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Interpretive Handbook

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Test 61239 :
Neuroblastoma, 2p24 (MYCN) Amplification, FISH, Blood or Bone Marrow

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

Neuroblastoma is a small blue cell tumor that occurs typically in early childhood and is usually found in the adrenal glands, but rarely is found in other areas of the body. Approximately 25% of all neuroblastomas have amplification of the MYCN oncogene, located on chromosome 2 at p24. Amplification of the MYCN oncogene correlates with an unfavorable prognosis and aggressive disease.

 

Since metastasis to the bone marrow is common, detection of MYCN amplification in tumor cells present in the bone marrow is important. Prior to ordering this bone marrow test, if possible, testing on the primary tumor sample should be performed. If the primary tumor tests negative for MYCN amplification, bone marrow testing is not indicated. If the primary tumor demonstrates MYCN amplification, identification of MYCN amplification in the bone marrow will confirm the presence of metastatic disease. 

 

In some cases, the diagnostic biopsy specimen from the primary tumor is small and insufficient specimen may be available for ancillary tests such as FISH. In addition, if the primary sample is a bone biopsy, it cannot be used for FISH analysis. In such cases, if metastatic disease involving the bone marrow is identified, FISH testing on the bone marrow can be performed to evaluate for MYCN status in the tumor.

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

Aids in identifying metastatic disease in patients with a neuroblastoma that has been previously determined to be positive for the MYCN oncogene

Interpretation Provides information to assist in interpretation of the test results

A neoplastic clone is detected when the percent of cells with an abnormality exceeds the normal cutoff for any given probe.

 

The presence of a positive clone supports a diagnosis of metastatic disease.

 

The absence of an abnormal clone does not rule out the presence of metastatic disease.

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.

Bone marrow is the preferred sample type. In order to perform testing on peripheral blood, hematopathology review should confirm that tumor cells are present in the blood sample. 

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.

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

1. Van Noesel MM, Versteeg R: Pediatric neuroblastomas: genetic and epigenetic ‘Danse Macabre’. Genes 2004;325:1-15

2. Ambros PF, Ambros IM, Brodeur GM, et al: International consensus for neuroblastoma molecular diagnostics: report from the International Neuroblastoma Risk Group (INRG) Biology Committee. Br J Cancer 2009;5:471-482


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