Radiation-associated angiosarcoma in the setting of breast cancer mimicking radiation dermatitis: A diagnostic pitfall

Abstract

Background

We have encountered cases of postradiation angiosarcoma (PRAS) histologically mimicking radiation dermatitis.

Methods

Cases of PRAS from institutional/consultation archives from 2006–2016 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

Ten 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 vascular 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 3/3 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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