A 60-year-old man presents to the clinic with generalized fatigue for 4 months. He says he has been feeling depressed and weak lately and his mood has had a negative impact on his relationship with his wife. He also reports recent acne flares, which he says he has not struggled with since college. He is a 30-pack per year smoker and has hypertension, previously well controlled on his current regimen. Vitals taken today shows a BP of 165/95 mmHg. A physical exam reveals an adipose deposit on the dorsal upper thorax and abdominal striae. A chest X-ray reveals a hilar lung mass.
Which of the following tumors most commonly produces the paraneoplastic syndrome seen in this patient?