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

Secondary angiosarcoma of the breast is a rare and aggressive malignancy, with characteristic <i>MYC</i> 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 <i>MYC</i>-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 <i>MYC</i> amplified, but with distinct <i>MYC</i> amplification patterns. The angiosarcoma demonstrated a 5' <i>MYC</i> only amplification with a breakpoint between the 5' and 3' <i>MYC</i> probes, while the carcinoma harbored a large amplification on chromosome 8q24.21, encompassing both 5' <i>MYC</i> and 3' <i>MYC</i>. 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 <i>MYC</i> gene amplification patterns in the concurrent angiosarcoma and carcinoma reflect the complexity of the <i>MYC</i> gene in the tumorigenesis of different types of malignancies and may explain the different levels of MYC protein expression on immunohistochemistry.