A 67-year-old male has shoulder pain and stiffness. What diagnosis can be confirmed with a response to treatment with prednisone?

Polymyalgia rheumatica is an inflammatory condition that typically presents with symptoms such as shoulder pain and stiffness, particularly in individuals over the age of 50. One of the hallmarks of polymyalgia rheumatica is a rapid and significant response to corticosteroids like prednisone. When a patient with polymyalgia rheumatica starts treatment with prednisone, they usually experience a marked improvement in symptoms within days, which can help in confirming the diagnosis.

In contrast, while rheumatoid arthritis can also cause shoulder pain, its response to prednisone is typically less dramatic and may require a broader treatment approach involving disease-modifying antirheumatic drugs. Osteoarthritis, being a degenerative joint condition, would not show significant improvement with corticosteroids, as the inflammation is not the primary issue. A rotator cuff tear primarily involves mechanical problems, and while corticosteroids can help manage inflammation, they do not confirm the diagnosis as clearly as the response seen in polymyalgia rheumatica. Thus, the significant and swift improvement in symptoms following treatment with prednisone is a strong indicator that the diagnosis is polymyalgia rheumatica.