Test Id : MESOF

This test includes a charge for application of the first probe set (2 fluorescence in situ hybridization probes) and professional interpretation of results. Additional charges will be incurred for application of 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.

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

Advise Express Mail or equivalent if not on courier service.

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.

Submit only 1 of the following specimens:

Specimen Type: Tissue

Preferred: Tissue block

Collection Instructions: Submit a formalin-fixed, paraffin-embedded (FFPE) tumor tissue block. Blocks prepared with alternative fixation methods may be acceptable; provide fixation method used.

Acceptable: Slides

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

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

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

Aiding in the diagnosis of mesothelioma by detecting a neoplastic clone associated with deletion involving the CDKN2A gene region at 9p21.

This test includes a charge for application of the first probe set (2 fluorescence in situ hybridization probes) and professional interpretation of results. Additional charges will be incurred for application of 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.

The histologic distinction of malignant mesothelioma from benign mesothelial proliferations can be challenging. Loss of both copies of CDKN2A has been described as a recurrent abnormality in 59% to 80% of pleural malignant mesotheliomas depending on histologic features.(1-3) Homozygous deletion of CDKN2A is less common in peritoneal mesothelioma, reported to occur in 25% to 35% of cases.(2,4,5) The detection of homozygous deletion of CDKN2A by fluorescence in situ hybridization (FISH) has been suggested as a useful adjunct to histologic examination in the differentiation of malignant mesothelioma from other processes.(6,7)

An interpretive report will be provided.

A neoplastic clone is detected when the percent of cells with an abnormality exceeds the normal cutoff. In the proper clinical and histologic context, a positive result may support a diagnosis of mesothelioma. However, homozygous loss of CDKN2A can be identified in many neoplasms. Therefore, clinical and pathologic correlation are required. 

A negative result suggests no deletion of the CDKN2A gene region at 9p21. However, as homozygous deletion is not present in all mesotheliomas, this result does not exclude the diagnosis of malignant mesothelioma. In addition, due to limitations of the technology, fluorescence in situ hybridization cannot detect all CDKN2A deletions.

This test is not approved by the U.S. Food and Drug Administration, 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 fluorescence in situ hybridization (FISH) assays, however nonformalin-fixed samples will not be rejected.

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.

Fluorescence in situ hybridization analysis was performed on 44 formalin-fixed, paraffin-embedded tissue samples including 35 with atypical mesothelioma and 9 with typical mesothelioma. The normal controls were used to generate a normal cutoff for this assay. A deletion of CDKN2A was identified in 7 of the 9 typical mesothelioma (77%) and 2 of 35 atypical mesothelioma (5.7%) specimens.

1. Illel P, Ladanyl M, Rusch V, Zakowski MF: The use of CDKN2A deletion as a diagnostic marker for malignant mesothelioma in body cavity effusions. Cancer. 2003;99:51-56

2. Chiosea C, Krasinkas A, Cagle P, Mitchell KA, Zander DS, Dacic S: Diagnostic importance of 9p21 homozygous deletion in malignant mesotheliomas. Mod Pathol. 2008;21:742-747

3. Hwang H, Pyott S, Rodriguez S, et al: BAP1 immunohistochemistry and p16 FISH in the diagnosis of sarcomatous and despoplastic mesotheliomas. Am J Surg Pathol. 2016;40:714-718

4. Krasinskas A, Bartlett D, Cieply K, Dacic S: CDKN2A and MTAP deletions in peritoneal mesotheliomas are correlated with loss of p16 protein expression and poor survival. Mod Pathol. 2010;23:531-538

5. Singhi A, Krasinskas A, Choudry H, et al: The prognostic significance of BAP1, NF2, and CDKN2A in malignant peritoneal mesothelioma. Mod Pathol. 2016;29:14-24

6. Monaco S, Shuai Y, Bansal M, Krasinskas AM, Dacic S: The diagnostic utility of p16 FISH and GLUT-1 immunohistochemical analysis in mesothelial proliferations. Am J Clin Pathol. 2011;135:619-627

7. Wu D, Hiroshima K, Yusa T, et al: Usefulness of p16/CDKN2A Fluorescence in situ hybridization and BAP1 immunohistochemistry for the diagnosis of biphasic mesothelioma. Ann Diagn Pathol. 2017;26:31-37

The test is performed using a commercially available CDKN2A enumeration probe set. Formalin-fixed, paraffin-embedded tissue samples 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-stained 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 (100 total) with the results expressed as the percent of abnormal nuclei.(Unpublished Mayo method)

Monday through Friday

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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 US Food and Drug Administration.

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)      

88275 - Interphase in situ hybridization, 100 to 300 cells, each probe set (if appropriate)

Sample Reports

Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports

International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports