Germ Cell Tumor (GCT), Isochromosome 12p, FISH, Tissue
NY State Approved Indicates the status of NY State approval and if the test is orderable for NY State clients.
Supporting the diagnosis of germ cell tumors when used in conjunction with an anatomic pathology consultation
Testing Algorithm Delineates situation(s) when tests are added to the initial order. This includes reflex and additional tests.
This test does not include a pathology consult. If a pathology consultation is requested, 70012 Pathology Consultation should be ordered and the appropriate FISH test will be ordered and performed at an additional charge.
Fluorescence In Situ Hybridization (FISH)
Reporting Name A shorter/abbreviated version of the Published Name for a test; an abbreviated test name
Germ Cell Tumor, FISH, Ts
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.
Please provide a pathology report with each specimen. The laboratory will not reject a specimen that arrives without this information but will hold the specimen until a pathology report is received.
Submit only 1 of the following specimens:
Preferred: Formalin-fixed, paraffin-embedded tumor tissue block and 1 hematoxylin and eosin (H and E)-stained slide
Acceptable: Four consecutive, unstained, 5 micron-thick sections placed on positively-charged slides and 1 H and E-stained slide
Forms: If not ordering electronically, complete and submit a Hematopathology/Molecular Oncology Request Form (Supply T241) with the specimen.
Specimen Minimum Volume Defines the amount of specimen required to perform an assay once, including instrument and container dead space. Submitting the minimum specimen volume makes it impossible to repeat the test or perform confirmatory or perform reflex testing. In some situations, a minimum specimen volume may result in a QNS (quantity not sufficient) result, requiring a second specimen to be collected.
2 unstained slides and 1 hematoxylin-and-eosin (H and E) slide
Note: No specimen should be rejected. If specimen not received at appropriate temperature or in wrong anticoagulant, include note to laboratory. If questions, contact laboratory.
Specimen Stability Information Provides a description of the temperatures required to transport a specimen to the laboratory. Alternate acceptable temperature(s) are also included.
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
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 provide 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 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.
An interpretive report will be provided.
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 the diagnosis of a germ cell tumors (GCT).
A negative result suggests that the i(12p) marker is not present, but does not exclude the diagnosis of a GCT.
Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances
This test is not approved by the FDA and it is best used as an adjunct to existing clinical and pathologic information.
Fixatives other than formalin (eg, Prefer, Bouin's) may not be successful for FISH assays. Although FISH testing will not be rejected due to nonformalin fixation, results may be compromised.
Paraffin embedded tissues that have been decalcified are generally unsuccessful for FISH analysis. The pathologist reviewing the hematoxylin and eosin-stained slide may find it necessary to cancel testing.
FISH analysis was performed on 171 formalin-fixed, paraffin-embedded tissue samples from the testis, ovary, and brain. These included 22 dysgerminomas, 20 seminomas, 10 mixed germ cell tumors (GCT), 18 germinoma, 4 embryonal carcinoma, 22 GCT histological mimics, and 75 noncancerous control specimens. The normal controls were used to generate a normal cutoff for this assay. The presence of i(12p) was identified in 29% of brain, 55% of testis, and 56% of ovarian GCT.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Woodward PJ, Heidenreich A, Looijenga LHJ, et al: Germ cell tumors. WHO classification of tumors: Pathology and Genetics of Tumors of the Urinary System and Male Genital Organs. 2004
2. Wehle D, Yonescu R, Long PP, et al: 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;June;183(2):99-104
3. Poulos C, Cheng L, Zhang S, et al: Analysis of ovarian teratomas for Isochromosome 12p: evidence supporting a dual histogenetic pathway for teratomatous elements. Mod Pathology 2006;19:766-771
Method Description Describes how the test is performed and provides a method-specific reference
This test uses a commercially available chromosome 12 centromere probe (D12Z3) and a laboratory-developed probe targeted to 12p11.21. Formalin-fixed, paraffin-embedded tissues are cut at 5 microns and mounted on positively-charged glass slides. The selection of tissue and the identification of target areas on the hematoxylin and eosin (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. The probe set is hybridized to the appropriate target areas and 2 technologists each analyze 50 interphase nuclei each (100 total) with the results expressed as percent abnormal nuclei.(Unpublished Mayo method)
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.
Samples processed Monday through Sunday. Results reported Monday through Friday 8am-5pm CST
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.
This test was developed using an analyte specific reagent. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the U.S. Food and Drug Administration.
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.
Germ Cell Tumor (GCT), Isochromosome 12p, FISH, Tissue
88271 x 2-DNA probe, each
88275-Interphase in situ hybridization, 100-300 cells
88291-Interpretation and report
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|
|CG291||Reason For Referral||42349-1|