Concurrent MYC-Amplified Secondary Angiosarcoma and Recurrent Carcinoma in the Breast: A Rare Presentation With Unique Clinical Features and Distinct MYC Amplification Patterns.

Secondary angiosarcoma of the breast is a rare and aggressive malignancy, with characteristic MYC amplification. It typically arises in the field of prior radiation for breast cancer treatment, or rarely, in patients with a history of radical mastectomy with axillary lymph node dissection. Concurrent angiosarcoma and carcinoma in the same breast is exceedingly rare. In this report, we describe a rare occurrence of concurrent MYC-amplified angiosarcoma in the breast skin and recurrent carcinoma in the breast parenchyma in a patient without any history of breast radiation or axillary lymph node dissection. In addition, both angiosarcoma and carcinoma were MYC amplified, but with distinct MYC amplification patterns. The angiosarcoma demonstrated a 5' MYC only amplification with a breakpoint between the 5' and 3' MYC probes, while the carcinoma harbored a large amplification on chromosome 8q24.21, encompassing both 5' MYC and 3' MYC. This case report highlights the occurrence of secondary angiosarcoma arising in a patient without a history of prior radiotherapy or an axillary dissection, as well as the rare concurrence of angiosarcoma and carcinoma in the same breast. More intriguingly, the distinct MYC gene amplification patterns in the concurrent angiosarcoma and carcinoma reflect the complexity of the MYC gene in the tumorigenesis of different types of malignancies and may explain the different levels of MYC protein expression on immunohistochemistry.