This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory System, Subject name: Radiology
[{'content': "A 60-year-old chronic smoker presents with weight loss, cough and hemoptysis. A chest radiograph was obtained and revealed this appearance. The patient developed over the next few days a gradually progressive left upper limb pain, paraesthesia and weakness. He also developed left sided Horner's syndrome. Most likely diagnosis is: \nSelect and explain. \nA. Fungal ball, B. Pulmonary hydatid cyst, C. Pancoast tumour, D. Hamartoma", 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C Pancoast tumourYou can see a left apical mass (radio opacity) causing gross destruction of overlying ribs and soft tissues - suggests Pancoast tumourQ. Most commonly - Squamous cell carcinomaQ. MRI is IOCQ.', 'role': 'assistant'}]