A 45-year-old woman has noted a lump on her left shoulder that has enlarged over the past 4 months. On physical examination there is a palpable non-tender supraclavicular lymph node. A biopsy of the node is performed and on microscopic examination there is a metastatic neoplasm. Which of the following is the most likely primary for this neoplasm? A: Cerebral glioma B: Fibroadenoma of the breast C: Adenocarcinoma of the stomach D: Liposarcoma of the retroperitoneum E: Laryngeal papilloma