C51-21 Diagnostic Delay and Rapid Progression of Primary Breast Angiosarcoma in a Young Woman

Abstract Angiosarcoma accounts for less than 0.05 percent of all breast malignancies. It is characterized by aggressive local growth, frequent hemorrhage, and early hematogenous dissemination. A 20-year-old female was evaluated at an urgent care for a 5 cm left breast mass 6 months prior to admission. She since underwent three biopsies and partial excisions; none of which were diagnostic. On initial presentation the patient was lightheaded with active bleeding from the left breast mass. Her hemoglobin was 6.5 g/dL and she received one unit of packed red blood cells (PRBC). A CT chest with contrast revealed a fungating left breast mass abutting the pectoralis muscle. A 6.8 cm hypoattenuating hepatic lesion was also noted. The patient continued to have bleeding, and three additional transfusions were required. Interventional radiology performed embolization of the branches of the left internal mammary artery. However, the patient required yet another PRBC transfusion shortly thereafter. Surgery performed a partial mastectomy with cautery and tying of bleeding vessels. The two units PRBC and one unit fresh frozen plasma (FFP) were administered intraoperatively. The patient was discharged with plan to follow up on the pathology report of the excised breast tissue. Four months later, the patient returned to the emergency department with worsened enlargement of the left breast mass, new onset right upper quadrant pain, nausea, vomiting, early satiety, abdominal distention, and back pain. Imaging demonstrated: Massive right hepatic lobe mass (24 cm) with heterogeneous arterial enhancement, concerning for metastasis over hemangioma. Residual and new left breast soft tissue lesions. Enlarging lung nodules (e.g., right middle lobe from prior 4 mm to 7 mm). Progression of T7 vertebral lesion consistent with osseous metastasis. Given the extent of disease and vascularity, surgical excision was not feasible. The patient deferred inpatient chemotherapy and was discharged with local oncology follow-up. She presented the next month with pulsatile bright red bleeding from her exophytic breast mass. She eventually agreed to receive inpatient chemotherapy, and a venous access device was implanted to continue chemotherapy as outpatient. This case exemplifies challenges in the management of angiosarcoma including diagnostic delay, pathologic uncertainty, rapid metastatic spread, and multidisciplinary coordination. Breast angiosarcoma is a rare yet highly aggressive malignancy, this case underscores the pitfalls in diagnosis and complexity of managing recurrent bleeding and systemic spread. Clinicians encountering vascular breast lesions should maintain a high index of suspicion, expedite imaging and biopsy, and ensure rapid referral to specialists. This abstract is funded by: None