Angiosarcoma, MYC (8q24) Amplification, FISH, Tissue
Identifying MYC amplification to aid in the differentiation of cutaneous angiosarcomas from atypical vascular lesions after radiotherapy
Aids in the diagnosis of primary cutaneous angiosarcoma
Clinical Information Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test
Postradiation cutaneous angiosarcoma is a malignancy associated with very poor outcome and is consequently treated aggressively. Conversely, atypical vascular lesions are also associated with radiation therapy, but are considered to be benign and do not require aggressive management. Therefore, the differentiation of these neoplasms is of considerable clinical importance. Postradiation cutaneous angiosarcomas are characterized by high-level amplification of MYC, whereas reactive and benign vascular lesions do not show amplification of MYC. Similar diagnostic difficulties arise in the setting of primary cutaneous vascular lesions. A subset of primary cutaneous angiosarcomas also shows high-level MYC amplification, which can be useful in the differentiation from benign primary cutaneous vascular lesions.
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.
An interpretive report is provided.
The MYC locus is reported as amplified when the MYC:D8Z2 ratio of 2.0 or greater and demonstrates 6 or more copies of the MYC locus.
A lesion with a MYC:D8Z2 ratio <2.0 or showing a ratio of 2.0 or greater with less than 6 copies of MYC is considered to lack amplification of the MYC locus.
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.
This test is only for the distinction of cutaneous angiosarcomas from benign cutaneous vascular lesions, particularly in the postradiation setting.
Fixatives other than formalin (eg, Prefer, Bouin) 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.
The probe set was independently validated in a blinded study on 23 paraffin-embedded primary and postradiation angiosarcoma tissue samples and 25 nonneoplastic control specimens. MYC amplification was detected in 4 (17.4%) of the angiosarcomas and the incidence is consistent with published reports.
Clinical Reference Provides recommendations for further in-depth reading of a clinical nature
1. Mentzel T, Schildhaus H, Palmedo G, et al: Postradiation cutaneous angiosarcoma after treatment of breast carcinoma is characterized by MYC amplification in contrast to atypical vascular lesions after radiotherapy and control cases: clinicopathological, immunohistochemical and molecular analysis of 66 cases. Mod Pathol 2012;25:75-85
2. Manner J, Radlwimmer B, Hohenberger P, et al: MYC high level gene amplification is a distinctive feature of angiosarcomas after irradiation or chronic lymphedema. Am J Pathol 2010;176(1):34-39