematoxylin and eosin.
Specimen Minimum Volume
Slides: 1 Hematoxylin and eosin stained and 2 unstained
Specimen Stability Information
| Specimen Type | Temperature | Time | Special Container |
|---|---|---|---|
| Tissue | Ambient (preferred) | ||
| Refrigerated | |||
Clinical Information
Germ cell tumors (GCT) comprise a heterogeneous group of solid neoplasms that arise in midline locations including the gonads, retroperitoneum, mediastinum, and central nervous system. GCT are categorized based upon their histologic differentiation and can be separated into 2 classes. Seminomatous GCT include seminoma of the testis, dysgerminoma of the ovaries, and germinoma of the brain. Nonseminomatous GCT include yolk sac tumor, embryonal carcinoma, choriocarcinoma, immature teratoma, and mixed forms. Due to the wide spectrum of histologic features observed in these tumors, distinction from non-GCT can be difficult. GCT are often very responsive to chemotherapy and have a better outcome relative to histologically similar malignancies. Thus, distinguishing GCT from non-GCT is critical to providing the appropriate treatment for the patient. Gain of the short arm of chromosome 12, most commonly as an isochromosome 12p [i(12p)], is a highly nonrandom chromosomal marker seen in a significant percentage of GCT. While i(12p) is not 100% specific for GCT, the literature indicates it has diagnostic and possible therapeutic relevance for patients with these tumors. Testing of i(12p) should be concomitant with histologic evaluation, and positive results may support the diagnosis of GCT.
Reference Values
An interpretive report will be provided.
Interpretation
Testing will be clinically interpreted as positive or negative.
A neoplastic clone is detected when the percent of cells with an abnormality exceeds the normal cutoff for the i(12p) probe set.
A positive result is consistent with an isochromosome 12p. The significance of this finding is dependent on the clinical and pathologic features.
A negative result suggests an isochromosome 12p is not present but does not exclude the diagnosis of germ cell tumors.
Clinical Reference
1. Wehle D, Yonescu R, Long PP, Gala N, Epstein J, Griffin CA. Fluorescence in situ hybridization of 12p in germ cell tumors using a bacterial artificial chromosome clone 12p probe on paraffin-embedded tissue: clinical test validation. Cancer Genet Cytogenet. 2008;183(2):99-104
2. Poulos C, Cheng L, Zhang S, Gersell DJ, Ulbright TM. Analysis of ovarian teratomas for isochromosome 12p: evidence supporting a dual histogenetic pathway for teratomatous elements. Mod Pathol. 2006;19(6):766-771
3. Chaganti RS, Houldsworth J. Genetics and biology of adult human male germ cell tumors. Cancer Res. 2000;60(6):1475-1482
4. Freitag CE, Sukov WR, Bryce AH, et al. Assessment of isochromosome 12p and 12p abnormalities in germ cell tumors using fluorescence in situ hybridization, single-nucleotide polymorphism arrays, and next-generation sequencing/mate-pair sequencing. Hum Pathol. 2021;112:20-34
Day(s) Performed
Monday through Friday
Report Available
7 to 10 daysTest 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)Â Â Â Â Â Â Â Â
LOINC Code Information
| Test ID | Test Order Name | Order LOINC Value |
|---|---|---|
| GCTF | i(12p), Germ Cell Tumor, FISH, Ts | In Process |
| Result ID | Test Result Name | Result LOINC Value |
|---|---|---|
| 52051 | Result Summary | 50397-9 |
| 52053 | Interpretation | 69965-2 |
| 52052 | Result | 62356-1 |
| CG726 | Reason For Referral | 42349-1 |
| CG725 | Specimen | 31208-2 |
| 52054 | Source | 31208-2 |
| 52055 | Tissue ID | 80398-1 |
| 52056 | Method | 85069-3 |
| 54571 | Additional Information | 48767-8 |
| 53844 | Disclaimer | 62364-5 |
| 52057 | Released By | 18771-6 |
Forms
If not ordering electronically, complete, print, and send an Oncology Test Request (T729) with the specimen.
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