Case Report: Metachronous bilateral primary and secondary angiosarcoma of the breast.

Background: Breast angiosarcoma (AS) is an extremely rare and aggressive malignancy with no standardized treatment guidelines. We report an exceptional case of metachronous bilateral primary and secondary AS in a single patient, highlighting the diagnostic and therapeutic challenges posed by this disease. Case presentation: A patient underwent surgical dissection for primary AS of the right breast. Seven months later, a primary AS was identified in the left breast. Four months after that, a secondary angiosarcoma also developed within the previously irradiated left chest wall and axilla. Postoperative pathology confirmed angiosarcoma in all resected specimens. Following multidisciplinary team discussion, the patient received simple mastectomy, adjuvant chemotherapy, and radiotherapy. Despite this multimodal approach, contrast-enhanced CT follow-up revealed rapid disease progression with distant metastases to the lungs, liver, spleen, bilateral adnexa, and bones. The patient ultimately died of respiratory failure secondary to severe pulmonary infection and atelectasis 22 months after the initial diagnosis. Conclusion: This extraordinarily rare case of sequential bilateral primary and secondary breast AS underscores the aggressive biological behavior of this malignancy and the limitations of current therapeutic strategies. It highlights the urgent need for identifying specific diagnostic biomarkers and novel therapeutic targets to enable early detection and improve the dismal prognosis associated with this disease.