PLE-7937

A 56-year-old male patient presents to your clinic due to weight loss and the presence of a palpable, nontender, fixed lymph node located at the posterior triangle of the neck (level V). He has an unremarkable history, other than smoking for approximately 30 years. Biopsy reveals squamous cell carcinoma. You suspect that this malignancy most likely originated from what region of the head and neck?