Q. A 63-year-old male with a 40-pack-year smoking history presents to the clinic with hemoptysis and worsening cough for the past 3 months. He has also experienced weight loss and fatigue. His vital signs are as follows: temperature 37.2°C (99°F), heart rate 90 beats/min, respiratory rate 20 breaths/min, blood pressure 130/85 mm Hg, and oxygen saturation 92% on room air. A chest X-ray reveals a central lung mass. A biopsy of the mass is performed, and the pathology report describes nests of polygonal cells with eosinophilic cytoplasm, intercellular bridges, and keratin pearls. What is the most likely diagnosis for this patient?