Key result
Post-radiation angiosarcoma can histologically mimic radiation dermatitis, but all 10 cases were positive for vascular markers (CD31, CD34, and/or ERG) and MYC.
Observational (n=10)
Post-radiation angiosarcoma can histologically mimic radiation dermatitis, but can be accurately diagnosed using vascular markers and MYC.
IHC for vascular markers and MYC may aid differentiation from radiation dermatitis; leaves open need for validation in larger series.
BACKGROUND: We have encountered cases of post-radiation angiosarcoma (PRAS) histologically mimicking radiation dermatitis. METHODS: Cases of PRAS from institutional/consultation archives from 2006 to 2016 were reviewed. For inclusion, tumors had to have inapparent/subtle tumor at low magnification and scattered individual tumor cells resembling radiation fibroblasts. Prior ancillary studies were reviewed, with additional immunostains performed as needed. RESULTS: 10 cases met criteria. All occurred in women treated for breast cancer (mean age 71 years). All had similar findings: in particular, scattered single atypical cells with pleomorphic nuclei associated with microscopic hemorrhage. They also had narrow, slightly wavy "worm-like" vascular channels lined by atypical endothelial cells that lacked architectural complexity. Four cases showed focal areas of more conventional angiosarcoma. One case was an excision of a large mass that showed the "radiation dermatitis-like" pattern radiating out from the central mass. All were positive for vascular markers (CD31, CD34, and/or ERG) and MYC. MYC amplification was demonstrated by FISH in both cases tested. In 3 of 3 cases with available re-excision specimens, more obvious angiosarcoma was seen. CONCLUSIONS: PRAS can be very subtle and histologically mimic radiation dermatitis. Careful attention to histologic features and ancillary tests allow accurate diagnosis in subtle PRAS.
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Daniels et al. (2017) conducted an observational in Post-radiation angiosarcoma (n=10). Post-radiation angiosarcoma was evaluated on Histologic and immunohistochemical characteristics. Post-radiation angiosarcoma can histologically mimic radiation dermatitis, but all 10 cases were positive for vascular markers (CD31, CD34, and/or ERG) and MYC.
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