A 75-year-old man is brought to the hospital with complaints of increased fatigue, weight loss, shortness of breath, and hemoptysis for several months. He immigrated from an East Asian country last year. Physical examination reveals a palpable mass in the right upper quadrant. α-Fetoprotein level is 1432 ng/mL. X-ray of the chest reveals a 10-cm lesion in the right lower lobe of the lung. Which of the following additional findings is most likely in this patient?