A 64-year-old man comes to the physician for a 2-month history of headache and arm weakness. He has lost 10 pounds during this time. Physical examination shows weakness of the proximal upper and lower extremities. MRI of the brain shows a single ring-enhancing lesion. Biopsy of the lesion is shown. Which of the following additional findings is most likely to be seen in this patient?
Gottron papules
Increased urinary 5-HIAA
Osteoblastic metastases
Potassium wasting
Weakness with repetitive nerve stimulation
