Abstract
Superior vena cava syndrome (SVCS) is an oncological emergency. Lung cancer is the most causative malignancy. In con-trast, breast cancer rarely causes SVCS. We report a case in which SVCS was caused by mediastinal lymph node metastasis
of breast cancer. The patient was a 60-year-old woman who had undergone breast-conserving therapy at another hospital 13
years previously. Her breast cancer was early stage (T1a(5mm)N0M0; Stage IA), and Luminal type (HER2 negative). She had
received adjuvant hormone therapy, but dropped out of treatment two years and six months later. Recently, she had developed
cough and face edema, and her extrajugular vein was swollen. CT revealed swollen mediastinal and supraclavicular lymph
nodes, lung nodules, pericardial effusion, right pleural fluid, and stenosis of the superior vena cava (SVC). She was diagnosed
with recurrent breast cancer with SVCS due to mediastinal LN swelling. A core needle biopsy of a supraclavicular lymph node
revealed metastasis; the diagnosis was luminal HER2 positive breast cancer. We initiated treatment with radiotherapy for the
mediastinal lymph nodes, and then started hormone therapy and anti-HER2 therapy. These therapies provided relief from her
symptoms. She is currently alive and continuing hormone therapy and anti-HER2 therapy. In cases of SVCS due to malig-nancy, the biopsy findings should be taken into account when possible. An accurate diagnosis is extremely important for the
suitable treatment of SVCS, especially in cases caused by malignancy.
