MYC gene amplification is a rare event in atypical fibroxanthoma and pleomorphic dermal sarcoma
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Timo Gaiser1,*, Daniela Hirsch1,*, Azadeh Orouji2,*, Marisa Bach2, Peter Kind4, Doris Helbig5, Alexander Quaas6, Jochen Utikal2,3, Alexander Marx1 and Maria Rita Gaiser2,3
1Institute of Pathology, University Medical Center Mannheim, Ruprecht-Karl University of Heidelberg, Mannheim, Germany
2Department of Dermatology, Venereology and Allergology, University Medical Center Mannheim, Ruprecht-Karl University of Heidelberg, Mannheim, Germany
3Skin Cancer Unit, German Cancer Research Center (DKFZ), Heidelberg, Germany
4Dermatohistological Laboratory Professor Kind, Offenbach, Germany
5Department of Dermatology, University Hospital Cologne, Cologne, Germany
6Institute of Pathology, University Hospital Cologne, Cologne, Germany
*These authors contributed equally to this work
Maria Rita Gaiser, email: firstname.lastname@example.org
Keywords: AFX; amplification; FISH; MYC; PDS
Received: October 11, 2017 Accepted: March 17, 2018 Published: April 20, 2018
Atypical fibroxanthoma (AFX) and pleomorphic dermal sarcoma (PDS) are rare malignancies typically occurring in elderly patients and predominantly located in skin regions exposed to UV-light. Thus, a role of UV-radiation-induced damage for AFX and PDS tumorigenesis has been postulated.
MYC gene amplification has been demonstrated as a distinctive feature of radiation-induced angiosarcoma. In order to investigate whether chronic exposure to UV-light might also lead to MYC copy number changes, 51 AFX and 24 PDS samples were retrospectively analyzed for MYC amplification by fluorescence in situ hybridization using a MYC and a CEP8 gene probe. Of the 44 analyzable AFX samples, one case showed MYC amplification (defined as a MYC/CEP8 ratio ≥2.0), whereas 13 cases demonstrated low level copy number gains (defined as MYC/CEP8 ratio ≥ 1.2−< 2.0). MYC amplification was seen in an AFX sample of extraordinary tumor thickness of 17.5 mm (vs. median 3.25 mm for all samples). Of the 24 PDS cases, five specimen demonstrated MYC low level copy number gains. Immunohistochemically, neither the AFX nor the PDS cases showed MYC protein expression.
In summary, these findings rule out that MYC amplification is a major genetic driver in the process of AFX or PDS tumorigenesis. However, MYC amplification may occur as a late event during AFX development and hence might only be detectable in advanced, thick lesions.
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