Unusual presentation of superior vena cava syndrome secondary to breast cancer.

We present a rare case of a woman in her 50s with recurrent, metastatic breast cancer who developed superior vena cava (SVC) syndrome, followed by in-stent thrombosis. SVC syndrome is an uncommon presentation in breast cancer, typically caused by malignancies like lung cancer or lymphoma. Initial imaging revealed a mediastinal mass causing vascular invasion of the SVC. Despite stent placement and palliative treatments, she experienced recurrent symptoms due to complete occlusion of the stents. Further interventions included angioplasty and stent realignment, followed by anticoagulation. This case highlights the complexities of managing SVC syndrome and emphasises the potential for recurrent thrombosis.