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Interpretive Handbook

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Test 80258:
Chromosome Analysis, Solid Tumors

Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Most malignant neoplasms are associated with clonal genetic abnormalities and the observation of an abnormal cytogenetic clone is consistent with a neoplasm. In many instances, these abnormalities can be demonstrated by cytogenetic analysis. Some physicians now consider cytogenetic analysis a useful laboratory test to determine the neoplastic potential of solid tumors.

 

For some tumors, cytogenetic analysis can help classify solid tumors. For example, an X;18 translocation has been specifically associated with synovial sarcoma, many alveolar rhabdomyosarcomas have an associated 2;13 translocation, and nearly every myxoid liposarcoma has a 12;16 translocation. A complete summary of the correlation between tumor histology and specific chromosome anomalies is too extensive to summarize here. The reader is referred to the Mitelman Database of Chromosome Aberrations in Cancer (2001). Edited by F Mitelman, B Johansson, F Mertens.Available at http://cgap.nci.nih.gov/Chromosomes/Mitelman

Useful For Suggests clinical disorders or settings where the test may be helpful

Assisting in the classification of malignant tumors associated with chromosomal abnormalities

Interpretation Provides information to assist in interpretation of the test results

The observation of a chromosomally abnormal clone is evidence of a clonal neoplastic process.

 

Certain chromosome abnormalities may also be specifically associated with certain morphologic classifications. In many tumors, the cytogenetic interpretation may be complicated by the observation of numerous complex chromosome anomalies. Nevertheless, the presence of certain chromosome abnormalities within a complex karyotype may still aid in classifying the tumor. However, a normal karyotype does not eliminate the possibility of a neoplastic process. Additionally, FISH testing or other strategies may be more appropriate for certain tumor types.

 

On rare occasions, the presence of an abnormality may be associated with a congenital abnormality that is not related to a malignant neoplastic process. Follow-up with a medical genetics consultation is recommended.

Cautions Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Interfering factors

 

Technical:

-Lack of viable cells

-Bacterial contamination

-Cell death due to failure to transport tissue in an appropriate media

-Excessive transport time

-Exposure of the specimen to temperature extremes (freezing or >30 degrees C)

-Specimen has been stored or treated with formalin or another fixative or is paraffin-embedded

 

Biological:

-Numerous complex anomalies making cytogenetic interpretation difficult beyond establishing the presence of an abnormal clone

-Normal metaphases may be present from tissue within and surrounding the tumor. Normal cells may grow better than cells of the tumor and interfere with the cytogenetic studies

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.

46,XX or 46,XY. No apparent chromosome abnormality.

An interpretive report will be provided.

Clinical References Provides recommendations for further in-depth reading of a clinical nature

Sandberg AA, Turc-Carel C, Gemmell RM: Chromosomes in solid tumors and beyond. Cancer Res 1988;48:1049-1059