What is the most likely diagnosis for a 65-year-old female with shoulder and pelvic girdle pain, weight loss, and elevated SED rate?

The clinical presentation described—a 65-year-old female with shoulder and pelvic girdle pain, weight loss, and an elevated sedimentation rate (SED rate)—is highly indicative of polymyalgia rheumatica. This condition is common in older adults, particularly those over 50 years of age, and it typically presents with bilateral shoulder and hip pain, morning stiffness, and systemic features such as weight loss or malaise.

The elevated SED rate points toward an inflammatory process, which is characteristic of polymyalgia rheumatica. This condition is often associated with other inflammatory diseases, including giant cell arteritis, and the presence of systemic symptoms along with the specific pain distribution further strengthens the likelihood of this diagnosis.

In contrast, polymyositis typically involves muscle weakness and inflammation of skeletal muscles, which is not a primary feature in this case. Osteoarthritis, while common in older adults, usually presents with joint pain and stiffness but lacks the significant systemic features and elevated inflammatory markers seen here. Fibromyalgia can cause widespread pain and fatigue but is not typically associated with an elevated SED rate or the specific pain patterns of shoulder and pelvic girdle involvement seen in this scenario.

Thus, considering all the factors, polymyalgia rheumatica emerges as the