A 55-year-old executive assistant presents to your office for evaluation of pain in her wrist. She states that the pain has been present intermittently for several months but over the last 2 weeks it has been present daily. She has taken over-the-counter analgesics for the pain which seems to help. She denies fever, chills, or rashes. On physical examination, she has pain and tenderness over the right wrist but not the left. She has a hard dorsolateral nodule on the DIP joint of her right middle finger. The MCP joints are normal. What is your most likely diagnosis?