Review Question - QID 213365

A 62-year-old man presents to the clinic for right arm pain for the past 3 months. The pain is described as dull, 7/10 in severity, and concentrated along his right shoulder and the 4th and 5th digits. He denies fever, chest pain, palpitations, dyspnea, urinary symptoms, or abdominal pain, but endorses a recent 10 lb weight loss. The patient also reports a fall on his outstretched arms 2 months ago. His past medical history is significant for diabetes and hypertension. A physical examination demonstrates decreased pinprick sensation in the right 4th and 5th digits, hypothenar muscle atrophy, and eye findings shown in Figure A. What is the most likely explanation for this patient’s symptoms?