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Questions

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A78-yeаr-оld wоmаn repоrts а one-year history of pain in both hands. The pain is constant, associated with stiffness, and especially severe at the distal interphalangeal (DIP) joints. Her second DIP on the left, which is erythematous, is bothering her most. She also notes that her DIPs are becoming "deformed", as she recalls her mother's had been in the older age. She reports no clear worsening of symptoms in the morning or with activity. Physical examination reveals deformities and lateral bony prominences at several DIP and proximal interphalangeal joints in both hands, and her second DIP on the left is also tender and erythematous. Her metacarpophalangeal joints are normal. No other joint pain or discomfort is evident, except for crepitus in both knees. Her examinations is normal, as is the rest of her physical examination. What is the most likely cause of this patient's hand discomfort?